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<pubnumber>420P07003</pubnumber>

<title>SmartWay Fuel Efficiency Test Protocol for Medium and Heavy Duty Vehicles: Working Draft</title>

<pages>76</pages>

<pubyear>2007</pubyear>

<provider>NEPIS</provider>

<access>online</access>

<origin>PDF</origin>

<author></author>

<publisher></publisher>

<subject></subject>

<abstract></abstract>

<operator>mja</operator>

<scandate>12/16/08</scandate>

<type>single page tiff</type>

<keyword></keyword>



   Smart Way Fuel Efficiency Test Protocol

   for Medium and Heavy Duty Vehicles

   Working Draft

United States

Environmental Protection

Agency

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                Smart Way Fuel Efficiency Test Protocol

                for Medium  and Heavy Duty Vehicles

                                    Working Draft

                              Transportation and Regional Programs Division

                                 Office of Transportation and Air Quality

                                 U.S. Environmental Protection Agency

v>EPA

                   NOTICE



                   This technical report does not necessarily represent final EPA decisions or

                   positions. It is intended to present technical analysis of issues using data

                   that are currently available.  The purpose in the release of such reports is to

                   facilitate the exchange of technical information and to inform the public of

                   technical developments.

United States                                          EPA420-P-07-003

Environmental Protection                                   .,    ,  „„.,

Agency                                              November 2007

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Table of Contents

1. Foreword	5

2. Purpose and Scope	6

3. Overview of Test Methods	9

   3.1 Track Test	 10

   3.2 Chassis Dynamometer Test	12

4. Vehicle Selection	13

5. Test Fuel	14

6. Test Track Specifications and Requirements	15

   6.1 Track Specifications	 15

   6.2 Track Requirements	16

   6.3 Track Environmental Requirements	17

7. Chassis Dynamometer Specifications and Requirements	18

   7.1 Chassis Dynamometer Specifications	18

   7.2 Chassis Dynamometer Requirements	 19

   7.3 Chassis Dynamometer Environmental Requirements	20

8. Test Equipment Specifications	20

   8.1 Laboratory Emissions Monitoring System	20

   8.2 Portable Emissions Monitoring Measurement System	21

   8.3  Gravimetric Fuel Consumption Measurement System	21

9. Drive Cycle Selection	22

   9.1 Drive Cycle Selection Criteria	22

   9.2 Highway Line Haul	23

   9.3 Regional Haul	25

   9.4 Local Pick Up and Delivery	25

   9.5 Neighborhood Refuse Truck	27

   9.6 Utility Service Truck	28

   9.7 Transit Bus	29

   9.8 Intermodal Drayage Truck	32

10. Accessory Load	33

   10.1 Heating and Ventilation, Defrosting	33

   10.2 Air Conditioning	34

   10.3 Power Take-off (PTO) or Other Vocational/Service Work Load	34

   10.4 Lamps and Lights	34

   10.5 Miscellaneous	34

   10.6 Drive Cycle Load Requirements	34

11. Vehicle Payload and Test Weight	35

   11.1 Test Equivalent Weight	37

   11.2 Test Fuel Weight and Volume	37

12. Test Set-Up Procedure	38

   12.1 Test Payload	38

   12.2 Tire Pressure	38

   12.3 Mechanical  Preparation of Test Vehicle	38

   12.4 Vehicle Preconditioning	39

   12.5 Hybrid Vehicles - Additional Vehicle Conditioning	40

   12.6 Hybrid Vehicles - Procedures for Determining State of Charge (SOC) and Net Energy

   Change (NEC)	41

   12.7 Fuel Analysis	43

13. Test Procedure	43

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   13.1 General Requirements	43

Driver Conduct	43

   13.2 Test Procedure for Test Track	46

   13.3 Test Procedure for Chassis Dynamometer	47

   13.4 Coastdown Test Procedure to Calculate Road Load	49

14 Required Number of Test Runs	50

   14.1 General Requirements	50

   14.2 Number of Test Runs for Test Track Test	51

   14.3 Number of Test Runs for Chassis Dynamometer Test	52

15 Fuel efficiency Calculation	54

16 Reporting and Documentation	55

   16.1 Reports	55

   16.2 Data and Metrics	56

   16.3 Quality Assurance and Control	56

   16.4 Assessment	57

17 Appendices	58

       17.1 Appendix A     	59

       17.2 - 17.8 Appendices B - H	61

       17.9  Appendix I     	62

       17.11 Appendix K    	71

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List of Figures and Tables

[Reserved]

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1.  Foreword

Advancements in heavy duty vehicle technology offer the potential for significant

improvements in important vehicle attributes, including efficiency and emissions

performance. In 2004, the U.S. Environmental Protection Agency (EPA) initiated the

SmartWaySM Transport Partnership to accelerate the deployment of fuel-efficient, clean

technologies for heavy duty vehicles.  SmartWay Transport is an innovative collaboration

between EPA and the transportation industry to improve energy efficiency, reduce

greenhouse gas and air pollutant emissions, and improve energy security. Through

SmartWay, EPA works in collaboration with industry and other stakeholders to provide

incentives for adopting  cleaner, more fuel efficient transportation technologies to benefit

the environment.



An important aspect of the SmartWay Transport Partnership  is to determine through

testing and  analysis the environmental benefits of heavy truck  technologies, and to

provide this information to  SmartWay partners and to the general public.  SmartWay is

developing this fuel efficiency test protocol for heavy  duty  trucks to better quantify the

benefits of various heavy  vehicle designs  and  technologies.  EPA currently  offers a

"SmartWay  designation" for over-the-road  tractor-trailer combination trucks.   It is a

design-based specification,  developed on  this  basis of  test results  for  individual

components (tires, wheels, aerodynamic equipment, auxiliary power units, engines) that

have been demonstrated to improve fuel efficiency and reduce  emissions.  EPA,  its

SmartWay partners, and others would like to expand the SmartWay designation for heavy

duty vehicles by moving toward a performance-based specification.  A performance-

based specification would be technology-neutral, and able to quantify  a broad  range of

heavy vehicle configurations and applications, and to  measure technical innovations as

they emerge.



Moving toward a performance-based  specification requires  using a test  to  measure

vehicle fuel efficiency.  Component testing alone is not sufficient, since the fuel-saving

impacts can  vary  widely based upon  vehicle application.  However, a standardized,

objective,  stand-alone fuel efficiency test to measure the fuel efficiency of a heavy duty

on-highway vehicle does  not  currently  exist.   This absence presents a  significant

challenge to SmartWay, the Agency and industry. Without a test method, it is difficult to

develop a common understanding of how to assess and compare the fuel efficiency of

heavy duty vehicles, including vehicles with  hybrid powertrain,  varying aerodynamic

configurations,  and other advanced vehicle designs. EPA recognizes that there is a wide

variety of truck configurations for each base model and that it may not be possible to test

every configuration to  see  if it meets the SmartWay performance specification.  As a

result, EPA is looking at methods to extend fuel efficiency testing to cover additional

truck configurations. Tools such as the consistent use of vehicle modeling, tire rolling

resistance  testing,  and aerodynamic  evaluations could  potentially  broaden a fuel

efficiency testing program.



This test procedure applies to medium and heavy duty vehicles as per 40 CFR §86.082-2.

This means any motor vehicle rated at more than 8,500 pounds GVWR or that has a

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vehicle curb weight of more than 6,000 pounds or that has a basic vehicle frontal area in

excess of 45 square feet. Vehicles in this group are typically tractor-trailer combination

trucks, single unit commercial trucks, heavy duty vocational trucks, and buses used in

inter-city transit applications.  EPA does have an optional chassis certification procedure

for heavy duty diesel vehicles under 14,000 pounds GVWR, used in federal regulatory

programs (§86.1863-07).  This test procedure incorporates many aspects of the optional

chassis test procedure, but does not replace it for the purposes of certifying to the

standards specified in §86.1816-08.



Heavy duty vehicle manufacturers are required to use engines that are certified to U.S.

Environmental Protection Agency (EPA) emission standards (per 40 CFR Part 86,

Subpart N) but those test procedures measure engine (rather than vehicle) brake specific

fuel consumption performance and focus on emissions rather than fuel efficiency.  The

existing tests do not quantify fuel efficiency  benefits from the unique features of a hybrid

drive train (regenerative braking, reductions in engine transient operation, smaller

engines) or fuel efficient vehicle components (single wide base tires, aerodynamic

equipment.)  This test procedure will serve as an objective means to evaluate these and

other emerging fuel-saving technologies, and to standardize the measurement of heavy

duty vehicle fuel efficiency.



This test procedure is intended to be used on a voluntary basis to determine whether

vehicle configurations meet or exceed SmartWay performance specifications. Other

users may also wish to apply it for their own purposes. For example, the test procedure

can be used to calibrate and verify vehicle software models, allowing for greater

consistency among models.



This protocol references various SAE standards, federal regulations, and other source

documents.  Those documents should be acquired in order to conduct tests in accordance

with this  protocol.



This "working draft" document contains a number of "reserved" sections.  It is presented

for stakeholder review in order to assist EPA in resolving certain outstanding technical

issues contained in the "reserved" sections and elsewhere. We encourage stakeholders

and other interested parties to comment on this document and provide EPA with advice

on the technical issues.

2.  Purpose and Scope

The purpose of this document is to provide a standardized, objective, consistent test

procedure to measure the  fuel consumption of heavy duty vehicles used in on-road

operation. As mentioned in the Foreword,  this test procedure is being developed to

support the aims of the EPA SmartWay Transport Partnership, and to fill a real need in

the trucking industry. SmartWay Transport is an innovative collaboration between EPA

and the transportation industry to improve energy efficiency, reduce greenhouse gas and

air  pollutant emissions,  and improve  energy security.  An important  aspect of the

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Partnership is to determine through testing and analysis the environmental benefits of

heavy truck technologies, and to provide this information to SmartWay partners and to

the general public.  SmartWay is developing this fuel efficiency test procedure for heavy

duty trucks  to  better quantify the  benefits  of  various  heavy  vehicle  designs  and

technologies.  This  test  procedure  provides test  requirements  and  methods  that are

appropriate for a number of different truck types, based on the specific application or

service category of the heavy duty vehicle.



This test protocol fills a real need,  since there is no widely-accepted, standardized test

procedure to measure the real-world fuel consumption performance  of a heavy duty

vehicle.  SAE J1321 (or alternatively, SAE J1526) has been used to partially fill  this gap,

but these  test  methods  do  not  measure  absolute  vehicle fuel efficiency, but  an

improvement in fuel efficiency from a baseline condition.1  This is not useful as a stand-

alone metric, since  the baseline  condition is not standardized.  More  importantly, drive

cycles are not standardized.



The test protocol described in this document measures fuel consumption directly, and the

desired fuel consumption metric for this test procedure is fuel consumed per unit  of work

performed (e.g., gallons per mile or per ton-mile; for vocational trucks with power take-

off, gallons per hour).  Alternatively, the metric can be work performed per volume of

fuel consumed (e.g., miles or ton-miles per gallon).  A fuel consumption rather than a

percent improvement metric allows for a stand-alone efficiency measure for any given

truck model.  It also provides a consistent, objective, standardized means to compare the

fuel efficiency of two or more tested trucks.



The test procedure described here is  intended to provide the federal government, states,

industry, academia,  and others with an objective testing method to assess the fuel

efficiency performance of heavy  duty vehicles for a variety of purposes. These purposes

may include quantifying and benchmarking in-use fuel consumption; verifying fuel

savings for federal and state incentives; demonstrating environmental performance to

achieve targets for innovative industry, federal and state programs; and, providing

quantification of carbon dioxide reductions.



A major challenge to our collective understanding of heavy truck fuel efficiency is the

lack of standardized, comparative test data.  This test procedure could be used to test

several trucks at the same facility, under  stable test conditions. The results could be used

to establish "environmental reference" vehicles, against which other heavy duty vehicles

could be tested in the future. Using this test procedure to establish environmental

reference trucks can provide a flexible, cost-effective means to build comparable data

sets and improve our ability to analyze and understand heavy truck performance.



This test procedure establishes uniform test conditions for the most  common  types of

heavy duty highway vehicles and applications.  Uniform test conditions include:

    •  vehicle selection

    •  fuel specification

    •  test facilities and environment

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    •   test equipment

    •   drive cycle

    •   accessory load

    •   test set-up procedures



The specificity makes the test procedure effective for benchmarking a specific vehicle

design, and for comparing fuel-saving vehicle designs within a given application.

The protocol establishes different test requirements and methods depending on vehicle

type,  based on  a  classification according to service  category,  or vehicle application.

These categories  cover  many common types of heavy duty vehicle uses, including

tractor-trailer combination line haul and regional  haul trucks, local pick up and delivery

vehicles,  transit  buses,  neighborhood refuse haulers,  utility trucks,  and  intermodal

drayage trucks.  This document can be updated at appropriate times to supplement the

initial heavy duty vehicle categories with additional heavy duty vehicle drive cycles.



The test procedure is designed to be technology-neutral and applicable to a conventional

internal combustion engine or a hybrid  powertrain configuration.2  However, this test

procedure does not provide test or data analysis  methods to adequately account for the

energy usage of a charge-depleting ("plug-in") hybrid vehicle.  This protocol should only

be used to test such vehicles in the charge-sustaining mode.

This test procedure protocol does not provide any test methods or data analysis

methods for non-liquid fuels.



This test procedure incorporates references to a number of different resources, including

various SAE practices, federal regulations, and other source materials.  These materials

are referenced for the convenience of the user. It is advisable to acquire the referenced

materials prior to conducting this test, to facilitate implementation of this protocol.



The vehicles covered by this  test procedure are  heavy duty vehicles, as defined by  40

CFR  §86.082-2  and §86.090-2, which consist of any motor vehicle  rated at more than

8,500 pounds GVWR or that has a vehicle curb weight of more than 6,000 pounds or that

has a basic vehicle frontal area in excess of 45  square feet.  Vehicles in this group are

typically tractor-trailer combination trucks,  commercial  straight trucks,  heavy  duty

vocational trucks, and buses used in municipal transit applications.



The initial  focus in this document will be on heavy duty  vehicle applications with the

greatest near-term potential to benefit from fuel-saving technology:3



    •   Highway line haul  combination tractor-trailer

    •   Regional haul combination tractor-trailer

    •   Local pick up and delivery truck (e.g., parcel, beverage)

    •   Neighborhood refuse truck

    •   Utility service truck

    •   Transit bus

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   •   Intermodal drayage truck



The heavy duty vehicle categories listed in this test protocol overlap but don't fall

perfectly within existing intended service categories for heavy duty diesel engines, as

defined in the federal emissions certification program.  According to 40 CFR §86.090-2,

the intended service category for a heavy duty engine is the primary service application

group for which a heavy duty diesel engine is designed and marketed, as determined by

the manufacturer. The determination is based on factors such as vehicle GVWR, vehicle

usage and operating patterns, vehicle design, engine horsepower, and engine design and

operating characteristics.

3.  Overview of Test Methods

The fuel consumption  of the test vehicle is measured by operating the vehicle on either a

test track or on a chassis dynamometer over a specified drive cycle and measuring the

fuel consumption.  Fuel consumption can be calculated on the basis of a mass balance of

carbon-bearing emission gases (CC>2, CO, CH/t, other hydrocarbons) as described in 40

CFR Part 86  and SAE test method  J1094a4 or on  the  basis of  a gravimetric fuel

measurement system using portable fuel tanks as described in SAE test method J1321, in

which the mass of fuel consumed is converted to volume using measurements of fuel

density.



Track tests can be conducted using either the  gravimetric  method or the carbon mass-

balance method using a portable emissions monitoring system, or PEMS.



Chassis dynamometer tests  are conducted using the  carbon-balance method  and

laboratory gas  analysis instrumentation (preferable) or the gravimetric method.



This test  procedure does not address the  comparability of track testing to chassis

dynamometer  testing.   More data is needed  to  develop robust  correlation  factors.

Preliminary testing indicates a dynamometer-to-track difference in  the range of 4% to

10%.   This difference may be  explained by  tire/surface interactions  and test-to-test

variability.  However,  both  track  and  chassis   dynamometer   tests  demonstrated

directionally consistent and statistically equivalent differences to changes in drive cycle

for various  vehicles.5  EPA  encourages comments  regarding possible methods  for

correlating results of  track tests  and  dynamometer tests.  Comments received to date

suggest a preference for laboratory dynamometer testing, but EPA would  like to retain a

standardized track test method in this document, if only to provide a means to relate the

results of dynamometer testing to more realistic  on-road performance.

Figure xx shows the steps in the overall conduct of the testing, for whichever path has

been chosen.



The following overview is designed to help the user determine which test method is more

appropriate for their needs.

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3.1 Track Test

A track test is a vehicle test conducted on an outside test track. Test tracks may be found

at vehicle  proving  grounds or other facilities specifically designed for vehicle or tire

performance  testing.  Although any type of heavy duty vehicle can be tested on a test

track, this option may be more suited to typical over-the-road heavy duty vehicles, like

combination tractor-trailers.6



Because the test involves the vehicle being operated on a road surface in a manner similar

to that of on-road driving, rolling resistance, aerodynamic drag, and inertial road load

power requirements are incorporated in the test measurement,  and do not have to be

determined beforehand with a coastdown test and calculations.  Although the result of a

track test reflects real-world vehicle performance better than a chassis dynamometer test,

by directly evaluating the impacts of road  effects such  as aerodynamic drag of tractors

and trailers and rolling resistance effects of tires, variability of ambient conditions may

result in greater variability  of test results.7   This  protocol  includes  specification  of

ambient conditions as well as specifications for measurement of fuel consumption.



Additionally, a coastdown test should be performed to document the road load force the

vehicle experiences during the track test. See section 13.4 for details.

                                                                                10

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Figure 1.  Protocol Sequence

                 §3



       Choose Test Methodology

                 I

                 §4



         Select Test Vehicles

              §9 and §10



    Select appropriate drive cycle and



    accessory load for testing

              §11 and §12

         Precondition vehicles

                 I

             §6, §7, and §8





     Follow Dyno, Test Track, and



   PEMS requirements, as applicable

                 §12



   If hybrid, determine SOC and NEC

                 I

             §13 and §14



        Determine Number and

     Sequence of Test Repetitions

                 §12



     Conduct warm up and test runs.



     Include all equipment and PEMS



     calibration and fuel analysis

                 I

                §14 and §15



             Analyze Data

                                                                         11

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Detailed  methodology for the  gravimetric method  of measuring  fuel consumption  is

described in §§5.7.1 and 5.7.3 of the joint TMC/SAE Fuel Consumption Test Procedure -

Type II, Surface Vehicle Recommended Practice J1321 (SAE J1321). Fuel consumption

is measured by weighing the fuel consumed using a portable fuel tank. In this method, a

portable fuel tank is weighed empty, filled with fuel, weighed again, and then mounted

on the test vehicle. The test vehicle's fuel  line is  connected to the  portable tank the

moment the test begins, and disconnected at the conclusion of the drive cycle, after which

the portable tank is removed and reweighed.  The fuel consumed during  the  test  is

calculated using the density of the fuel and the difference in the weight of the portable

fuel tank before and after the test, to yield the volume (gallons) of fuel used.



The carbon balance method of measuring fuel consumption on the basis of SAE test

method 1094a (and in accordance with  CFR 40  Part  86) uses  an  onboard  portable

emissions monitoring  system  (PEMS) to  measure the mass of carbon emitted  in the

exhaust, as well as the exhaust flow.  The PEMS records this information via an onboard

data acquisitions system.



Details for PEMS requirements can be found in 40 CFR  Part 1065, Subpart J. Because

PEMS became commercially available only  recently,  the portable  tank gravimetric

method has been more extensively used for track tests in the past.



3.2 Chassis Dynamometer Test

A  chassis  dynamometer  test  is a test conducted indoors  on a  hydrokinetic  chassis

dynamometer.  The chassis dynamometer option in this test procedure incorporates many

of the methods and requirements established in the federal light duty vehicle and 'light'

heavy duty vehicle emissions certification  chassis test procedure. Although most heavy

duty vehicles can  be tested on a chassis dynamometer, this option may be more suitable

for single unit truck and truck body heavy duty vehicles.8



Chassis dynamometers may be found at vehicle test laboratories; typically, facilities used

for emissions and vehicle fuel efficiency  testing.  Because the test is conducted on a

chassis dynamometer,  rolling resistance, aerodynamic drag and inertial road load power

requirements must be determined ahead of time, with coastdown tests and calculations to

determine the proper horsepower absorption setting for the chassis dynamometer.  Details

for conducting coastdown  tests are found in the section of this test procedure covering the

chassis dynamometer test method.



When using the chassis dynamometer option in this test procedure, fuel consumption can

be measured using the carbon balance  method, in which fuel consumption  can be

calculated on the  basis of a mass balance of carbon-bearing emission gases  (CO2, CO,

CH4, other hydrocarbons) as described in SAE  test method J1094a.  In this method,

vehicle emissions are  collected and analyzed using  laboratory gas analyzer equipment.

The laboratory equipment  measures and records the concentration of  carbon-based

compounds emitted in the exhaust as well as the exhaust flow. The concentrations and

densities of the carbon-based compounds, and exhaust flow values,  are used to calculate

the mass of fuel consumed.  The volume of fuel consumed is determined by the mass of

                                                                             12

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fuel consumed and the density of the fuel. This method of measuring heavy duty vehicle

fuel consumption on a chassis dynamometer is substantially similar to the method used to

measure fuel efficiency for passenger vehicles.



Detailed  procedures  for conducting chassis  dynamometer testing are provided in the

optional  complete  vehicle federal emissions certification method for light heavy  duty

vehicles,  applicable to heavy duty vehicles with a GVWR of 8,500 to 14,000 pounds.

The  chassis emissions test  procedure is  detailed in 40  CFR §86.1816-05, 40  CFR

§86.1816-08, and 40 CFR §86.1863-07. For heavy duty vehicles up to 14,000 pounds,

the heavy duty fuel  efficiency  test procedure described in this  document follows the

provisions outlined in 40 CFR part §86.1863.  The provisions  outlined in 40 CFR part

§86.1863  dealing  with  evaporative  emission  testing,  on-board  diagnostic (OBD)

requirements, smoke emission  requirements, and requirements for measuring criteria

pollutants do not apply.  Although, at the user's discretion, these additional components

can be included in a fuel efficiency test.



For test vehicles exceeding 14,000 Ibs GVWR, there is no pre-existing federal chassis

dynamometer test  procedure.  For these vehicles, the test procedure described in this

document uses many of the precedents established in 40 CFR Part 86, with the exception

of the requirement for a higher  capacity chassis dynamometer.  This procedure provides

new chassis dynamometer requirements to accommodate larger vehicle testing.  In all

cases, the following guidelines should be followed:



   •   Dynamometer coefficients that simulate road-load forces  shall be determined  as

       specified in SAE J2263 and J2264.

   •   Dynamometer power absorption and inertia simulation shall be set as specified in

       40 CFR Part 86-1229-85.

   •   Test instrumentation equipment (including where appropriate, exhaust emissions

       sampling and analytical systems) as  referenced in 40 CFR Part 86.1301-90 to 40

       CFR 86.1326-90 and/or 40 CFR Part 1065 shall be calibrated in a manner that is

       NIST-traceable.

4. Vehicle Selection

Vehicles shall be representative of production fleet vehicles.  The test vehicle must be

appropriate for its service category.  It should have the same vehicle "package," that is,

body  style,  equipment,  number  of axles, gross vehicle  weight rating (GVWR),  and

accessories,  that enable the  complete vehicle to  accomplish the type  of service

(performance,  utility,  durability,  etc.)  for its  intended  application.    Equipment

specifications that can affect fuel efficiency (engine size and type, tire size and type,

transmission size and type, brakes, gear shift  points, rear axle ratio,  air suspension,

lubricant type, idle RPM, ignition timing, wheel alignment,  etc.) must be representative

of how that vehicle is driven on the road, and used to perform work.

                                                                               13

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Test vehicles need not be new, but they must be in good mechanical order and operating

condition,  with no  obvious mechanical or  physical defects that might affect  fuel

efficiency.  If new, the vehicle should be  broken in per the manufacturer's recommended

procedures, at  a minimum.  Refer to the requirements  for mechanical and  operating

condition described  in  SAE J1321  §8.7.9   All  components and  equipment  shall be

calibrated  and  maintained to within manufacturer-recommended specifications.   The

exception is any component that has been deliberately modified as part of the test truck

design.



To  ensure  proper vehicle operability, it  is recommended that the engine and emission

control equipment meet the emissions performance certification for the given model year.



If a heavy  duty vehicle is typically used in combination with a trailer or truck body, the

test will  produce a more comprehensive  fuel efficiency result if the vehicle is tested in

combination with a trailer or truck body.  In  certain  instances, testing with a trailer or

truck body is necessary;  for example, in track testing, to provide the proper payload

required, or when testing the impact of aerodynamic design elements for use in a tractor-

trailer combination vehicle.



If a heavy duty vehicle is tested with  a truck body  or trailer, then the truck body or trailer

shall be appropriate for that vehicle's intended  service. It is recommended to use a trailer

or truck body that is representative in design, function, weight, and dimension, of the type

of trailer or truck body typical for that application. An exception is if modifications to a

trailer or truck body are part of the  vehicle design being tested.  Whenever a trailer or

truck body  is tested with a heavy duty vehicle, the  same trailer or truck body must remain

paired with the test vehicle throughout the duration of the testing program.



Unless otherwise indicated, the following trailer  specifications are recommended for a

typical highway line haul tractor-trailer combination:

    •   dry  van box trailer

    •   2 trailer axles

    •   53'  long, 102" wide, 13'6" high

    •   minimized trailer gap (maximum of 45" depending upon kingpin setting)

    •   11,000 to 14,000 pounds



Truck body specifications shall be appropriate to each intended application.



When selecting a  test vehicle, if the  purpose is to compare its performance to other

vehicles  in that application, then the  vehicles selected shall be closely matched in class,

model year, body style, equipment, fuel  type,  accessories,  mileage, and condition, with

the  exception of any vehicle design options being tested.10



5.  Test Fuel



For vehicles with compression-ignition engines certified on diesel fuel, the test fuel shall

be number  2 distillate ultra-low sulfur diesel  fuel (ULSD). The test fuel will meet fuel

                                                                                14

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specifications outlined in 40 CFR §80.520 for ULSD #2D distillate.  The exception is if

fuel type is a design option being tested.



Specific fuel parameters include:

   •   Sulfur content.                    15 parts per million (ppm) maximum

   •   Cetane index and aromatic content.  Minimum cetane index of 40 or maximum

                                        aromatic content of 35 volume percent.

   •   Flash/Fire point.                    52° C minimum

   •   Water/Sediment.                  0.05% volume maximum

   •   Particulate Contaminant.           10 mg/L maximum

   •   Viscosity KIN/CS at 40°C.         1.9 to 4.1



For vehicles with any Otto-cycle engine certified on gasoline, natural  gas, propane, or

other fuels, the test fuel shall meet the fuel specifications outlined in 40 CFR §86.1313-

94, sections c through f

A supply of test fuel sufficient to complete the test must be procured and fuel parameters

including fuel density analyzed prior to the start of the test. If fuel consumption is to be

measured by the gravimetric method, the following additional test shall be made:

   •   ASTM Test Method D-1298, Standard Test Method for Density, Relative Density

       (Specific Gravity), or API Gravity of Crude Petroleum and Liquid Petroleum

       Products by Hydrometer.



The test fuel must be sequestered once it is procured and analyzed.  If it is necessary to

add additional fuel to the test fuel  supply during the course of the test, another fuel

analysis must be conducted to ensure the test fuel still meets the required fuel parameters.

For each test segment, a record must be kept of the fuel parameters  of the test fuel,

including density.



6.  Test Track Specifications and Requirements

If the option for on-road testing is chosen, the testing shall be conducted on a test track,

not on a public  highway, to provide  greater control of test conditions.  This section

describes the general specifications and conditions for the test track.



6.1 Track Specifications

Setting specifications for the test track  can minimize the effect of a  track's physical

attributes on vehicle performance. The following are specification requirements for a test

track that will give good,  repeatable results, while still allowing for a reasonable number

of track facilities to be used to conduct this test:

   •   Shape. Oval (recommended), figure eight, or serpentine to minimize the effects

       of yaw angle wind effects and lateral forces. Circular tracks are not permitted.

   •   Neutral steering speed.  The radii of the curves in conjunction with the banking

       grade (superelevation) shall be selected to permit a minimum of 40 mph around

       the curves. This can require a superelevation of 2% for curves with a 10,000 foot

       radius or more. For curves with a radius of less than 10,000 feet, the super

       elevation must be consistent with applicable state and federal DOT roadway

                                                                              15

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       requirements. A minimum neutral steering speed is needed to prevent the test

       vehicle from losing forward motion to lateral forces when negotiating a curve

       "hands off."

   •   Length. A minimum of 1.5 miles, with 5 miles or more recommended. A track

       of this length minimizes excessive curve radii and prevents the test vehicle from

       losing forward motion when negotiating curves.

   •   Grade.  The maximum grade change shall not exceed 2% longitudinally, to

       prevent the test vehicle from excessive changes in forward motion due to grade.

   •   Surface. The surface shall be concrete or asphalt, to minimize energy absorption

       effects of uneven or rough pavement.  It is recommended that the friction and

       surface characteristics comply with federal and state DOT specifications

       regarding road condition.

   •   Altitude. The track shall be at an elevation no higher than 4,000 feet above  sea

       level, to minimize changes to air density that may alter the vehicle's forward

       motion, and to prevent unintended changes in engine and subsystem operation.

   •   Maintenance. The test track shall be well-maintained, inspected at least once a

       year, and resurfaced as needed to maintain surface integrity and consistency.



6.2  Track Requirements

The track shall have the capacity to measure and record test conditions, in order to ensure

that a test is  conducted in accordance  with the provisions of this test procedure.  The

following are the minimum requirements needed to conduct a track test:

   •   Weather Monitoring. The track shall be equipped with the capacity to monitor

       ambient conditions (wind direction and velocity, temperature, humidity,

       barometric pressure) during each test.  It is recommended that the weather sensing

       equipment is located on the test track, or at a  weather station within 50 miles of

       the test track. Options for on-site weather monitoring equipment include:  an

       anemometer or a marine-type hand held wind indicator to monitor wind direction

       and velocity11; a thermometer to measure temperature; a barometer to measure

       barometric pressure; and a hygrometer to measure humidity. The positioning,

       etc., of ambient  condition sensors shall be consistent with provisions outlined in

       the Federal Standard for Siting Meteorological Sensors at Airports, FCM-S4-

       1987.  The track shall have the capacity to record this weather information, as part

       of the test record.

   •   Truck Weight Scales. The track shall be equipped with properly calibrated truck

       weight scales (or located within 50 miles of the test track) that conform to the

       most current provisions established by the National Institute of Standards and

       Technology (NIST). As of the writing of this test procedure, these provisions are

       those published  in the NIST Handbook 44 - 2007 Edition, Specifications,

       Tolerances, and Other Technical Requirements for Weighing and Measuring

       Devices. The truck scales must be calibrated annually at a minimum.  It is

       recommended that the truck scales have a National Type Evaluation Program

       (NTEP) Certificate of Conformance.

   •   Portable Scales. If the portable  fuel tank gravimetric method is used, the track

       shall be equipped with properly calibrated portable scales that conform to

       provisions established in SAE J1321 §5.7.1 and §8.4. Scales should have  a

                                                                               16

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       resolution of 0.1% of the expected fuel mass consumed, or better.  Portable scales

       must be calibrated annually at a minimum. Portable scale function should be

       verified with a check weight prior to the weighing operation.

   •   Portable Emissions Monitoring System (PEMS). If the PEMS carbon balance

       method is used, the operators conducting the test shall have the capability to

       properly use and maintain a portable emissions monitoring system (PEMS), as

       recommended by the PEMS manufacturer, and as required by 40 CFRPart 1065.

       This includes providing all equipment and materials needed to properly use and

       maintain the PEMS.  In addition to the electronic flow meter, gas analyzer, heated

       lines, etc., integral to the PEMS, ancillary equipment and materials include zero,

       calibration and span gases; gas pressure and flow regulators and gauges; data

       loggers; all connectors and hoses.  The PEMS and all PEMS-related equipment

       and supplies shall be calibrated and maintained as recommended by the PEMS

       manufacturer,  and as required by 40 CFR Part 1065 Subpart D.  Additional

       requirements governing the use of PEMS are detailed in Section §8 of this test

       procedure.

   •   Speed and Distance Equipment. The test vehicle must be equipped with a

       means to measure speed and distance. A global position sensor (GPS) is

       recommended, as an adjunct to vehicle electronic control module (ECM) data

       and/or speedometer and odometer readings. The accuracy of the odometer and

       speedometer must be verified  and corrections made if necessary. This can be

       accomplished using a stop watch and the track lane length at the specified  speed.

       Reference SAE J1321 §8.12.  The track must be equipped with markers that can

       be positioned to match target speed and distance parameters of the selected drive

       cycle, including gear shift and braking points. Using a global position sensor

       (GPS) is recommended, as an  adjunct to ECM data and/or speedometer and

       odometer readings.



6.3  Track Environmental  Requirements

A track test is not intended to replicate the tightly-controlled environment of a laboratory

test, since a key attribute of track testing is the ability to more closely simulate in-use

operation.  Nor would such tight  controls be feasible on a track test.  However, setting

appropriate parameters  for  ambient  conditions can improve the  repeatability  and

reproducibility of track test results. The following limits allow for reasonable variation in

the ambient conditions under which track tests can occur:

   •   Temperature. Testing shall occur when the ambient temperature is between

       68°F to 86°F (20°C to 30°C).  If the ambient temperature changes by more than

       20°F over the course of the testing, all testing will be repeated. The temperature

       in the fuel tank cannot exceed 160°F.  Reference SAE J1321 §5.7.3. 12 When

       using the PEMS method, a test run shall be invalidated if an ambient temperature

       warning on the PEMS occurs during the test.

   •   Humidity.  Testing can be conducted at any humidity level; however, an optimal

       range is between 35% and 75% relative humidity; 40% is ideal.

   •   Wind.  Testing shall occur when wind speeds are at 12 mph or less, with wind

       gusts no greater than 15 mph.

                                                                              17

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   •  Precipitation. Testing shall occur during conditions of no visible precipitation

      and no moisture on the test track surface, which would contact the tires. No

      visible precipitation is defined as precipitation of 0.1 mm (per hour??) or less.

      Testing shall occur only when the track is dry, and there is no precipitation or fog.



Information about environmental conditions during a test shall be available during or

after the test, to determine the test's validity, and records shall be kept as part of the test

documentation.



7.  Chassis Dynamometer Specifications and Requirements



Detailed procedures to conduct  chassis dynamometer testing are provided in 40 CFR Part

86, SubpartB. If one opts to test to §86.1863, SubpartB can be used.  If a test vehicle

exceeds  14,000 pounds GVWR, then a higher capacity chassis dynamometer may need to

be used.  Recommended specifications for a higher capacity chassis dynamometer are

listed below.



7.1  Chassis Dynamometer Specifications

The chassis dynamometer specifications for testing heavy duty vehicles with a GVWR of

less than 14,000 pounds but more than 8,500 pounds shall  be similar to the requirements

found in 40 CFR Part 86, Subpart B for the testing of light duty cars and trucks. Section

§86.108-00 of the CFR includes provisions for both small  twin roll (8.65-inch diameter)

and large, single-roll (48-inch)  dynamometers. A large, single-roll  electric dynamometer

is preferable, unless a vehicle is more suited for testing on a twin roll dynamometer (e.g.,

if disengaging one of the axles on  a twin-screw  drive axle would create a safety or

operational problem). If a twin roll hydrokinetic dynamometer is used, the results must

be correlated to that of a single roll electric chassis dynamometer.13 For vehicles with a

GVWR greater than 14,000 pounds, the heavy duty chassis dynamometer used to test the

vehicle shall  have a sufficient capacity to test the vehicle  at its rated test weight for the

application.



If the tested vehicle exceeds 14,000 pounds GVWR, the testing organization shall refer to

the following recommended specifications.



    HEAVY  DUTY VEHICLE CHASSIS  DYNAMOMETER SPECIFICATIONS

                    GENERAL  FACILITY INFORMATION

GVWR capability                   >  14,000  Ibs

Rear Axle Weight  Capability     5,000  to  44,000 Ibs

Speed  Range                         0  to 65 mph

Power  absorption                   0  to 500  hp

Power  motoring                     0  to 500  hp

Tractive  Force                     3000 Ibs-f

Roll Diameter                      24 to  72  in

Lab Environment Temperature     68°F to 86°F

Range

Combustion  air  temperature      No

                                                                        18

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control?  (y/n)

Combustion air  humidity         No

control?  (y/n)

                      MOTOR  AND POWER CONTROL

Motor Type

Manual or  automated drive

cycle

Nominal power  (standard)

Nominal power  (maximum)

Drive Torque  (standard)

Drive Torque

                    DC  or AC  motors  (approx range

                    500 hp)

                    Automated

(maximum)

                                    400  hp

                                    500  hp

                                    5000 Ib-ft

                                    8000 Ib-ft

                     ACCELERATION MEASUREMENT

Acceleration, maximum           5 to 15 ft/sec2

Deceleration, maximum           5 to 15 ft/sec2

                       EMISSIONS CAPABILITY

                                    Bag  method,  or  continuous raw

Acceptable types



NOx

PM

HC

CO

C02

Fuel  flow

Fuel  type  capability

                    smpl.

                    Not  required

                    Not  required

                    FID

                    NDIR or  FTIR

                    NDIR or  FTIR

                    Carbon balance

                    Diesel,  CNG, gasoline,

                    propane

7.2  Chassis Dynamometer Requirements

A requirement for either type of chassis dynamometer (single or twin roll) is that it shall

permit the user to convert coastdown data for the test vehicle to the proper horsepower

absorption setting for the chassis dynamometer. A coastdown test must be conducted and

the results converted to dynamometer settings using published SAE procedures.14 15



Coastdown data shall be taken with the vehicle at full test weight to determine the proper

dynamometer settings. Additional details on how to conduct a vehicle coastdown test

and convert the results  to the proper horsepower  absorption setting in  chassis

dynamometer tests is found in Section §12 of this document.



Either type of chassis dynamometer (single or twin roll) shall be equipped with a cooling

fan to provide  cooling air flow to the vehicle  during testing.  Refer to 40 CFR Part

86.107-96 (d) for vehicle cooling fan requirements.  A road-speed modulating fan shall

be used, rather than a fixed-speed cooling fan.



Refer to 40  CFR Part 86.108-79 and 86.108-00  for chassis dynamometer equipment

specifications.  Refer to 40 CFR 86.118-00 and 40 CFR 86.118-78 and 40 CFR Part

86.116-90 through 86.116-94 for chassis dynamometer calibration requirements.

                                                                    19

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Additional details covering the chassis dynamometer test procedure are found in Section

§12 of this document.



7.3  Chassis Dynamometer Environmental Requirements



Testing conditions are consistent with the requirements established in 40 CFR Part 86 for

federal vehicle emissions testing using chassis dynamometers.  These include:

   •  Temperature. Ambient temperature levels shall not be less than 20 degrees C

      (68 degrees F) nor more than 30 degrees C (86 degrees F). Reference 40 CFR

      Part 86.

   •  Humidity.  Testing can be conducted at any humidity level; however, an optimal

      range is between 35% and 75% relative humidity; 40%  is ideal.

   •  Fuel Temperature. Fuel temperatures of the test vehicle shall be controlled, as

      specified in 40 CFR Part 86.107-96 (d).



8. Test Equipment Specifications



Fuel consumption is measured by three possible methods:  A carbon-balance based on

emissions measured in a laboratory test cell, a carbon balance based on emissions

measured by a Portable Emissions Monitoring System (PEMS), or using the gravimetric

method, in which the mass of fuel consumed during the test is directly measured.  The

laboratory test cell is suitable only for use in a chassis dynamometer test, whereas the

PEMS or gravimetric measurements would be best suited for track tests.

8.1 Laboratory Emissions Monitoring System



This test procedure adopts the  requirements for laboratory exhaust gas sampling and

analysis systems established in the federal emissions certification program for Otto and

Diesel cycle engines used in heavy duty vehicles, described in 40 CFR Part 1065. For

equipment and specifications not covered by that citation, 40 CFR Part 86, Subpart N will

apply (specifically §86.1301-90 through §86.1326-90). For this procedure, the provisions

dealing with evaporative emission testing, the OBD requirements, the smoke emission

requirements, and requirements  for measuring particulate matter and NOx do not apply.

However, at the user's discretion, these additional components can be included in  a fuel

efficiency test.



Alternatively for determination of fuel efficiency by carbon balance (e.g., by

measurement of gas flow and CC>2 concentration), it is acceptable to use a field sampling

type "raw" exhaust gas sampling and analysis system, rather than the dilution tunnel

system specified in 40 CFR Part 1065, Subpart B and 40 CFR Part 86, Subpart N.

However, it is important to ensure that intake air flow measurements are done in such a

way as to simulate the trucks in-use air intake system. If direct measurement of mass fuel

                                                                           20

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consumption is chosen in lieu of dilute exhaust CC>2 measurement, the fuel measurement

device shall be accurate to within 2 percent of actual mass fuel flow.

Additional equipment specifications and calibration and maintenance requirements for

laboratory exhaust gas sampling and analysis systems are referenced in 40 CFR Parts

86.314 throush 86.317; 40 CFR Parts 86.319 through 86.322; and, 40 CFR Parts

86.328 through 86.331.



8.2 Portable Emissions  Monitoring Measurement System

General provisions for field testing using PEMS can be found in 40 CFR Part 1065,

Subparts C, D and J.



If the PEMS/carbon balance method is used, the following conditions must be met:

   •   The PEMS must use the same measurement technologies and meet the same audit

       criteria as laboratory instrumentation under 40 CFR Part 1065 Subpart D, as

       applicable.

   •   The carbon balance method must be conducted to comply with EPA's regulations

       as outlined in 40 CFR Part 600, and 40 CFR part 86 subpart N.

   •   Carbon balance fuel efficiency must be calculated using the method outlined in

       SAE Standard J1094a.16

   •   The exhaust routing must meet the requirements specified in 40 CFR Part 1065 to

       keep crankcase ventilation gas (blowby gas) in the exhaust stream.



Specifications for the PEMS flow meter, analyzer, and data logging requirements are as

follow:

[Reserved]



8.3   Gravimetric Fuel Consumption Measurement System

General provisions  for field testing using portable  fuel tanks and  the gravimetric

consumption measurement system can be found in SAE  J1321  §5.7.1, §5.7.3,  and §8.4.

A portable overhead hoist can be employed to  move the portable tank and position it on

the scale and on the test vehicle.  It is recommended to mount a frame to the test vehicle

to secure the portable tank, and to install self-sealing quick connects and  check valves

with supply fittings and check valves mounted directly to the fuel  tank.  Fuel hoses

leading to and from the tank should be primed beforehand to prevent errors  due to filling

the  volume of the hoses and also to  prevent air  entrainment.   Quick-connects will

facilitate the rapid installation and removal of the portable fuel tank.  The tank  should be

positioned on the vehicle to minimize any impact to the vehicle's aerodynamics during

coast down testing and track testing. The portable fuel tank for the test vehicle shall be

fueled from the same dispenser during the entire test to ensure consistent fuel grade  and

quality. See Sections §5 and §11.8  of this documents for  details on fuel and fuel analysis

requirements.

                                                                            21

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Consistent with SAE J1321, after conducting pre-test vehicle and equipment check-ups

and the required warm-up, the portable fuel tank is topped off and weighed.  The weight

should be checked a minimum of two times to ensure accuracy.  It is recommended that

the portable tank  is stabilized before and during weighing to avoid weight fluctuations

due to fuel sloshing.  After weighing, the fill cap is secured, and the weight recorded.

Fuel from the portable fuel tank is used only during the drive cycle.  It is not used during

pre-test checks or warm up laps, and it is not used to move the vehicle to the test starting

point, or from the test finish point.



After the portable tank is filled and weighed, it is moved from the filling and weighing

area to the test vehicle.  A portable hoist is recommended. The portable fuel tank is

mounted on the test vehicle and the fuel line connected to the test vehicle using hoses and

fittings designed for this purpose. The portable tank fuel connections must permit the test

vehicle driver or an in-vehicle assistant to instantaneously switch the vehicle's fuel

supply from the permanent fuel tanks to the portable fuel tank, and vice-versa. The

configuration should also prevent any backflow into the measurement tank after that tank

is switched off-line.



After completing  all the necessary pre-test requirements, the test vehicle is moved to the

marked starting point and parked, with engines stopped. The moment the test begins, the

test vehicle's fuel supply is switched to the portable tank,  and  disconnected from the

portable tank the  moment the test ends.  The test vehicle is returned to the filling and

weighing area, and the portable tank is disconnected, recapped, removed and reweighed.

The difference  in the  weight of fuel consumed  during the test is calculated and the

density of the fuel (measured during the fuel analysis) is used to determine the volume

(gallons) of fuel used.  Sections  §14 and §16.2 of this document provide details for the

fuel efficiency calculation using the gravimetric method, and a sample calculation.

9.  Drive Cycle Selection

9.1 Drive Cycle Selection Criteria

Fuel efficiency is known to be strongly related to the duty cycle (also known as the "drive

cycle")  of a vehicle.  In turn, the duty cycles of heavy-duty vehicles vary greatly by

application.   Thus, the test  protocol requires separate  duty  cycles  for each  vehicle

application.   Included here  are  descriptions of possible  drive  cycles the following

applications:



Tractor-trailer combination line haul and regional haul truck;

Local pick up and delivery vehicle;

Transit bus;

Neighborhood refuse truck;

Utility truck; and

                                                                               22

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Intermodal (port) drayage truck.



This  document will  be  updated with  additional  heavy  duty  vehicle  types and

corresponding drive cycles as they are developed.



Heavy duty vehicles have widely  varying payload and accessory power requirements,

depending upon the intended application.  This test procedure includes specific payload

and accessory load power requirements in the drive cycle sections for each of the heavy

duty vehicle applications included in this document.  It also  extends the test weight

basis/test equivalent test weight tables found in 40 CFR Part 86.



The drive cycles are designed to be used on either a test track or a chassis dynamometer.

They  were  developed to  simulate "real world" operations.   The  following sections

describe the different drive cycles and corresponding vehicle applications.



Speed-time points for  these drive  cycles along with summaries of cycle statistics will

appear in an updated version of the  appendices.



9.2  Highway Line Haul

The highway line haul cycle simulates a combination tractor-trailer commercial freight

delivery truck, operating in  interstate, predominantly highway, operation.  This type of

vehicle operation is characterized by long  trip lengths, higher average speeds,  more

steady-state type engine operation, and overnight rest stops, which in some instances

involve long-duration idling.17 The vehicles are powered by heavy duty engines typically

used in class 8 trucks  (33,001 pounds GVWR or greater).  Typically, the tractor has a

sleeper cab with 3 axles; it is attached to a tandem axle trailer. Depending upon the type

of freight carried, the trailer can be a dry van box, reefer, tanker, car carrier, livestock

van, flat bed, or other.  A dry van  box semi-trailer is recommended for this test,  except

when testing for applications that require a specific trailer type.



This document describes two options for a highway line haul  drive cycle.  Both are

modifications  of the Cruise mode of the California Air Resources Board (ARE) Heavy-

Heavy Duty Diesel Truck (HHDDT) emissions test, a four-mode test to represent heavy

truck  operation, developed  using data from 171  instrumented heavy  duty  trucks.18

Although the ARB test includes an idle, creep, transient, and cruise mode, only the latter

is used as the basis of the highway  line haul drive cycle. This is because data to develop

the ARB test was collected from a  random selection of all heavy duty trucks.  However,

line haul trucks are a unique subset of heavy duty trucks that spend the majority of their

miles at highway speed.



The first drive cycle  option was developed by EPA  for fuel efficiency  and emissions

track  testing  of combination tractor-trailers.    In this  cycle,  the most  significant

modifications  made  to the  Cruise module were to add in some transient and idling

operation,  and  to  reduce  deceleration and acceleration  rates.   Deceleration and

acceleration rates in the Cruise module are too severe for a class 8 combination tractor-

trailer,  especially  when loaded   to typical weights of 33,000 to  66,000 pounds.

                                                                               23

 image: 

















Additionally, if tested on a chassis dynamometer, one risks damaging the dynamometer

and the vehicle's brakes.

19

A graphic of this version of the highway line haul drive cycle is provided below in figure

2.

Figure 2

                 CO-

                 CO

                 JO

                 |Q •

                  0

                     r?

                               High/vary Line Haul

                           >Q     JO

Another version of a highway line haul cycle, suitable for use only on a chassis

dynamometer, was created by Southwest Research Institute, using input from a group of

stakeholders, including EPA, Northeastern States for Coordinated Air Use Management

(NESCAUM), several truck and engine manufacturers, state organizations, and others,

for a NESCAUM heavy truck fuel efficiency modeling and simulation project. It is

similar to the first option shown above, although top and average speeds are increased,

there are grade impacts, there is less transient operation, and idling is handled in a

separate cycle. A graphic of this version of the highway line haul drive cycle is provided

below in figure 3.

Figure 3

                                                       I ,'

                SCO

                      tOOD

                                  2000

                                        2SOO

                                              30DO

                                                    3SOO   JDOO   .1500   5000

                                                                              24

 image: 

















Each of these cycles may be considered, with the potential to combine features of each

into a final Highway Line Haul cycle. Data and input on payload and accessory load will

also be considered, to develop these aspects of the drive cycle (discussed in Section xx).



9.3  Regional Haul

Regional haul operation is similar to highway line haul, the primary distinction being that

regional  haul has relatively shorter  trip lengths, and includes some suburban-type

operation, with lower average speeds, relatively more frequent congested driving, and no

(or infrequent) overnight  stays.   If purchased new for this application,  the tractor is

typically a day cab, without sleeper accommodation.



EPA is still  selecting options for this drive  cycle. One promising option is to integrate

segments  of the Transient mode of the ARB HHDDT test into the finalized Highway

Line Haul cycle (which is based upon the Cruise module of the ARB  HHDDT test), to

create a single drive cycle of sufficient duration and complexity.



Analysis and "filtering" of the ARB Cruise  and Transient modes has been conducted by

West Virginia University.  This work,  combined with input on the line-haul cycle, could

serve  as the basis for a regional  haul drive  cycle.   EPA will begin to formalize

recommendations for the regional haul cycle and include specific options  in subsequent

drafts of this protocol.



9.4  Local Pick Up and Delivery

The local pick up and  delivery cycle simulates a package, parcel, or beverage delivery

truck  operating in urban-type driving, to provide local pick up and delivery service to

residences and businesses. This type of truck operation is characterized by very frequent

stops and starts, with limited "stem" highway driving to and from the distribution center.

The vehicles are  powered by heavy duty engines typically used in class 4 to 6 trucks

(14,001 to 26,000 pounds GVWR), although some vehicles may be as light as class 2b or

3.  The vehicle is typically a  single unit truck or a chassis/truck body combination, with 2

axles.



EPA is still  collecting information on local  pick up and delivery candidate drive cycles.

The parcel delivery working group of the Calstart-Weststart Hybrid Truck Users Forum

(HTUF) instrumented a small number of parcel delivery trucks  in the  Florida area, and

developed two parcel delivery drive  cycles.  One  represents a class 4 residential delivery

truck, and one represents  a  class 6  commercial delivery truck.   The major differences

between  these two drive cycles are the rate of acceleration, average speed,  number of

stops, and percent of stops that are idle or engine off.



Graphics of the two parcel delivery drive cycle candidates are provided below in figures

4 and 5.

                                                                               25

 image: 

















Figure 4: ~ HTUF Class 4 parcel delivery cycle

Figure 5:~ HTUF Class 6 parcel delivery cycle

                                   HTUF Class 6 PDDS - Full Cycle

                 1  160 319 478 637 796 955111412731432159117501909206822272386254527042863302231813340349936583817

                                           Time (sec.)

EPA  is also instrumenting parcel delivery trucks  for its  hydraulic  hybrid development

program.  After this data is collected and analyzed, EPA can determine what changes, if

any, might be made to the HTUF drive cycles, and whether we want one single cycle, or

whether we could  develop  a  formula that  allows a testing organization to chose a

weighted  combination  of  more than one  cycle,  depending  upon vehicle service

characteristics.   Data and  information on payload  and  accessory load  will  also  be

considered.

                                                                                    26

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9.5 Neighborhood Refuse Truck

The neighborhood refuse truck drive cycle simulates a trash collection and compacting

truck, operating in urban-type driving, to provide residential and commercial solid waste

collection within  a local community.  The vehicle operation is characterized by very

frequent stops and starts, with limited "stem" highway or suburban driving to and from

the refuse drop-off site.  During its operation, the engine  or other power source is

typically  used to  operate  hydraulic and/or other lifting, compacting,  and dumping

functions.  A significant amount of the fuel  used  by neighborhood refuse trucks is

consumed by these non-motive functions.  These  vehicles are powered by heavy duty

engines typically used in class 7 or class 8 trucks (greater than 26,001 pounds GVWR).

The typical refuse haul  vehicle is a chassis/truck  body combination with a single axle

tractor and either a single or tandem axle trash loader/ packer body.



One candidate neighborhood refuse  truck drive cycle was developed by the National

Renewable Energy Laboratory of Department of Energy  using data collected by Ohio

State University, from instrumented neighborhood refuse trucks in 5 different cities.  It

includes vehicle operation during collection, dumping, and driving to and from the dump

and neighborhood sites.



A graphic of this candidate neighborhood refuse truck drive cycle is provided in Figure 6.

Due to the complexity of this refuse hauler cycle, this cycle  should be performed on a

heavy duty vehicle chassis dynamometer only.



Figure 6

                 70

                 50

               Q.

                 20

                 10

                             500

                                        1000

                                     Time (s)

                                                   1500

                                                              2000

                                                                              27

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EPA will request stakeholder input on this drive cycle, including payload and accessory

load.



9.6 Utility Service Truck



The utility service truck drive cycle simulates a public utility, cable, or telecom service

truck operating in urban-type driving, to furnish electricity, gas, water, or telephone

service to local businesses and residences by conducting service calls and fixing

"trouble" on utility lines and junctions.  Vehicle operation is characterized by periods of

using the engine or other power source to operate hydraulic aerial lifts, and/or to supply

electrical power to the grid and/or to operate on-board equipment. A significant amount

of the fuel used by utility service trucks is consumed during these non-motive functions.

The vehicles are powered by heavy duty engines typically used in class 6 or 7 trucks

(19,501 to 33,000 pounds GVWR). A typical vehicle is a chassis/truck body combination

with a single axle tractor and a single axle truck body equipped with outside-accessible

compartments and a 30' to 50' hydraulic aerial lift (boom) for lifting workers and tools.



A potential  utility service truck cycle is  the CILCC drive cycle, a  composite cycle

developed  by  DOE/NREL, Eaton,  and  International  Truck  and  Engine.    These

organizations developed  their cycle  by extensive and iterative analysis that compared

several  candidate drive cycles  against  key performance  needs of hybrid electric urban

delivery vehicles.  Eaton and Southwest Research Institute have used this cycle in their

fuel efficiency tests of hybrid utility service trucks.



Eaton and  SwRI also  developed hydraulic and electric test cycles to measure power

demand for the aerial lift and powering the grid, which could be incorporated into this

cycle, along with payload requirements.



The CILCC cycle is shown below, in figure 7.

                                                                                28

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                          LL-Li

j_

                    "o     TO    IITC    1500



         Figure 7



9.7 Transit Bus

The transit bus cycle simulates a 35' to 40' bus operating primarily in  local areas, to

provide frequent-stop passenger service.  This vehicle operation is characterized by low

average speed and  regular, frequent stops, with relatively short  trip  lengths between

stops.  Vehicles typically lack  facilities for long-distance operation (e.g., no onboard

restrooms or large luggage compartments).  However, passenger comfort and information

is essential.  Transit buses use the engine or other power source to power internal and

external signs, interior lighting, and hydraulic lifts, and to supply heat, ventilation, and air

conditioning  (HVAC).   A significant amount of the fuel used by  transit buses is

consumed by these non-motive "hotel loads."  They are  powered by heavy duty engines

typically used in class 7 or 8 trucks (over 26,000 pounds GVWR). A typical transit bus is

a single body construction with 2 axles. It can accommodate over 15 passengers, and is

equipped with 2 sets of doors.



There  are  significant  differences  between  transit  buses operating  in  suburban

neighborhoods, and transit buses operating in more urban neighborhoods.  In recognition

of the differences, two different candidate drive cycles may be chosen for testing transit

buses:  the Manhattan bus cycle and  Orange County bus cycle, representing  urban and

suburban transit service, respectively.



The Manhattan Bus  Cycle was developed based upon the driving  patterns  of buses in the

Manhattan core of New York City. The cycle, originally published as a transient chassis

dynamometer test cycle  for urban transit buses, is characterized by frequent stops and

very low  speed.  The maximum speed is 25.4  mph; the average speed is 6.8 mph

(ll.Okm/h).



The Orange County Bus Cycle was developed by West Virginia University based upon

the  driving patterns of urban transit buses in the Los Angeles area.  The cycle, originally

                                                                              29

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published as a  chassis dynamometer test  cycle  for  intermediate speed transit bus

operation, has a maximum speed of 41.4 mph and an average speed of 12.5 mph.



The speed-time points for the Manhattan and the Orange County bus cycles can be found

in Recommended Practice for Measuring Fuel efficiency and Emissions of Hybrid-

Electric and Conventional Heavy duty Vehicles, SAE  Surface Vehicle Recommended

Practice J2711.  A graphic depicting each of these cycles is found in Figures 8 and 9.

Due to the complexity of these bus drive cycles, these cycles should be performed on a

heavy duty vehicle chassis dynamometer only.

Figure 8: --Orange County Bus Cycle

                                                                             30

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Figure 9: ~ Manhattan Bus Cycle

Determining Which Bus Cycle to Use

Assuming that these candidate cycles are accepted, in order for the selected drive cycle to

be as close to the intended use of the  vehicle as possible, there are certain criteria to

determine whether the Manhattan or Orange County drive cycle should be used for a

specific vehicle test.



Two major factors that determine transit bus performance and for which data are readily

available are  average route speed and percent idle ("stopped") time.  Of these, average

route speed is the most significant discriminator in predicting performance.  These two

parameters are combined into  an index that determines which  of the two drive cycles

shall be used to test the fuel consumption of a specific transit bus model.



The  midpoint between the average speeds  on the two cycles is  9.58 mph,  and  the

midpoint of percent idle is 28.5%.  In the combination of these two  parameters,  the

average speed is given twice the weight of percent idle.  By  equating the ranges of the

two quantities and after normalization the following formula is obtained:

   Cycle Index = 0.013 x (percent idle) + 6.025 H- (average speed in mph)

If the cycle index  for the proposed  average  of all  anticipated routes is greater than or

equal to 1, the Manhattan cycle shall be used.  If the cycle index is less than 1, the Orange

County cycle  shall be used.



As an example, the Cycle Index for a bus fleet with a predicted fleet average speed and

idle time exactly that of the Manhattan cycle would be the following:



                         0.013 x (36) + 6.025/6.83 = 1.35



The Cycle Index for a bus fleet with a predicted fleet average speed and idle time exactly

that of the OCTA cycle would be the following:



                         0.013 x (21)  + 6.025/12.33 = 0.76

                                                                              31

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The average predicted route speed used for this analysis is for the buses while in-service,

and does not include driving to begin the route or to return to the depot after the service

has been completed.



In some cases, the intended service for a particular vehicle may be a route that more

closely  resembles a combination of the Manhattan Cycle and the Orange County cycle

than it does either one. Users of this test protocol have the option of running a complete

set of tests with each cycle, then reporting the results as a weighted value of the results

from each cycle.



Payload (passengers) and accessory loads for transit buses are significant, especially the

impacts of air  conditioning, heating and defrosting.  Power can also be required to lower

and raise the bus to accommodate passengers getting on and off, during typical operation.

Load factors need to be determined for the transit bus cycle. Work to define these loads

started  during  the  development  of the Recommended Practice for Measuring  Fuel

Economy and Emissions of Hybrid-Electric and Conventional Heavy duty Vehicles, SAE

Surface Vehicle Recommended Practice J2711, and should be considered as  a starting

basis for continued development of these load factors.



9.8 Intermodal Drayage  Truck



The intermodal drayage truck cycle simulates a combination tractor-chassis freight truck

operating in predominantly local, urban-type driving with relatively short trip lengths.

The vehicles provide intermodal cargo  drayage by shuttling ocean-going freight

containers among marine terminals, chassis and container depots, rail terminals, and local

consignees. The operations are characterized by periods of extended creep idle or idle

while waiting at distribution hubs, with limited highway and suburban driving between

destinations. Drayage trucks are powered by heavy duty engines typically used in class 8

trucks (33,001  pounds GVWR or greater). Typically, the tractor will have  3 axles. The

chassis is a framework equipped with 2 axles, on which an ocean-going freight container

is loaded. Chassis can have a sliding adjustable center beam to fit containers of either 20

to 28 feet, or containers of 40 to 48 feet. The latter size is more common.



A candidate intermodal drayage truck cycle was developed by the  University of Texas

based upon a number of instrumented trucks operating in the Port of Houston area.   A

graphic for the cycle is found in Figure 10.

                                                                               32

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                               VI

il. n

Figure 10



Additional input and data is needed to refine this drive cycle, including data from other

major port areas (POLB/POLA, NY/NJ), and to develop payload and accessory loads.



10. Accessory Load

Accessory load refers to  vehicle power requirements needed to operate equipment,

accessories, and other implements that are essential to the intended vehicle use.  These

power requirements are considered a "load" on  the  engine  (or other vehicle  power

source), and must be  accounted  for when evaluating vehicle  fuel efficiency.  For the

purposes of this  test  procedure, the following engine/operating components are not

considered "accessories" and the loads will not be measured separately:

    •   Air compressor

    •   Water pump

    •   Engine cooling fan

    •   Power steering

    •   Power brakes



The following sections describe the main accessory functions essential to the mission of

many heavy  duty vehicles.   The power needed  to  provide  these functions must be

accounted for in  the fuel  efficiency test as  an accessory load.   The heavy duty  fuel

efficiency test  protocol will require the  following accessory loads  be used during a

specific portion of the drive cycle. EPA is still gathering information to determine what

the best options  are for including accessory loads  and encourages suggestions from

readers  of  this document.  EPA  will  include those  recommended requirements in

subsequent versions of this protocol.



10.1  Heating and Ventilation, Defrosting

Heating and ventilation refers to loads associated with passenger comfort that do not

require  operation  of the refrigeration cycle  of the air conditioner.  Heating requires a

source of heat (typically waste heat from the engine cooling system, but not necessarily)

plus operation of a blower motor with air circulation fans.  Ventilation requires only

operation of the blower motor and air circulation fans.  Defrosting requires a defroster

fan.

                                                                              33

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10.2 Air Conditioning

Air conditioning refers to loads associated with passenger comfort that require operation

of the refrigeration cycle of the air conditioner. The air conditioning load may include

the power required to  operate a compressor (pump), an evaporator (condenser), and a

blower motor with air circulation fans.



10.3 Power Take-off (PTO) or Other Vocational/Service Work

Load

Power take-off refers to loads associated with the operation of mission functions on a

vocational or service truck.  For example, hydraulic load to operate the loading lift arms,

hopper compacting, and dump operations on a neighborhood refuse truck; hydraulic load

to operate the aerial lift on a utility service truck; and, electric load to simulate supplying

electrical power to the grid on a utility service truck.

10.4  Lamps and Lights

Lamps and lights refer to loads associated with the operation of headlights, all other

exterior vehicle lights (tail light, brake light, marker light, hazard light, turn signal light,

license plate light, identification light, clearance light, dome light, etc.), and lights on

instruments and gages.

10.5 Miscellaneous

Refers to accessory loads not otherwise specified, but typical for a given heavy duty

vehicle's operation, including electric windows,  electric fuel pump, radio, and electric

wipers.

10.6 Drive Cycle Load Requirements

Work has started to develop  accessory load power requirements.20 Substantially more

data and input is needed to determine: 1) the power draw of accessory loads for heavy

duty vehicles; and, 2) the operational  characteristics of each heavy duty vehicle, to

determine "typical" hours  and intensity of operation for each accessory function.  EPA

requests specific comments on  drive cycle load  requirements for each drive  cycle

described above.



Highway Line Haul Accessory Load

[Reserved]



Regional Haul Accessory Load

[Reserved]

                                                                           34

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Local Pick Up and Delivery Truck Accessory Load

[Reserved]



Neighborhood Refuse Truck Accessory Load

[Reserved]



Utility Service Truck Accessory Load

[Reserved]



Transit Bus Accessory Load

[Reserved]



Intermodal Drayage Truck Accessory Load

[Reserved]





11.  Vehicle  Payload and Test Weight

The vehicle  test weight is the loaded vehicle weight, as measured at the start of each

complete drive cycle for each vehicle test.  This weight shall remain constant for each

drive cycle for the duration of a vehicle test/s.  The vehicle test weight is intended to

simulate typical  operation for the heavy duty truck application being tested.



Vehicle test weight is generally the vehicle curb weight (weight of empty vehicle without

passengers or payload, but including oil, gas, coolant, and other standard equipment),

plus the weight  of the driver, and a specified payload or cargo weight. In the case of a

transit bus, it includes the weight of a specified number of passengers.



The vehicle test weight also includes the weight of the PEMS, plus  span and calibration

gases, or the portable fuel tanks, plus test fuel.



For heavy duty vehicles under 14,000 pounds GVWR (up to classS), the vehicle test

weight is the test equivalent weight specified in 40 CFR Part 86, (specifically §86.129-

94).



For all other heavy duty vehicles, a vehicle test weight is stipulated for each of the drive

cycles in this test procedure.  The test weights for each drive cycle in this test procedure

are developed taking  into  consideration vehicle GVWR,  typical  payload (or other

appropriate weight  metrics), average percent empty miles, and weight fluctuation due to

typical cargo loading and unloading patterns.



PAYLOAD VALUES:

                                                                            21

Highway line haul and regional haul: GVWR is 80,000 pounds. Industry data suggests

an average annual cargo weight of about 36,500 pounds for large over-the-road trucks.

Assuming a typical tractor and enclosed van trailer with a curb weight range from 28,000

                                                                            35

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pounds to 32,000 pounds (16,000 to 18,000 pounds for the day cab or sleeper tractor, and

12,000 to 14,000 pounds for the dry van or refrigerated insulated trailer), the cargo

comprises from 70 percent to 76 percent of payload capacity.  This information is

summarized in Table xx, below:

Curb  Weight   Payload  GVWR       Payload

 (tractor  &                           Capacity

trailer)



    28,000      36,500    80,000     52,000

    30,000      36,500    80,000     50,000

    32,000      36,500    80,000     48,000

Percent

Load

   70%

   73%

   76%

Total

Loaded

Weight for

Test

   64,500

   66,500

   68,500

Unused capacity is due to empty hauls, non-revenue miles, and loads that "cube out"

before they "weigh out."  Given this range, a recommended payload for testing is 75

percent of payload capacity.



Local pick up and delivery vehicle: GVWR and payload depends upon the intended cargo

and vehicle configuration (parcel, beverage). The vehicle is gradually emptied during the

execution of its duty cycle.  A simple approach for a recommended testing payload could

be to consider that the vehicle spends roughly half its miles empty, or a 50 percent

"effective" payload.  However, the vehicle may be volume-limited rather than weight-

limited, so the 50 percent would be from volume capacity.  More data is  needed on

typical payloads for different types of local pick up and delivery vehicles.



Neighborhood refuse truck. GVWR can vary between 52,000 to 72,000 pounds.  The

vehicle is gradually filled during the execution of the duty cycle. A simple approach for

a recommended testing payload could be to consider that the vehicle  spends roughly half

its miles full,  or a  50 percent "effective" payload. However, the vehicle  may be volume-

limited rather than weight-limited, so the 50 percent would be indexed from a volume

capacity. More data is needed on typical payloads for different types of  neighborhood

refuse trucks.



Utility service truck. GVWR varies between  16,001 and 33,000 pounds.  Truck weight

includes the "payload" weight of the aerial lift and other equipment.  More data is needed

on GVWR and payload to develop a recommended payload for testing.



Municipal transit bus: Typical GVWR of 19,001 to 26,000 pounds.  A suggested

payload for testing is curb weight, plus driver, plus 150 pounds multiplied by one-half the

seated passenger count.  This recommendation is from SAE J2711, §6.3.3.22



Intermodal drayage truck: GVWR of 80,000 pounds.  Industry data suggests a typical

cargo weight of about 40,000 for ocean-going containers (based upon agricultural loads).

Assuming a tractor, chassis and 40'  container with a curb weight of about 32,000 to

34,000 pounds (16,000 to 18,000 pounds for a tractor; 8,000 for a chassis; 8,000 for an

empty container), the cargo comprises about 83 to 87 percent of the remaining 46,000 to

48,000 pounds payload capacity.  Assuming that the ocean-going containers are empty

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for nearly half their trucked miles, this would bring the effective average weight to

20,000 pounds,  or about 42 to 43 percent of rated payload. More data is needed on

GVWR and payload to develop a recommended payload for testing.

11.1  Test Equivalent Weight

The  test equivalent test weight  is the normative  weight at which the test shall  be

conducted, when using  the  chassis dynamometer method.   This  weight is used to

determine dynamometer inertia weight settings.  Test equivalent weight is based upon the

vehicle test weight (but not to exceed 250 pounds below the vehicle test weight).  For all

heavy duty vehicles above 14,000 pounds GVWR, refer to the following table:





        Vehicle Test Weight From Drive Cycle (Ibs)    Test Equivalent Test Weight (Ibs)



        13,751 to 14,250                       14,000



        14,251 to 14,750                       14,500



        14,751 to 15,250                       15,000



        15,251 to 15,750                       15,500



        Numerical pattern repeats up to and

        including....



        80,251 to 80,750                       80,500



        80,751 to 81, 250                      81,000



        81,251 to 81,750                       81,500



For all heavy duty vehicles below 14,000 pounds, refer to the test equivalent test weights

found in 40 CFR Part 86 (specifically §86.129-94).



11.2  Test Fuel Weight and Volume

In accordance with SAE J1321, maintain fuel volumes as consistently as possible over

the course of the test, to minimize random weight variation.



The amount of test fuel  in the vehicle fuel tanks shall be topped off at the beginning of

each test day. Ideally, this will ensure that tests will be conducted  with an initial fuel

volume of between 50 and 75 percent of the total capacity of the vehicle fuel tank.



If the fuel efficiency test is conducted using the gravimetric method with portable fuel

tanks, the weight of the  portable fuel tanks including fuel must be considered in loading

the vehicle to its required test weight.

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Portable tanks shall be topped off before each test, and the weight recorded as per Section

xx of this test procedure.

12. Test Set-Up Procedure



12.1  TestPayload



Where a test payload is required to meet vehicle test weight requirements, the payload

shall be evenly distributed throughout the trailer (or bus body) and the over-axle loads

must be proportional with federal over-axle weight limits.23 For example, if testing at

80,000 pounds, the payload would be distributed to achieve a weight of 12,000 pounds

over the steer axle, 34,000 pounds over the drive axle, and 34,000 pounds over the trailer

axle. If testing the same vehicle at 65,000 pounds, the payload would be distributed to

achieve a weight of approximately  12,000 over the steer axle (since the payload does not

affect the steer axle that much), 26,500 pounds over the drive axle, and 26,500 pounds

over the trailer axle. It is recommended that the test payload be secured by strapping

down then blocking the payload with nailed-down chucks, so that the payload will not

shift during the test.  Payload must not change during a test.



The vehicle must be weighed using properly calibrated truck weight scales that conform

to the most current provisions established by the National Institute of Standards and

Technology (NIST). It is recommended that the truck scales also have a National Type

Evaluation Program (NTEP) Certificate of Conformance.



12.2  Tire Pressure

Tires  shall be representative of  a typical (e.g., best-selling) tire  for a given vehicle

application, unless a special tire characteristic (e.g., low rolling resistance)  is a condition

being tested.



Tire pressure shall be adjusted at cold  condition as needed before pre conditioning, and

tested to the tire manufacturer's recommended maximum cold inflation pressure.  Tire

pressure shall also be measured at the end of each completed test run to ensure that, at a

minimum , the inflation pressure is consistent with the starting cold pressure.



12.3  Mechanical Preparation of Test Vehicle

Vehicles shall be representative of production fleet vehicles. Test vehicles need not be

new, but they  must be in  good mechanical  order  and operating condition.   All

components  and equipment shall  be calibrated and maintained to within manufacturer-

recommended specifications. The  exception is any component that has been deliberately

modified as part of the test truck design.



Vehicles shall be mechanically prepared and maintained  in accordance with SAE J1321,

Sections  §8.6 to  §8.10.  Vehicles  must not have any mechanical or  physical defects that

                                                                              38

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may affect fuel efficiency.  Vehicles must not have any fluid, exhaust, or air suspension

leaks.  There must be a visual inspection of the tires prior to each test day, to detect any

signs of tire or wheel damage or unusual wear.



The air cleaner monitor and engine fault codes must be checked prior to the test, and any

abnormal  conditions must be corrected, to ensure that the vehicle is in proper working

order. It is recommended that the crankcase, differential, and gear lubricant be removed

and replaced with fresh lubricant prior to the test.



Test vehicles shall have accumulated a minimum of 2,500 miles prior to testing (10,000

miles are recommended to properly break in a new vehicle).



If the test method uses  the carbon balance method of fuel consumption measurement,

follow the additional vehicle preparation requirements in CFR 40 §86.131-90.



Vehicles must be fueled from the same fuel dispenser during the entire test to ensure

consistent fuel grade and quality. Empty the test fuel tanks by draining,  or by vehicle

operation, before filling with test fuel.  Refer to CFR 40 §86.132-90.  If a removable fuel

tank is being used, it shall be filled only with the test fuel.  Refer to  Sections §5.7.1,

§5.7.3, and §6.3 of SAE J1321.



If a PEMS is being used, refer to 40 CFR Part 1065  Subpart D for PEMS system set up.

If using the carbon balance method with either a PEMS or laboratory gas analyzers, all

detectable sources of exhaust gas leaks must be sealed or plugged.



Records of vehicle identification and condition must be kept. Refer to SAE J1321 §4 and

the  referenced Type II Test Data Forms,  and the appendices of this  document for more

details. Vehicles must be weighed before the test to ensure proper test weight, and over

axle weighting, and weight records must be maintained.



12.4  Vehicle Preconditioning

Vehicle preconditioning warms the engine and exhaust emission control equipment, and

raises vehicle operating  temperatures,  so the vehicle is warmed up.  Ideally, the engine

coolant, oil and drivetain lubricants should reach an operating temperature that would be

consistent with those expected during multiple repetition of the associated test cycle.  To

accomplish these objectives, the test vehicle shall be  driven through a warm up cycle

prior to the test.  The warm up cycle shall consist of driving the vehicle at least one time

through the drive cycle that will be used for the test, or 60 minutes, whichever is greater.

Hybrid vehicles may require a lengthier warm up time, to establish an equilibrium state

of charge  (SOC) in the rechargeable energy storage system (RESS),  such that the initial

and final SOC values during the subsequent test cycles will be within the  stated tolerance.

Refer to the following sections for more details.



The test shall commence between 10 and 30 minutes after completion of the warm up.

Gas analyzers must be re-calibrated during the interval between warm up  and test start.

                                                                               39

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Intervals between test cycles shall be between 10 and 30 minutes. Gas analyzers shall be

checked after completing the test cycle to ensure that excessive drift hasn't occurred.



If there is any change (i.e.,  equipment failure or vehicle modification) in the test vehicle

during testing, all testing will be repeated.



For vehicles equipped with a diesel particulate filter, a manual regeneration of the diesel

particulate filter shall be conducted prior to testing.



12.5  Hybrid Vehicles - Additional Vehicle Conditioning

If the vehicle is a hybrid,  additional  vehicle conditioning is necessary to establish an

"equilibrium" state of charge (SOC) in the rechargeable energy storage system or RESS.

State of charge is a measure of the amount of energy stored in an RESS, expressed as a

percent of the total energy storage  capacity of the RESS (battery, flywheel, hydraulic

accumulator,  capactor, etc.).



A stable SOC ensures that  the energy stored in the RESS will not fluctuate  too widely

during the test.  If the energy in the storage device fluctuates too widely during a test,

then the amount  of energy that the RESS provides to the vehicle relative to total vehicle

fuel consumption will be  atypical, and  measured vehicle  fuel efficiency will not be

representative of that vehicle's true operation.  To measure fuel  consumption that is

within +/- 3 percent  of a vehicle's true, representative fuel  consumption, the change in

energy stored in the RESS should be less than +/- 1 percent of the  total fuel energy

consumed during a test cycle.24  A stable SOC is within a stated tolerance for the initial

and final SOC values during a test cycle, as described below.



To accomplish this, the hybrid vehicle shall be operated (driven) at least twice through

the  drive cycle that will be used for the test in order to verify that the initial and final

SOC values are within the stated tolerance.  This vehicle operation can count toward the

requirement for warm-up laps, provided that the test occurs within the time required from

completion of warm up lap.



If the  selected drive cycle results in a net increase or decrease in the SOC, then the initial

SOC of the RESS may be adjusted externally following a trial-and-error approach using

the specific procedures detailed below.



If the  energy  storage capability of the RESS falls below the minimum level specified by

the  manufacturer, testing data generated with that vehicle should  be discarded and the

vehicle should be repaired or replaced prior to conducting additional testing. (SAE J1711

§4.1.2.3.)



Specific preconditioning information for  different types  of hybrid vehicles is described

below.

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Hybrid Electric Vehicles with Batteries

Off-vehicle charging of the battery  pack is permissible in order to achieve the desired

"equilibrium" SOC.



Hydraulic Hybrid Vehicles

The goal is to have the accumulator pressure at the end of the test be similar to the

accumulator pressure at the start of the test so as to ensure meeting the stated tolerance in

Section 4.6 above.  To accomplish this, operate the vehicle over a cycle identical to the

test driving cycle prior to conducting the test. As described above, this vehicle operation

can count toward the requirement for warm-up laps, provided that the test occurs within

the time required from completion of warm up lap.



The hydraulic accumulators can only store about as much energy as is generated over a

typical stop; that energy is  usually less than what is needed to accelerate the vehicle for

the next drive event. Therefore, the pressure in the accumulator is dependant on the last

few hills  of the drive cycle and is usually at a fairly consistent value at the end of any

drive cycle. A "hill" is a complete start-stop sequence on the drive cycle.



Hybrid Electric Vehicles with Capacitors

Follow a procedure similar to that described for hydraulic hybrid vehicles.



Preconditioning Hybrid Vehicles with Electromechanical Flywheels

Follow a procedure similar to that described for hydraulic hybrid vehicles.



12.6  Hybrid Vehicles - Procedures for Determining State of

Charge (SOC) and Net Energy Change (NEC)

The objective of this protocol is to quantify the fuel efficiency of a vehicle, relative to the

fuel that is consumed.  There is to be no net energy provided from the RESS. Thus, the

net energy change (NEC) during a valid test run must be zero, or within a small tolerance

of zero, as defined below.25



In general, the approach to follow, per SAE J2711  §4.3, is to measure the State of Charge

(SOC) at the  beginning of the drive cycle/test run, measure the SOC at the end, and

calculate  the Net Energy Change as SOCfmai minus  SOCmitiai- The NEC is  compared to

the Total  Cycle Energy (TCE) where TCE is defined as the total fuel energy  (TFE) of the

fuel consumed  during the  test cycle (in consistent units) minus the NEC.  The  sign

convention  for NEC is that negative means that  energy  was extracted from the RESS

during the test. In that case, the TCE will be larger than the TFE when NEC is negative.

The NEC is calculated as a percentage of the TCE to determine if a test run is valid, can

be made valid with SOC corrections, or is invalid.  Follow the procedure outlined in  SAE

J1711, §4.3.1.4, with the exception that the selected drive cycle will be used in place of

the HDDS that is cited. More than one drive  cycle may be needed to achieve a  long

enough test run to achieve the NEC "window", as explained in Section 4.6.

The criteria for the absolute value of the NEC/TCE ratio are as follows:

   <1% means the test run is valid and can be used without correction;

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  >1% and <5% means that the test run values for emissions and fuel consumption must

have a SOC correction applied to them; and,

  >5% means that the test run is invalid.

Achieving runs that fall within this "5-percent window" is a matter of some trial and

error.  Preconditioning of the vehicles will be required, as discussed in Section xx. The

drive cycle may  be  repeated to make a longer test run,  if that is advantageous to

achieving the "5-percent window."



Specific procedures for each type of RESS are described in the following sections.



12.6.1 Batteries

The SOC of the battery in a  charge-sustaining hybrid electric vehicle can theoretically be

determined by measuring the amp-hours stored, but in practice it is difficult to do with

sufficient accuracy.  Thus,  for batteries the NEC must be determined indirectly.   The

approach is to measure continuously (using a totalizing ammeter) the flow of current into

and out of the battery. The  integrated (totalized) value, with the appropriate conversion

factors applied, is the NEC.  The specific methodology is shown in SAE J2711, §4.2.1.

Equations  1 and 2. Absolute measures of initial and final SOC will not be available for

the battery; only the net change in stored energy (totalized amp-hours) can be measured.

The  correct sign  convention must be followed:  a negative NEC  means a net loss of

charge from the battery.



12.6.2 Capacitors

The  SOC for capacitors can be determined with acceptable accuracy by measuring the

voltage across the capacitor pack.  Thus the NEC for a test cycle can be readily calculated

by difference of the final and starting SOC.  The specific methodology is described in

SAE J2711, §4.2.2, Equation 3.



12.6.3 Electromechanical Flywheels

The SOC for electromechanical flywheels can be determined with acceptable accuracy by

measuring the inertia and speed of the flywheel (revolutions per minute). Thus the NEC

for a test cycle can be readily calculated by difference of the final and starting SOC.  The

specific methodology is described in SAE J271 1, §4.2.3, Equation 4.



12.6.4 Hydraulic Accumulators

The  SOC  for hydraulic  accumulators can be determined with acceptable accuracy by

measuring the accumulator pressure (pounds per square inch [psi]).  For an accumulator

the SOC can be determined using Equation 1 .

                   -  P*144*FC* —

SOC= - - '-                              (1)

                      (l-k)

where:

   SOC = State of Charge of the accumulator (Ib-ft)

      PC =   pre-charge pressure of the accumulator (psi)

                                                                             42

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       Vc =  volume of gas in the accumulator at pre-charge (ft3)

       P =    current accumulator pressure (psi)

       k =    ratio of specific heats for the pre-charge gas (1.8 for nitrogen at the high

             pressures typical of hydraulic accumulators26).



To convert the units of SOC from Ib-ft to joules, multiply by 1.3558.

The NEC is calculated as the difference in the ending SOC and starting SOC, following a

procedure analogous to  that of capacitors and electromechanical flywheels described

above.



12.6.5 SOC Correction and Net Energy Charge

The SOC correction follows the procedure described in SAE J2711, §4.4 that cites a 2000

                        T7

SAE paper  by Clark, et al.   A separated SOC correction  calculation must be made for

each measured pollutant (if applicable) and for fuel consumption.  The measured values

from at least 3 replicate runs are plotted as a function of NEC.  A linear regression line is

drawn through the data. If the coefficient of determination, R2, is equal to or greater than

0.80, then the data are acceptable for SOC correction.



Using the regression equation, each y-value (i.e., each individual pollutant emission rate

or the fuel consumption value) is calculated for  an x-value (NEC) of zero.  These

calculated numbers are the SOC-corrected values that are then used  for the comparison

calculations in Section xx.

12.7  Fuel Analysis

A supply of test fuel sufficient to complete the test must be procured and fuel parameters

including fuel density analyzed prior to the  start of the test.  The test fuel should be

sequestered once it is procured and analyzed.  If it is necessary to add additional fuel to

the test fuel supply during the course of the test, another fuel analysis must be conducted

to ensure the  test fuel still meets the required fuel parameters.  For each test segment, a

record must be kept of the fuel parameters of the test fuel, including density.



The test fuel  shall  meet fuel specifications summarized in the section of this document

entitled "Test Fuel."



13.  Test Procedure

Refer to Figure 11  for an overview of the steps in the overall conduct of the testing, for

either a track or a chassis dynamometer test.



13.1  General Requirements



Driver Conduct

Drivers must be skilled in test driving.  Drivers shall be in compliance with existing state

and federal laws governing driver licensing.  Generally speaking, a commercial motor

vehicle driver's license or CDL is required in the United States to  operate any type of

                                                                             43

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vehicle with a weight over 26,000 pounds GVWR, including (but not limited to) tow

trucks, tractor trailers and buses. However, these requirements may not apply in all states

and/or on  non-public roadways (e.g., a privately-owned test  track facility.)  It is

recommended that the test facility ensure that all drivers comply  with existing state and

federal laws.  Pre-determined driving procedures  (e.g., gear shifting) shall be specified

prior to the test. Reference SAE J1321 §§5.2 and 5.5.  Drivers shall learn the drive cycle

thoroughly prior to the test, and drive test vehicles precisely according to the drive cycle

in terms of required speed at a given time.



Practice runs of the driving cycle are encouraged, to permit driving cycle adjustments and

to allow drivers to learn the drive cycle, so they can meet the speed-time trace accuracy

requirements.  Gear-shifting representative of real-world driving shall  be encouraged

(neither too smooth nor too aggressive).



For track tests, an observer shall ride in the vehicle with the driver. The observer, using a

stop watch, will coach the driver to meet the target times for each marker, and for the test

overall.  The observer will record the actual time to each marker, in accordance with SAE

J1321. Reference SAE J1321  §6.5, and Fuel efficiency Test Forms 2-3 and 2-4.



The same driver (and observer, if applicable) must stay with each vehicle for the duration

of the test.



Track and Chassis Dynamometer Preparation

If the chassis dynamometer has not been used in over two hours prior to the test, it shall

be necessary to warm up the chassis dynamometer for at least 15 minutes prior to the test.

The test vehicle shall not be used for this warm-up. The track shall be prepared for the

specific drive cycle being used by setting up cones, markers, stop signs, and any other

aids to achieve a consistent, repeatable test run. Creating a repeatable test run will be an

iterative process, requiring multiple trial runs.



Fuel Consumption Measurement Equipment Preparation

Follow general specifications for the fuel measurement method selected. For PEMS, use

40 CFR Part 1065, Subparts C and J.  For gravimetric/portable fuel tank, use SAE J1321

§§5.7.1 and 5.7.3. For laboratory emissions equipment, use 40 CFR Part 86.315-79.



Section  8 of this document provides more details on each of these  fuel measurement

methods.



Additional Steps Required for Hybrid Vehicles

If the vehicle is a hybrid, the RESS SOC should be measured at the start and stop of each

test run.  For each different test cycle a minimum of three test runs must be performed to

provide sufficient data for  a SOC correction,  if needed.  It  is also recommended that at

least one test run have a net positive and  another a net negative  NEC value so that net

SOC calculations  are based on interpolation and not extrapolation. The NEC must meet

the  requirements given in SAE J2711 and vary according to the RESS used.

                                                                              44

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Test Timing



Only "hot start" tests will be used in data reporting and/or data analysis. A hot start is a

test that starts between 10 and 30 minutes of "hot soak" time following a previous test

cycle or preconditioning cycle.



Engine Starting and Restarting

Follow general  specifications for starting the vehicle as described in 40 CFR §86.1236-

85.



Drive Trace Accuracy

The test vehicle must be driven according to the drive cycle in terms of required speed at

a given time as closely as possible, to ensure a reproducible test result. The criteria for

determining whether the vehicle met the  drive cycle differ for each test method, as

described below. EPA requests comments about whether these accuracy requirements ar

reasonable or necessary.



 Track Test Drive Trace Accuracy

The requirements for drive  trace accuracy for a track test are adapted  from 40 CFR

86.115-78. A test run is considered valid if the driven values fall within the drive cycle

(the "commanded" values) according to the  following speed tolerances:

    •  The upper limit is 2 mph higher than the highest point on the drive cycle, within 1

      second of the given time.

    •  The lower limit is 2 mph lower than  the lowest point on the drive cycle, within 1

      second of the given time.



Speed variations greater than the tolerances (such as may  occur during gear changes or

braking  spikes)  are acceptable, provided  they occur for less  than 2 seconds  on any

occasion and are clearly documented as to  the time and speed at that point of the drive

cycle.



Additionally, to be valid, the total  test run shall  fall within  the ±0.5  percent time

requirement as specified in SAE J1321 §8.5.



Chassis Dynamometer Test Drive Trace Accuracy

The requirements for  drive trace accuracy for a chassis dynamometer test are adapted

from  SAE  J2711,  §7.10 using  a  regression  analysis  of the "driven" versus the

"commanded" speed at each  time point. A  test run is considered valid if the slope of the

regression line  is between 0.90 and  1.10,  and the  R-squared value is 0.80 or greater.

Tests that fail to meet this requirement will be deemed invalid.



Running tests in accordance  with the light  duty vehicle certification procedures in CFR

Part 86 Subpart B also would be considered valid tests.

                                                                              45

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13.2  Test Procedure for Test Track

Figure 11 below is a general outline of the test sequence for a test conducted on a test

track.

Figure 11. Generic Test Sequence Using Test Track

  Conventional and Hybrid Vehicle

           Preparation

      (pretest measurements,

   performance tests, calibrations,

          fuel, tires, etc.)

              I

 Test Track Preparation (cones, stop

           signs, etc.)

       c

Start

          Practice drives

               I

    Warm-up both test Vehicles

  Precondition RESS (hybrid only)

       20 - 30 minute (max.)

             Hot soak

               I

            Test Runs

  (One or more drive cycles per run)

                     Repeat, as necessary

                    (perTest/QA plan, etc.)

                       to achieve DQO

       C

End

Steps to Conduct a Track Test

This test protocol incorporates the test procedure elements outlined in SAE J1321  §§6.1

through 6.9, 6.11, and 6.12.  The referenced sections cover details for conducting a test,

which consist of:

                                                                              46

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        Warm up                              reference

        Ambient condition recording             reference

        Start of test                            reference

        Initial test run                          reference

        Test run recording and coaching          reference

        End of test run                         reference

        Interval between test runs                reference

        Test run repeats                        reference

        One test vehicle, different configurations   reference

        Two complete test vehicles              reference

SAEJ1321 §6.1,

SAEJ1321 §6.2,

SAEJ1321 §6.3,

SAEJ1321 §6.4,

SAEJ1321 §§6.5 and 6.6,

SAEJ1321 §6.7,

SAEJ1321 §6.8,

SAEJ1321 §6.9,

SAEJ1321 §6.11,

SAEJ1321 §6.12.

For §6.8 and 8.13; substitute  the phrase "checking  data from PEMS" for the word

"refueling" if using the PEMS/carbon balance method instead of the gravimetric method.



13.3 Test Procedure for Chassis Dynamometer

Figure 12 below is a general outline of the test sequence for a test conducted on a chassis

dynamometer.

                                                                          47

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Figure 12. Generic Test Sequence Using Chassis Dynamometer

    Vehicle Preparation (pretest

 measurements, performance tests,

    calibrations, fuel, tires, etc.)

              Start

  Practice following drive cycle on

          dynamometer

  Precondition RESS (hybrid only)

       20 - 30 minute (max.)

            Hot soak

            Test Runs

  (One or more drive cycles per run)

                                  Repeat, as necessary

                                  (per test/QA plan, etc.)

                                     to achieve DQO

       c

End

Steps to Conduct a Chassis Dynamometer Test

This test protocol incorporates the test procedure elements outlined in 40 CFR Part 86,

Subpart B.   Although Subpart B is written for light duty certification procedures, the

steps in Subpart B are in principle the  same for performing  heavy  duty  chassis

dynamometer runs.

                                                                              48

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Certain  aspects of  Subpart B shall  be modified for this  test. For  example,  the

dynamometer roll specifications per  86.108-00 will differ for heavy  duty  chassis

dynamometer rolls.



References  in  Subpart B  to  FTP driving  schedules and  provisions  dealing  with

evaporative  emission  testing,  the OBD requirements,  and  the  smoke  emission

requirements do not apply.



13.4 Coastdown Test Procedure to Calculate Road Load

When conducting a fuel efficiency test using a chassis dynamometer, coast down testing

needs to be  conducted to supply road load inputs to the chassis dynamometer.  The

vehicle must be tested at its test weight  including the payload specified for that drive

cycle.



Depending upon the  type of chassis dynamometer used, the appropriate choice of SAE

coast down test shall be conducted:  SAE  J1263, SAE J2263, or SAE J2264.28 Refer to

these  coastdown  procedures  for  details. For  example, if a single  roll electric

dynamometer is used, J2264 is the appropriate coastdown procedure.

                                                                           49

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14  Required Number of Test Runs



Multiple tests will be needed to establish whether a vehicle meets the performance

standard for a SmartWay designation, as test to test variability (precision) will affect the

results of any single test. We expect that precision will be lower for a track test than for

the dynamometer tests, but in both cases, statistical data will be developed to compute the

required number of tests to provide confidence that the vehicle meets the performance-

based designation.   The criterion for meeting this designation is an 80 percent probability

that the test results exceed the fuel efficiency designation by an amount equal to the

lower tail of the 95 percent confidence interval of the test measurements.  For example, if

the performance based designation of a particular type of truck was 7.5 miles per gallon,

and replicate measurements showed that the 95 percent confidence interval for the test

was 0.05 miles per gallon, then the results of the statistical computation described below

and in Appendix I should provide evidence of an 80 percent probability that the test result

was 7.5 mile per gallon or greater.



The specific values underlying the statistical assumptions and statistical farmulae are

different will be slightly different for track and dynamomter test data, and these are

presented below and in Appendix I. [A note to rqeaders: We invite comment on this

method.] It is important to note that the following statistical techniques are relevant to

conducting the testing against a known environmental reference truck (discussed in

Purpose and Scope section on page 6 of this document). Testing against an

environmental reference can minimize the number of tests needed to produce appropriate

confidence in the test results.



14.1  General Requirements

The number of tests required for fuel efficiency and emission testing is determined from

the following criteria:



1.  A minimum of three (3) tests are required to provide the basic result of a mean

emission reduction and 95 percent confidence interval on  that mean based  on measured

variability for each of the measurements and test parameters.

2. Additional tests  may be required to meet the requirement that the vehicle meets the

performance criterion.   These criteria become  controlling for low carbon emission/fuel

consumption reductions and/or high test  variability. The procedure to determine the

appropriate number  of tests is given in the following sections, with additional information

in Appendix I

3. Additional tests may be desired by the applicant to reduce the width of the 95 percent

confidence interval on the mean carbon emission/fuel consumption reduction.  Appendix

I provides additional explanation and  example scenarios.  This  third criterion is a

consequence of applying  standard  statistical procedures to the test design and data

analysis. At fixed measurement variability, normal statistical procedures lead to a small

number of tests giving a broader 95 percent confidence interval than a larger number of

tests.    To  any potential  technology user,  a  reported reduction in  emissions/fuel

consumption of 40 percent ± 5 percent is better than a reported value of 40 percent ± 20

percent, and will be  given more credence.

                                                                               50

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Confidence Interval on the Result

A consequence of the unavoidable variability in test measurements is that the mean of a

small number of measurements has a small probability of giving the true fuel

consumption/emission reduction. In some cases it may not be possible to make a

statistically-significant determination that the measured reduction is different from zero.

The results of measurements conducted using this protocol will be presented as the mean

and 95% confidence interval on that mean, calculated using the sample standard

deviations determined from the test data. Because sample standard deviations are

available, the t-statistic is applied to compute the confidence intervals (as opposed to the

"z" statistic that was used for the sample size calculation).



14.2  Number of Test Runs for Test Track Test

This protocol requires that sufficient tests be conducted to have an 80 percent probability

of detecting whether the fuel efficiency meets or exceeds the performance standard,

computed from the expected experimental variability for the various  measurements.  In

this context, "detecting" means that the  performance standard is less than or equal to the

lower tail of the 95 percent confidence interval. Insufficient replication can result in

inability to detect a statistically significant fuel consumption benefit.



A sample-size  equation was derived to explicitly compute the number of tests required

for normally distributed measurements having known standard deviations. However,

since the actual testing procedure will be based on sample standard deviations and t-

statistics, a correction factor was applied to the sample-size equation to account for the

extra variation in the t-distribution relative to that of the normal distribution.  Some

results  of applying that calculation are presented in Table 1 for emission reductions and

fuel efficiency increases.  Equations used to compute the number of tests required are

presented in Appendix I.



Table xx presents the variability of emissions (in this example, NOx), and fuel efficiency

measurements  based on standard deviations calculated from an analysis of actual test

track data of Kenworth truck tractors driving a suburban drive cycle.29 The results in

Table 1 are based on the sample-size equation with the correction factor for the one-tailed

t-distribution.  More tests than are shown in Table 1 may be required under conditions of

higher  variability.



The column headings in the first row of the table give the assumption that the hybrid

vehicle will show an emission reduction or a fuel  efficiency improvement of 5 percent,

20 percent, 50  percent, or 85 percent from the baseline conventional emission/fuel

efficiency levels. In developing the Test/QA plan, selection of this value will be based

on the  applicant's experience and expectation. The second row gives the constant and

known baseline conventional vehicle variability.  The third row is the assumed

measurement variability for the hybrid vehicle based on the variability of the

conventional vehicle. (Variability is expressed as the known standard deviation at the

emission/fuel efficiency level divided by the corresponding conventional vehicle mean

emission/fuel efficiency level and multiplied by 100 percent.)  The fourth row gives  the

                                                                               51

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calculated number of tests required to have 80 percent probability that the 95 percent

confidence interval about the mean expected emission reduction or fuel efficiency

improvement would not include zero.



 Table x.  Number of replicate test track tests (for both conventional and hybrid vehicle)

            to achieve an 80 percent probability of detecting emission reductions and fuel

            efficiency improvements at a confidence level of 95 percent

Expected emission reduction or fuel efficiency

improvement

Variability for baseline conventional vehicle NOX

measurement13

Variability for hybrid vehicle NOX measurement

(assumed to be same as for conventional vehicle)

Number of tests required to have 80 percent probability

of detecting expected NOx emission reduction11

Variability for baseline conventional vehicle fuel

efficiency measurement (MPG)b

Variability for hybrid vehicle fuel efficiency

measurement (MPG) (assumed to be same as for

baseline conventional vehicle)

Number of tests required to have 80 percent probability

of detecting expected fuel efficiency improvement21

5%

2.58%

2.58%

5

2.46%

2.46%

5

20%

2.58%

2.58%

2

2.46%

2.46%

2

50%

2.58%

2.58%

2

2.46%

2.46%

2

85%

2.58%

2.58%

2

2.46%

2.46%

2

       Computed under the assumption of normally distributed measurements having known variability.

       Additional tests may be required if sample standard deviations obtained during testing are higher.

       Computed from standard deviation values from actual track testing of diesel trucks. Citation:	

The fifth through the seventh rows (shaded) repeat the calculation for the fuel efficiency

measurement.  Table 1 shows that, for both NOX and fuel efficiency, six tests are

sufficient to distinguish between zero and emission reductions/fuel  efficiency

improvements as low as 5 percent, based on the assumption that the variability values in

Table x represent the true variability values.  Two tests would be sufficient to detect the

other emission reductions/fuel efficiency improvements, but three are required by this

protocol to provide a measured standard deviation.

14.3  Number of Test Runs for Chassis Dynamometer Test

This protocol requires that sufficient tests be conducted to have a high probability of

detecting the emission reductions/fuel efficiency improvements expected by the

applicant. This requirement was implemented to ensure, as much as was practical, that

the test program will accomplish the applicant's goals. This requirement will generally

                                                                              52

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only be important to testing intended to measure low emission reductions/fuel efficiency

improvements and/or measurements having high variability.



Specifically, the test program is to be designed such that there is an 80% probability of

detecting the emission reductions/fuel efficiency improvements expected by the

applicant, computed from the expected experimental variability for the various

measurements. In this context, "detecting" means that the 95% confidence interval does

not include zero emissions reduction or zero fuel efficiency improvement. Insufficient

replication can result in inability to detect a statistically  significant benefit of a change in

fuel consumption, as illustrated below with a specific example of a hybrid technology.



A sample-size equation was derived to explicitly compute the number of tests required

for normally distributed measurements having known standard deviations.  However,

since the actual testing procedure will be based on sample standard deviations and t-

statistics, a correction factor was applied to the sample-size equation to account for the

extra variation in the t-distribution relative to that of the normal distribution.  Some

results of applying that calculation are presented in  Table 2 for particulate matter (PM)

and NOX emission reductions.  The equation used to compute the number of tests required

is presented in Appendix C.



In Table 2 the baseline conventional vehicle is assumed to be operating at a fixed

emission value for PM (top half of table) and NOx (bottom three rows).  PM and NOX

measurements are used in Table 2 because dynamometer laboratory-based measurement

standard deviations were known from previous work. The results in Table 2 are based on

the sample-size equation with the correction factor for the t-distribution.  More tests than

shown in Table 2 may be required under conditions of higher variability, and careful

examination of the number of tests needed will be required during test/QA plan

development.



The column headings in the first row of the PM and NOX sections  of the table give the

assumption that the hybrid vehicle will show emissions reductions of 5%, 20%, 50%, or

85% from the baseline conventional vehicle emissions levels. In developing the Test/QA

plan, selection of this value will be based on the applicant's experience and expectation.

The second row gives the constant and known baseline conventional vehicle variability.

The third row is the assumed measurement variability for the hybrid vehicle based on the

variability of the conventional vehicle. (Variability is expressed as the known standard

deviation at the emission level divided by the corresponding conventional vehicle mean

emission and multiplied by 100%.)  The fourth row gives the calculated number of tests

required to have 80% probability  that the 95% confidence interval about the mean

expected emission reduction would not include zero.



 Table xx. Number of replicate chassis dynamometer tests (for both conventional and

            hybrid vehicle) to achieve an 80% probability of detecting emission

            reductions at a confidence level of 95%

                                                                              53

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Expected emission reduction (relative to the respective

1990 certification levels for PM and NOX, respectively )

Variability of baseline conventional vehicle PM

measurement0

Variability of hybrid vehicle PM measurement

(assumed to be the same as for conventional vehicle)

Number of tests required to have 80% probability of

detecting expected PM emission reductiona

Variability for conventional vehicle NOX measurement

at 1990 levels0

Variability of hybrid vehicle NOX measurement

(assumed to be the same as for conventional vehicle)

Number of tests required to have 80% probability of

detecting expected NOx emission reduction11

5%



2%



2%



4



2%



2%



4



20%



2%



2%



2



2%



2%



2



50%



2%



3%



2



2%



7%



2



85%



2%



10%



2



2%



NAb



NAb



       Computed under the assumption of normally distributed measurements having known variability.

       Additional tests may be required if sample standard deviations obtained during testing are higher.

b      NA = Not Available.

0      Variability of emission measurements from a chassis dynamometer is assumed to be the same as

       historical data from an engine dynamometer laboratory running a baseline uncontrolled engine and

       the same engine with add-on emission control technologies offering varying levels of control.



The fifth through the seventh rows (shaded) repeat the calculation for the NOX

measurement. No estimate of variability was available for the NOX measurement at an

85% reduction. Table xx  shows that, for both PM and NOX, five tests are sufficient to

distinguish between zero  and emissions reductions as low as 5%, based on the

assumption that the variability values in Table 2 represent the true variability values.

Two tests would be sufficient to detect the other emissions reductions, but three are

required by this protocol to provide  a measured standard deviation.

15 Fuel Efficiency Calculation



FUEL CONSUMPTION - GRAVIMETRIC

At the conclusion of a test lap, the portable fuel tank is detached and weighed.  The mass

of fuel consumed is the difference between the pre-test and post-test mass of the fuel tank

and fuel.   The volume of fuel  is  calculated by  dividing the mass consumed by the

measured density of the fuel:

V = m/p

Where V is the volume of fuel consumed during the test lap

       M is the mass of fuel consumed during the test lap, and

       P is the density of fuel as measured using ASTM method D-1298

                                                                                 54

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For calculation of fuel efficiency from gravimetric data conversion factors are involved,

as the data are in mass units, but fuel efficiency is expressed in volumetric units (mi/gal

or k/L).   SAE J1321,  §A.3  describes the method of calculation and supplies the

conversion factors.



FUEL CONSUMPTION- CARBON-BALANCE

Fuel consumption can be measured by the carbon balance method, using data from the

exhaust gas analysis as described in SAE standard J1094a.  This method calculates fuel

consumption from measured emissions of carbon-bearing gases. The  calculations require

input of the emission rates (in grams/mile) of the  total hydrocarbons (THC), carbon

monoxide (CO), and carbon dioxide (CO2).



These emissions can be measured using a conventional laboratory test cell or a portable

emissions monitoring system (PEMS).  The laboratory test cell can only  be used to

measure emissions of vehicles tested on a chassis dynamometer, whereas the PEMS can

be used to  measure emissions of both dynamometer and track  tests.  The method of

calculation of fuel efficiency from emissions data shall be consistent with the procedure

described for automobiles in 40 CFR 600.113-93.



DISTANCE DRIVEN

Distance  driven may be determined either by use of the vehicle odomometer, or by the

use of global positioning system (GPS) data. The use of GPS data would be applicable

only to track tests.



MASS-DISTANCE SPECIFIC METRICS



In some  circumstances it might be appropriate to report the results in mass-distance

specific form, that is in a metric  such as ton-miles per gallon. In most cases, this is not

necessary because the test payload is standardized, which means that the payload mass

remains a constant percentage of the maximum payload.  However, if a truck is designed

to improve fuel efficiency through reduction of weight, it is possible that the maximum

payload will increase and  thus the test payload,  expressed as a percent of maximum

payload would also increase. In  such a case, it would be informative to have the metric

reflect  this increased  efficiency.  Reporting   of a a mass-distance  specific metric,

however, should be accompanied with all relevant information about paloads and percent

of maximum payload.



16 Reporting and  Documentation

This section describes the  procedures for reporting  data, including  what data must be

included and what format should be used.



16.1  Reports

The test report will contain the following topics:

    1.  Introduction;

                                                                            55

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   2.  Description and identification of vehicle tested. Refer to SAE J2711 §6.2 and

       SAE J1321  Type II Test Data Form 1;

   3.  Procedures and methods used in testing. Refer to SAE J1321 Type II Test Data

       Forms 2-2 and 2-4;

   4.  Statement of operating range over which the test was conducted;

   5.  Discussion of results including:

          a.  Explanation and documentation of necessary deviations from the protocol,

             and

          b.  Discussion of QA issues;

   6.  References; and

   7.  Appendices:

          a.  QA/QC activities and results,

          b.  Raw test data, and

          c.  Equipment calibration results.

16.2  Data and Metrics



The primary data collected is units of fuel consumption over units of time, distance, or

power.  The mean of the test replicates and confidence limits shall be presented.  The

carbon balance measurement method provides a methodology to convert carbon mass to

fuel consumed.



Metrics may include a fuel consumption rate per distance (gallons per mile) and/or per

time (gallons per hour)  The fuel consumption per time metric accommodates vocational

trucks that consume fuel while conducting non-tractive mission work (operating a refuse

truck side arm and compacting trash; operating a utility aerial lift and supplying power to

the grid).  This metric may be weighted into the fuel consumed per distance metric for

convenience and  ease of comparison, using  an  appropriate weighting  for that  vehicle

application, which would be  described in the "drive cycle." For over-the-road freight

truck applications like highway line haul and regional haul, a gallon per ton-mile metric,

as decribed  in the  previous  section, "mass-distance  specific metrics," may be most

reasonable, since  the main function of these vehicles  is to carry tonnage.  This  metric

could be readily  calculated using the test results of  fuel consumption,  distance, and

payload factors in the drive cycle.



If a testing organization wishes to collect emissions data other than carbon, this data shall

be reported as emission rates in grams/kilowatt-hour (g/kW-h) [grams/brake horsepower-

hour (g/bhp-hr)], grams/mile (g/mi) [grams/kilometer (g/km)] or as grams per cycle,

depending on the  test method (track or chassis) and the user's decision as to which is the

most appropriate.



16.3 Quality  Assurance and Control

Quality assurance and quality control procedures are used to ensure the accuracy and

precision of test results. Accuracy of fuel consumption measurements is primarily

dependent on the accuracy of the following measurements:

                                                                              56

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   •   For fuel consumption measured by carbon-balance method:

          o   Accuracy of gas analyses for CO2, CO and HC

          o   Accuracy of exhaust flow determination

          o   Accuracy of fuel carbon and density

   •   For fuel consumption measured by gravimetric method:

          o   Accuracy of scales used to weigh fuel

          o   Accuracy of measurements of fuel density and temperature correction

   •   For tests conducted on a dynamometer

          o   Accuracy of dynamometer force simulation

          o   Accuracy of estimates of road load and aerodynamic drag

          o   Accuracy of speed and distance measurements

   •   For tests conducted on a test track

          o   Accuracy of speed measurements

          o   Accuracy of distance measurements



Accuracy of these measurements is primarily documented by the use of calibration of the

instruments and other measuring devices against known standards.  The specific

calibration details for the measurements needed are given in the appropriate test

descriptions, including SAE and ASTM test method documentation of the relevant parts

of the Code of Federal Regulations.



In addition to such documentation, the accuracy of the fuel efficiency metric ccan be

directly tested by comparison of standardized reference trucks, for which the fuel

efficiency has been tested multiple times by multiple laboratories.



The short-term precision of a fuel efficiency test method is estimated by use of replicate

tests.  The acceptable level of precision is determined by the final user of the test results,

and sufficient replicate measurements should be taken to ensure that the acceptable level

of precision can be documented.



Quality assurance activities should be documented by the following:

   •   Standard Operating Procedures to ensure that test procedures are done properly

   •   Records of instrument calibrations

   •   Records of replicate tests and calculations of precision estimates

   •   Records of calculations of fuel efficiency

   •   Daily  test log that documents all testing activities, including anomalous behavior

       and events that could affect test results.

16.4  Assessment

Each  testing organization should  conduct an internal assessment of  its quality and

technical systems  and should  allow  external assessments of these systems  by QA

personnel.   After an  assessment,  the  testing organization  will  be  responsible  for

developing and implementing corrective actions in response to the assessment's findings.

                                                                              57

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As appropriate, an organization with oversight responsibilities may conduct assessments

to determine the testing organization's  compliance with its test/QA plan. Examples of

assessments  are  described in EPA's ETV QMP.30  It is  highly recommended  that

assessments be conducted with a rigor comparable to those described in EPA's Guidance

on Technical Audits and Related Assessment for Environmental Data Operations 31 and

Guidance on Assessing Quality Systems32

17 Appendices

                                                                            58

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17.1 Appendix A



Abbreviations and Acronyms

ACEEE      American Council for an Energy Efficient Economy

bhp          brake horsepower

Btu          British thermal unit

CARB       California Air Resources Board

CBI          confidential business information

cfm          cubic feet per minute

CFR         Code of Federal Regulations

CO          carbon monoxide

CO2          carbon dioxide

cu. yd.       cubic yard

DQO         data quality objective

EPA         Environmental Protection Agency

EPAct 2005   Energy Policy Act of 2005

ETV         Environmental Technology Verification Program

ft            feet

FTA         Federal Transit Administration

FTP          federal test procedure

gal           gallon

g/mi          grams per mile

g/bhp-hr      grams per brake horsepower-hour

g/kWh       grams per kilowatt-hour

GVWR      gross vehicle weight rating

WC ratio     Hybrid Vehicle Fuel Used/Comparable Baseline Vehicle Fuel Used

HAP         hazardous air pollutant

HDHV       heavy duty  hybrid vehicle

hp           horsepower

HVAC       heating, ventilation, and air conditioning

in            inches

IRS          Internal Revenue Service

km           kilometer

L            liter

Ib            pound

mph          miles per hour

NEC         net energy change

NO          nitric oxide

NO2          nitrogen dioxide

NOx         nitrogen oxides

NREL       National Renewable Energy Laboratory

NYCT       New York City Transit

OBD         on-board diagnostics

ORD         Office of Research and Development

OTAQ       Office of Transportation and Air Quality

                                                                          59

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PEMS       portable emissions monitoring system

PM          particulate matter

[Reserved]

                                                                               60

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17.2-17.8 Appendices B - H

[Reserved]

                                                  61

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17.9  Appendix I





Statistics - Test Track Testing



Example Sample Size Calculation for Emission Reduction

This appendix presents sample calculations for determining the minimum number of tests

required to detect a significant emissions or fuel consumption reduction.  The calculation

is based on:



1)   The emissions variability is taken to be known for the population of measurements;

2)   A known baseline conventional vehicle mean emission;

3)   A mean hybrid vehicle emission (the product of the conventional vehicle emission

     and the expected emissions reduction); and

4)   One part of the equation is based on the assumption of known standard deviations

     and the normal distribution.  However, since the actual testing procedure is based

     on sample standard deviations and t-statistics, a correction factor is added to the

     sample-size equation to account for the extra variation in the t-distribution relative

     to that of the normal distribution.

The criterion being used is that the minimum number of tests required for use of this

protocol is the number of tests required to have an 80% probability of detecting the

specified emission reduction at the 95% confidence level. The basic equation being used

for the calculation is:



where:

   n      =  sample size in each group, rounded up to the next integer;

    za    =  normal distribution value corresponding to upper-tail probability of a ;

             and

    zp    =  normal distribution value corresponding to upper-tail probability of ft.

    I -a  =  confidence coefficient on comparison of means (0.95 minimum);

    I-/?  =  probability of detection of reduction/increase (0.80 minimum);

    cr^    =  squared standard deviation of conventional vehicle emission data,

             expressed as a percent of the conventional vehicle emission value;

    <J2H    =  squared standard deviation of hybrid vehicle emission data, expressed as a

             percent of the conventional vehicle emission value;

   6      =  difference between conventional and hybrid vehicle emissions mean,

             expressed as a percent of the conventional vehicle emission value.

                                                                             62

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Note that o2c ,  a2H , and S are expressed as percentages of the conventional vehicle

emission.  This transformation was used to simplify the equation and allow its use for

Table 1 in Section 5.3.1. For Table 1, the baseline conventional vehicle mean emission

value was 12.495 grams/mile, taken from the suburban drive cycle of the Kenworth data.1

The parameter V is tabulated under different names in statistics reference texts.  It is the

V value corresponding to 'the tail area of the unit normal distribution' in Box, Hunter,

and Hunter (1978).  In the Standard Mathematical Tables (CRC, 1968), V is known as

'x', and the tail area is labeled ' 1 - F(x)\ where F(x) is the cumulative distribution

function of a standardized normal random variable. To obtain the value of V from the

statistical tables, a (or /?) is the probability (ranging from 0.5000 to 0.0000) in the body of

the table, and V is read (or interpolated) from the appropriate column and/or row,

ranging from 0.00 to 4.00 over that range. The value V can be calculated within an

EXCEL® or QUATTRO PRO® spreadsheet as the absolute value of the function

returning the inverse of the standard normal cumulative distribution,

NORMSINV(probability), by setting probability equal to a or/?, as appropriate.  A

derivation of the correction factor, z2a/2, is available in Appendix A of the EPA G-4

guidance document (Guidance on the Data Quality Objectives Process (EPA/600/R-

96/055)).



Table C-l gives a step-by-step calculation example drawn from Table 1 for an 80%

probability (fi = 0.20) of detecting a 5% and a 50% emission reduction at the 95%

confidence level (a = 0.05).

             _Proper citation is needed, here, for the Kenworth truck testing dataset.





                                                                               63

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 Table C-l.   Example calculation of minimum number of replicate test track tests

               required to achieve an 80% probability of detecting emission reductions

               at a confidence level of 95%.



Emission reduction relative to conventional vehicle emission, S, %

Known measurement variability for conventional vehicle, ac , %

Known measurement variability for hybrid vehicle, aH , %

a

Za

ft

Zfi

\<j2H+(j2c(l-5llW}2^\/52

(za+zp)2[a2H+a2(l-S/WO)2]/S2

4/2

(Za+Zp)2[a2H+a2(l-S/WO)2]/S2+z2a/2

Number of tests required , n

Table 1,

Col.l

5

2.58

2.58

0.05

1.645

0.20

0.842

0.514

3.18

1.35

4.53

5

Table 1,

Col. 3

50

2.58

2.58

0.05

1.645

0.20

0.842

0.003

0.02

1.35

1.37

2a

Note:      The minimum number of tests is three. If'«' is less than three, '«' equals three.

Example Sample Size Calculation for Fuel efficiency Improvement

This appendix presents example calculations to illustrate calculation of the minimum

number of tests required to detect a significant fuel efficiency improvement.



The calculation is based on:



1)   The fuel efficiency variability is taken to be known for the population of

     measurements;

2)   A known baseline conventional vehicle mean fuel efficiency;

3)   A mean hybrid vehicle fuel efficiency; and

4)   One part of the equation is based on the assumption of known standard deviations

     and the normal distribution. However, since the actual testing procedure is based

                                                                            64

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     on sample standard deviations and t-statistics, a correction factor is added to the

     sample-size equation to account for the extra variation in the t-distribution relative

     to that of the normal distribution.

The criterion being used is that the minimum number of tests required for use of this

protocol is the number of tests required to have an 80% probability of detecting the

specified fuel efficiency increase at the 95% confidence level. The basic equation being

used for the calculation is:

where:

   n     =  sample size in each group, rounded up to the next integer;

    za    =  normal distribution value corresponding to upper-tail probability of a ;

              and

    z p    =  normal distribution value corresponding to upper-tail probability of ft.

    I - a  =  confidence coefficient on comparison of means (0.95 minimum);

    I-/?  =  probability of detection of reduction/increase (0.80 minimum);

    cr^    =  squared standard deviation of conventional vehicle fuel efficiency data,

              expressed as a percent of the conventional vehicle fuel efficiency value;

    a2H    =  squared standard deviation of hybrid vehicle fuel efficiency data,

              expressed as a percent of the conventional vehicle fuel efficiency value;

   S     =  difference between conventional and hybrid vehicle fuel efficiency mean,

              expressed as a percent of the conventional vehicle fuel efficiency value.



Note that a2C , a2H , and 6 are expressed as percentages  of the conventional vehicle fuel

efficiency.  This transformation was used to simplify the equation and allow its use for

Table 1.  The parameter V is tabulated under different names in statistics reference texts.

It is the V value corresponding to 'the tail area of the unit normal distribution' in Box,

Hunter, and Hunter (1978).   In the Standard Mathematical Tables (CRC, 1968), V is

known as 'x', and the tail area is labeled ' 1 - F(x)', where F(x) is the cumulative

distribution function of a standardized normal random  variable. To obtain the value of

V from the statistical tables, a (or/?) is the probability (ranging from 0.5000 to 0.0000)

in the body of the table, and  V is read (or interpolated) from the appropriate column

and/or row, ranging from 0.00 to 4.00 over that range.  The value V can be calculated

within an EXCEL® or QUATTRO PRO® spreadsheet as the absolute value of the

function returning the inverse of the standard normal cumulative distribution,

NORMSINV(probability), by setting probability equal to a or/?, as appropriate. A

derivation of the correction factor, z^/2, is available in Appendix A of the EPA G-4

                                                                                65



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guidance document {Guidance on the Data Quality Objectives Process (EPA/600/R-

96/055)).



Table C-2 gives a step-by-step calculation example drawn from Table 1 for an 80%

probability (ft = 0.20) of detecting a 5% and a 50% fuel efficiency increase at the 95%

confidence level (a = 0.05).





 Table C-2. Example calculation of minimum number of tests.



Fuel efficiency increase relative to conventional vehicle fuel efficiency,

S,%

Known measurement variability for conventional vehicle, ac , %

Known measurement variability for hybrid vehicle, <JH , %

a

Za

ft

Zfi

Tc4+crc(l + £/100)2l/£2

(za+zp)2[al+al(\ + 6l\W)*]/?

z2Jl

(za+Zp)2[vl+rt(l + 5HW}2]/5^+zll2

Number of tests required , n

Table 1,

Col.l

5

2.46

2.46

0.05

1.645

0.20

0.842

0.509

3.15

1.35

4.50

5

Table 1,

Col. 3

50

2.46

2.46

0.05

1.645

0.20

0.842

0.003

0.02

1.35

1.37

2a

Note:

          The minimum number of tests is three. If '«' is less than three, '«' equals three.

Statistics - Chassis Dynamometer Testing



The calculations for the minimum number of tests required to detect a significant

emissions reduction or fuel efficiency increase are identical to those presented in the

preceding section.



Based on the calculations presented in the preceding section, Table D-l gives a step-by-

step calculation example drawn from Table 2 of Section 5.3.2 for an 80% probability (ft =

                                                                             66

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0.20) of detecting a 5% and a 50% emission reduction at the 95% confidence level (a =

0.05).

 Table D-l.    Example calculation of minimum number of replicate chassis

               dynamometer tests to achieve an 80% probability of detecting emissions

               reductions at a confidence limit of 95%.



Emission reduction relative to conventional vehicle emission, S, %

Known measurement variability for conventional vehicle, ac , %

Known measurement variability for hybrid vehicle, <JH , %

a

ZCL

ft

ZP

[<4+^(i-£/ioo)2]/£2

(za+Zp)2[al+a2c(\-5l\W}2]/52

t/2

(za+zp)2[a2H+a2(l-S/WO)2]/S2+z2a/2

Number of tests requireda, n

Table 2,

Col.l

5

2

2

0.05

1.645

0.20

0.842

0.304

1.88

1.35

3.23

4

Table 2,

Col. 3

50

2

3

0.05

1.645

0.20

0.842

0.004

0.02

1.35

1.38

2a

Note:

The minimum number of tests is three.  If'«' is less than three, '«' equals three.

References



CRC. Standard Mathematical Tables, 16th Ed.  S. Shelby, Ed. The Chemical Rubber

   Company, Cleveland, OH. 1968.

Box, G. E. P., W. G. Hunter, and J. S. Hunter. Statistics for Experimenters. John Wiley

   & Sons, New York, NY.  1978.

EXCEL®.  Microsoft Corporation, Redland, WA. 2001.

QUATTRO PRO®.  Corel Corporation, Ottawa, Ontario,  CANADA. 2001.

                                                                           67

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17.10 Appendix J



Calculations to Compare the Hybrid Version of a Heavy Duty

Vehicle to the Non-Hybrid Version

Comparative testing of a hybrid vehicle to its non-hybrid "twin," whether the testing is

conducted on a test track or on a chassis dynamometer, involves multiple tests of a

baseline conventional vehicle and multiple tests of a hybrid vehicle. This section

describes the data analysis procedure that will be used to calculate the emission

reductions and increase in fuel efficiency from these data.



This calculation assumes that the same test method (test track or chassis dynamometer) is

used for all the testing.



Procedure for Calculating Emission Reduction

Let EC and EH refer to the emission rates of a single pollutant for conventional and hybrid

vehicles, respectively. Once the E values for the tests are available, the corresponding

sample means (Ec and EH) and standard deviations (sc and SH) are computed using

Equations 2 and 3.



                            "C                          »H

                            IX,                 _    IX,

                       Ec = —	      and      EH = —	

                              nc

          sc = JS fe - Ec )   (nc ~ 1)   and   SH =  £ (EHJ - EH )   (nH -1)

              V  i            /                   V i            /                  (3)



where:



            Ec = mean emission rate for the conventional vehicle for a single pollutant,

            EH = mean emission rate for the hybrid vehicle for a single pollutant,

            Ecjt = emission rate for a single conventional ith test for a single pollutant,

            EH* = emission rate for a single hybrid ith test for a single pollutant,

      nc and nH = number of conventional and hybrid tests, and

      sc and SH = standard deviations of conventional and hybrid tests.



The raw emission reduction for each pollutant, ERRAW-, is then computed as the difference

between the mean emission rates for the conventional and hybrid cases, divided by the

conventional case mean emission rate, as shown in Equation 4.



                               ERRAW = (EC - EH }/EC                              . .

                                                                           68

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The upper and lower bounds of the approximate confidence interval (CT) around

are computed using Equations 5a and 5b.

            CI (upper bound) = ERRAW+\\ ta/2 • p- + (l-ERRAW)2±-  IE,

                                             V I'JLT               l'f^ I /

                                                                                     (5a)

            CI (lower bound) = ERRAW -

            / C              i V

            I H  , /I   777?   \2 AC

            |- + (l-^_) -

In the equations above, to/2 is the (1 - a/2) percentile of the t-distribution, with degrees of

freedom, u, given by Equation 6 (rounded down)2, and a = 1 - (confidence level /100%).

However, since the testing procedure is interested only in unidirect!onal positive

reductions, one-tailed tests will be conducted.  Consequently, only the lower bound of the

confidence interval will be of interest, and ta will replace ta/2 in Equation 5b.  Thus, in

tables giving distributions oft for two-tailed tests, use 2a to obtain the critical value. For

example, if the confidence level is 95%, then a = 0.05; if in addition, v = 5, then ta =

2.015.

                               ^S2H/nH+(l-ERRAir)2s2c/nc

                u =

The fractional values of emission reduction and the confidence intervals are converted to

percentages by multiplying by 100 percent.



5.2.2.2 Procedure for Calculating Fuel efficiency Improvement

Let FC and FH refer to the fuel efficiency rates in miles per gallon (MPG) for baseline

conventional  and hybrid vehicles, respectively.  Once the F values for the tests are

available, the corresponding sample means (Fc  and FH ) and standard deviations (sc and

SH) are computed using Equations 2 and 3, except that FC and FH values are used instead

of EC and EH  values in the formulas.



The raw fuel  efficiency increase, F!RAW, is then computed as the difference between the

mean fuel efficiency rates for the hybrid and conventional cases, divided by the baseline

conventional  case mean fuel efficiency rate, as shown in Equation 7.

FI    =

1 1RAW

                                             -F

                                               l

                                                                                    (5b)

                                                                                      (6)

                                                                                      (7)

' The value of o rounded down from Equation 9 can generally be approximated as nc + nH - 3.

                                                                               69

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The upper and lower bounds of the approximate confidence interval (CI) around F!RAW

are computed using Equations 8a and 8b.

            CI (upper bound) = FIRAW +\  ta!2

                                                                                     (8a)

             CI (lower bound) = FIRAW -

In the equations above, to/2 is the (1 - a/2) percentile of the t-distribution, with degrees of

freedom, u, given by Equation 9 (rounded down)3, and a = 1 - (confidence level /100%).

However, since the testing procedure is interested only in unidirect!ona\ positive

increases, one-tailed tests will be conducted.  Consequently, only the lower bound of the

confidence interval will be of interest, and ta will replace ta/2 in Equation 5b.  Thus, in

tables giving distributions oft for two-tailed tests, use 2a to obtain the critical value. For

example, if the confidence level is 95%, then a = 0.05; if in addition, v = 5, then ta =

2.015.

                O = -F

The fractional values of emission reduction and the confidence intervals are converted to

percentages by multiplying by 100 percent.

                                                                                     (8b)

                                                                                       (9)

; The value of o rounded down from Equation 9 can generally be approximated as nc + nH - 3.

                                                                                70

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17.11 Appendix K

Drive Cycles: Time-Speed-Distance Data and Summary Statistics

[Reserved]

                                                         71

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18 End notes

1 The primary use of SAE J1321 is to measure the fuel economy impact of various truck

components.  The percent fuel economy improvement approach is well-suited to this

purpose.

2 A hybrid vehicle can generally be defined as a vehicle in which the motive power

comes from two sources: a consumable fuel converter (e.g., internal combustion engine)

and a rechargeable energy storage system (RESS).

3 Line haul and regional combination tractor-trailers use more fuel than all other heavy

duty on-highway vehicles combined, due to high annual mileage, and have significant

potential to save fuel by reducing aerodynamic and rolling drag.  Intermodal drayage

trucks contribute significantly to CC>2 and other emissions in and around marine port

facilities. The remaining heavy duty vehicles included in this initial version have strong

near-term potential to realize significant fuel savings by adopting hybrid technology.

4 SAE International, Constant Volume Sampler System for Exhaust Emissions

Measurement - SAE Surface Vehicle Standard J1094, 1992.

5 Preliminary testing indicates dynamometer to track differences of about 4% with

coupled dynamometer rolls (10% with uncoupled rolls), on passenger vehicles.  This

difference may be explained by tire/surface interactions.  However, both track and chassis

dynamometer tests demonstrated directionally consistent and statistically equivalent

differences to changes in drive cycle for various vehicles. US Environmental Protection

Agency, Dynamometer and Track Measurement of Car Fuel Economy - EPA-460/3-81-

002, March, 1981.

6 Only a few chassis dynamometers exist that can accommodate tractor-trailer

combination trucks. Also, track tests directly factor aerodynamic effects; for the

highway-speed drive cycles typical of trailer-tractor combination trucks, aerodynamic

effects can have a significant impact on fuel consumption.

7 However, it has been demonstrated that even tests conducted in laboratories have

differences in repeatability within a given laboratory and differences in reproducibility

among laboratories. Reference "Interlaboratory Crosscheck of Heavy duty Vehicle

Chassis  Dynamometers" Final Report CRC Project No. E-55-1, May, 2002.

8 The transient drive cycles typical of single unit or truck body heavy duty vehicles are

likely to be more easily replicated on a chassis dynamometer than on a test track. A

reasonable number of chassis dynamometer facilities exist to accommodate lighter-

weight single unit or truck body heavy duty vehicles, partly because the federal

government established an optional chassis dynamometer emissions certification test for

engines  used  in heavy  duty vehicles up to 14,000 pounds GVWR.

9 SAE J1321 is a paired-truck test. This test procedure is single truck test.  Therefore, for

the SAE J1321 cites in this document, ignore references to two test vehicles.

10 To be comparable, each vehicle must be able to accomplish the same functions, with

similar performance, utility, and durability attributes.  In certain instances, comparability

may require selecting test vehicles produced by the same manufacturer. In other

instances, comparability may mean selecting test vehicles that are close competitors

within the same market niche. A test vehicle can be from a previous year relative to the

comparison vehicle, if the engine is functionally unchanged between the two years and if

                                                                              72

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all other vehicle characteristics are substantially similar, with the exception of the design

options being tested.

11 If a hand held wind indicator is used, it must have an accuracy equivalent to the wind-

sensing equipment available from Edmund Scientific Company, Harrington, NJ, or

Dwyer Instrument, Inc., Michigan City, IN.

  Use the correlation guidance established by EPA in its chassis dynamometer emissions

testing [get cite].

14 SAE Recommended Practice J2263. Road Load Measurement Using Onboard

Anemometry and Coastdown Techniques. October 1996.

15 SAE Procedure J2264. Chassis Dynamometer Simulation of Road Load Using

Coastdown Techniques., April, 1995.

16 SAE International, Constant Volume Sampler System for Exhaust Emissions

Measurement SAE Surface Vehicle Information Report J1094, revised June, 1992

17 Long-duration idling is not addressed in this drive cycle, since the objective is to

measure on-road fuel economy.  If idling fuel consumption is desired, the ARE idle mode

test is recommended.  There are many alternatives to overnight idling.  These include

truck stops that offer shore power (and HVAC); on-board auxiliary power units (APUs);

driver tag-teams. Strategies to reduce overnight idling can be found at

http://www.epa.gov/smartway/idling.htm.

  [reserved - ARB drive cycle cite]

 18

 19 See SAE 2002-01-1753, Development and Initial Use of a Heavy duty Diesel Truck

 Test Schedule for Emissions Characterization, Mridul Gautam, et al., and SAE 2006-01-

 3474 Fuel Economy Improvements andNOx Reduction by Reduction of Parasitic Losses:

 Effect of Engine Design, L. Joseph Bachman, et al.



 20

   SAE Surface Vehicle Information Report J1343, Information Relating to Duty Cycles

 and Average Power Requirements of Truck and Bus Engine Accessories, August, 2000;

 SAE SAE J1341, Test Method for Measuring Power Consumption of Hydraulic Pumps

for Trucks and Buses, July, 1981; SAE Jl 339, Test Method for Measuring Power

 Consumption of Truck and Bus Engine Fans, August, 2002; and,  Southwest Research

 Institute Final Letter Report, Emissions and Fuel Economy Testing of Three Utility

 Trucks, SwRI Project No. 03.11602, September, 2005.

 21 Average payload for class 8 over-the-road freight carriers in EPA SmartWay Transport

 Partnership.

 22 SAE Surface Vehicle Recommended Practice, Recommended Practice for Measuring

 Fuel Economy and Emissions of Hybrid-Electric and Conventional Heavy duty Vehicles,

 SAE J2711, September, 2002.

 01

   For a typical 5-axle tractor-trailer combination truck, applicable federal over-axle

 limits are 12,000 pounds on the steer axle, and 34,000 each on the drive and trailer axles,

 respectively.

 24 §3.7 of the SAE Surface Vehicle Recommended Practice, Recommended Practice for

 Measuring Fuel Economy and Emissions of Hybrid-Electric and  Conventional Heavy

 duty Vehicles, SAE J2711, September, 2002,

                                                                             73

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25  SAE J1711 §3.7, points out that to measure a fuel consumption value that is within

±3% of the vehicle's true, representative fuel consumption the change in energy stored in

the RESS must be less than ±1% of the total fuel energy consumed over the test cycle.



26 The value of k for a gas varies with pressure; the variation is significant at high

pressures.  EPA experimenters at the National Fuel and Vehicle Emissions Laboratory

have found that a value of 1.8 yields good results for nitrogen at pressures from 2000 to

5000 pounds per square inch - typical pressures for hybrid hydraulic accumulators. The

actual value has little impact on the calculation of NEC, however, if there is little

difference between starting and final accumulator pressure, and hence little difference in

starting and final SOC.



27 Clark, Nigel N., Xie, Wenwei, Gautam, Mridul, Lyons, Donald W., Norton, Paul, and

Balon, Thomas. Hybrid Diesel-Electric Heavy duty Bus Emissions: Benefits of

Regeneration and Need for State of Charge Correction.  SAE Paper No. 2000-02-2955.

Presented at the International Fall Fuels and Lubricants Meeting and Exposition.

Baltimore, MD. October 2000.



28 SAE Surface Vehicle Recommended Practice, Road Load Measurement and

Dynamometer Simulation Using Coastdown Techniques, February,  1996; SAE Surface

Vehicle Recommended Practice, Road Load Measurement Using Onboard Anemometry

and Coastdown Techniques,  October, 1996; SAE Surface Vehicle Recommended

Practice, Chassis Dynamometer Simulation of Road Load using Coastdown Techniques,

April, 1995.

OQ

  Southwest Research Institute, Testing and Analysis Support for the SmartWay

Transport Partnership, Final Report SwRI Project 08.1166.15.101,  June, 2006.

30 Op cit. Ref. Error! Bookmark not defined..



31 U.S. EPA (Environmental  Protection Agency). Guidance on Technical Audits and

 Related Assessments for Environmental Data Operations, EPA QA/G-7. EPA/600/R-

 99/080, http ://www. epa. gov/quality/qs-docs/g7-final .pdf.  Office of Environmental

 Information, U.S. Environmental Protection Agency. Washington, DC. January 2000.



32 U.S. EPA (Environmental Protection Agency). Guidance on Assessing Quality

Systems, EPA QA/G-3. EPA/240/R-03/002. http://www.epa.gov/qualitv/qs-docs/g3-

final.pdf. Office of Environmental Information, U.S. Environmental Protection Agency.

Washington, DC.  March 2003.

                                                                             74

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Created on 11/29/2007 3:38:00 PM











19.  List of Figures and Tables

                                                       75

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