Greenhouse Gas Emissions Model
(GEM) User Guide
&EPA
United States
Environmental Protection
Agency
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Greenhouse Gas Emissions Model
(GEM) User Guide
Assessment and Standards Division
Office of Transportation and Air Quality
U.S. Environmental Protection Agency
&EPA
United States EPA-420-B-10-039
Environmental Protection n , omn
Agency October 2010
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Greenhouse gas Emissions Model (GEM) User Guide
The Greenhouse gas Emissions Model was developed by EPA as a means for
determining compliance with the proposed GHG emissions and fuel consumption vehicle
standards for Class 7 and 8 combination tractors and Class 2b-8 vocational vehicles developed
by EPA and NHTSA respectively. The model itself is part of the proposed rule. See Section
II.B.2 of the preamble and Chapter 4 of the draft RIA. It is a free, desktop computer application.
GEM is designed to operate on a single computer. The downloadable installation file
located on the EPA website at http://www.epa.gov/otaq/climate/regulations.htm contains the
application executable file and other supporting files, which will be described in this guide. To
request a CD of this software instead of downloading it, or to request assistance if you have
trouble with accessibility of this software, please contact:
Assessment and Standards (ASD) Hotline at:
734-214-4636 or
Email: ASDInfo@epa.gov
This user guide contains the model documentation with details on the model's input files,
algorithms, and output files. It also includes instructions on how to use GEM. In addition, this
document includes the input file which was used to determine the baseline and proposed
greenhouse gas emissions and fuel efficiency standards for Class 7 and 8 tractors and Class 2b-8
heavy-duty vehicles. Some of the information provided here are also contained in Chapter 4 of
the draft RIA.
1. GEM Documentation vl.O
This section describes the GEM vehicle model architecture, the list of pre-defined input
parameters, output calculations, and the installation and usage of the MATLAB/Simulink version
of GEM.
1.1. Vehicle Model Architecture
Table 1 outlines the Class 2b-8 vehicle compliance model architecture, which is
comprised of six systems: Ambient, Driver, Electric, Engine, Transmission, and Vehicle. With
the exception of "Ambient" and "Driver," each system consists of two to four component
models. The function of each system and their respective component models, wherever
applicable, is discussed in this section.
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Table 1: Vehicle Model Architecture
System Component Models
Ambient
Driver
Electric
Engine
Transmission
Vehicle
none
none
Starter; Electrical Energy System; Alternator; Accessory (electrical)
Cylinder; Accessory (mechanical)
Clutch; Gearbox
Chassis; Final Drive
Ambient - This system defines ambient conditions such as pressure, temperature, and
road gradient, where vehicle operations are simulated.
Driver - GEM is a forward-looking driving model. Rather than constantly matching the
exact drive cycle, the driver model considers the current speed and the desired future
speed to try to predict the necessary power required to close the gap and follow the
driving trace. If the driver misses the target, a different power request is sent to the
engine and/or brakes are applied. This search for the proper vehicle speed occurs at
every simulation time step. The feedback loop uses a PID controller.
The "Electric" system consists of four components: Starter, Electrical Energy System,
Alternator, and Electrical Accessory
o Starter - This models the starter for the engine, which is identical for most
vehicles.
o Electrical Energy System - GEM simulates a standard 12 or 24 volt lead-acid
battery, which provides currents to the starter and electrical systems for engine
starting, lighting, and vehicle controls. This module estimates State-of-Charge
(SOC), internal ohmic resistance and open circuit voltage, voltage and current of
electrical energy storage system.
o Alternator - This models the alternator that generates electricity for the battery
and electrical system. The model calculates voltage and current of the AC
alternator based on alternator performance maps and charge control strategy.
o Electrical Accessory - All vehicles have a number of electrical loads, some of
which are necessary to operate the vehicle. The engine control unit (ECU), fuel
injectors and fuel pump for instance are electrical loads that are constantly on the
battery, and these are already taken into account in the fuel map.
The "Engine" system consists of two components: Cylinder and Mechanical Accessory
o Cylinder - The cylinder model is based on a fuel map and torque curves at wide
open throttle (full load) and closed throttle (no load). The engine fuel map
features three sets of data: engine speed, torque, and fueling rate at pre-specified
engine speed and torque intervals. The fuel map was developed from
experimental results adjusted to reflect projected future engine performance. It is
not a physics-based model and does not attempt to model in-cylinder combustion
process. The engine torque and speed are used to select a fuel rate based on the
fuel map. This map is adjusted automatically by taking into account three
different driving types: acceleration, braking, and coasting. The fuel map, torque
curves, and the different driving types can be adjusted by the user, but there are a
number of default engines pre-programmed into GEM.
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o Mechanical Accessory - Most vehicles run a number of accessories that are
driven via mechanical power from the engine. Some of these accessories are
necessary for the vehicle to run, like the coolant pump, while others are only used
occasionally and at the operator's discretion such as the air conditioning
compressor. Some heavy-duty vehicles also use Power Take Off (PTO) to
operate auxiliary equipment, like booms, and these would also be modeled as a
mechanical accessory.
The manual "Transmission" system consists of two components: a Clutch and a Gearbox
o Clutch - This component model simulates the clutch for a manual transmission.
o Gearbox - A simple gearbox model is used for a manual transmission, and the
number of gears and gear ratios are predefined for compliance purposes. This
component model consists of a map using gearbox speed and torque as inputs to
model the efficiency of each gear.
The "Vehicle" system consists of two components: Chassis and Final Drive
o Chassis - This portion models the shell of the vehicle including the tires. The
drag coefficient, mass of the vehicle, frontal area and other parameters are housed
in this component. For tire simulation, the user specifies the configuration of
each axle on the vehicle, including the tire diameter and the rolling resistance.
o Final Drive - The gear ratio for the differential is predefined for compliance
purposes. The efficiency is defined by a map based on the transmission output
speed and torque.
1.2. List of Predefined Input Parameters for Class 7/8 Combination
Tractor Models
Although many technologies can potentially achieve GHG emission and fuel
consumption reductions, EPA and NHTSA are of the initial view that for the rule's proposed
timeframe, some may be too complex to model (e.g., hybrid control) while others require
standardization such as the calculation of GHG and fuel consumption benefits due to
aerodynamic improvements which would require an input for the tractor frontal area. To better
capture the GHG emission and fuel consumption benefits in the simulation model as well as to
avoid unintended consequences in the real world, the agencies have identified a set of parameters
that are consistent across various manufacturers for this rulemaking period and are proposing
that these parameters be used as predefined inputs to the model. EPA and NHTSA are proposing
to standardize the tractor frontal area, tractor-trailer total and payload weight, gear box and its
efficiency, final drive ratio, engine/transmission/wheel inertia, accessory load, axle base, tire
radius, trailer tire coefficient of rolling resistance (Crr, trailer tires), and engine fuel map. The
agencies are proposing to use these standardized input parameters in the simulation model for all
seven proposed subcategories of combination tractors. The predefined values, if finalized, then
will remain in force unless and until EPA and NHTSA amend the rule to change the values.
Table 2 lists the specific values of these parameters.
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Table 2: Combination Tractor Modeling Input Parameters
MODEL TYPE
Regulatory
Subcategory
Fuel Map
Gearbox
Gearbox Ratio
Gearbox
Efficiency
Engine Inertia
(kg-m2)
Transmission
Inertia (kg-m2)
All Axle Inertia
(kg-m2)
Loaded Tire
Radius (m)
Body Mass (kg)
Cargo Mass (kg)
Total weight (kg)
Total weight (Ibs)
Frontal Area (m2)
Coefficient of
Aerodynamic
Drag
Axle Base
Electrical
Accessory Power
Mechanical
Accessory Power
Final Drive Ratio
Tire CRR
(kg/metric ton)
Trailer Tire CRR
(kg/metric ton)
Steer Tire CRR
(kg/metric ton)
Drive Tire CRR
(kg/metric ton)
Vehicle Speed
Limiter (mph)
CLASS 8
Sleeper Cab
High Roof
10-speed
Manual
14.*
0.96
4.17
0.2
360
0.489
14742
17236
31978
70500
9.8
OEM Input
5
360
1000
2.64
6
OEM Input
OEM Input
OEM Input
CLASS 8
Sleeper Cab
Mid Roof
10-speed
Manual
5, 10.95, 8.09, £
0.96, 0.96, 0.9
4.17
0.2
360
0.489
13041
17236
30277
66750
7.7
OEM Input
5
360
1000
2.64
= 0.425
6
OEM Input
OEM Input
OEM Input
CLASS 8
Sleeper Cab
Low Roof
15L-455HP
10-speed
Manual
.97, 4.46, 3.32
6, 0.98, 0.98, 0
4.17
0.2
360
0.489
13154
17236
30391
67000
6
OEM Input
5
360
1000
2.64
x Trailer CRR +
6
OEM Input
OEM Input
OEM Input
CLASS 8
Day Cab
High Roof
10-speed
Manual
2.45, 1.81, 1.
98, 0.98, 0.98
4.17
0.2
360
0.489
14061
17236
31298
69000
9.8
OEM Input
5
360
1000
2.64
0.425 x Drive
6
OEM Input
OEM Input
OEM Input
CLASS 8
Day Cab
Low/Mid Roof
10-speed
Manual
35, 1
,0.98
4.17
0.2
360
0.489
12474
17236
29710
65500
6
OEM Input
5
360
1000
2.64
CRR + 0.15 x st
6
OEM Input
OEM Input
OEM Input
CLASS 7
Day Cab
High Roof
11L-
10-speed
Manual
11.06, 8. 1<
3.34, 2.48,
0
0.96, 0.96, 0
0.98, 0.98, 0
3.36
0.2
233.4
0.489
11340
11340
22680
50000
9.8
OEM Input
4
360
1000
3.73
eerCRR
6
OEM Input
OEM Input
OEM Input
CLASS 7
Day Cab
Low/Mid Roof
350 HP
10-speed
Manual
3, 6.05, 4.46,
1.83, 1.36, 1,
.75
96, 0.96, 0.98,
.98, 0.98, 0.98
3.36
0.2
233.4
0.489
9752
11340
21092
46500
6
OEM Input
4
360
1000
3.73
6
OEM Input
OEM Input
OEM Input
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1.3. List of Predefined Input Parameters for Class 2b-8 Vocational
Vehicle Models
Likewise, EPA and NHTSA are proposing to standardize a set of parameters for the three
proposed Class 2b-8 vocational vehicle types, which the agencies refer to as Vocational Light-
Heavy (VLH), Vocational Medium-Heavy (VMH), and Vocational Heavy-Heavy (VHH). These
predefined parameters include the coefficient of aerodynamic drag, truck frontal area, truck total
and payload weight, the gear box and its efficiency, final drive ratio, engine/transmission/wheel
inertia, accessory load, axle base, tire radius, and the engine fuel map. The predefined values, if
finalized, then will remain in force unless and until EPA and NHTSA amend the rule to change
the values. The specific values of these parameters are listed in Table 3.
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Table 3: Vocational Vehicle Modeling Input Parameters
Model Type
Regulatory
Subcategory
Fuel Map
Gearbox
Gearbox Ratio
Gearbox Efficiency
Engine Inertia (kg-m2)
Transmission Inertia
(kg-m2)
All Axle Inertia (kg-m2)
Loaded Tire Radius (m)
Body Mass (kg)
Cargo Mass (kg)
Total weight (kg)
Total weight (Ibs)
Frontal Area (m2)
Coefficient of
Aerodynamic Drag
Axle Base
Electrical Accessory
Power (W)
Mechanical Accessory
Power (W)
Final Drive Ratio
Tire CRR
(kg/ton)
Trailer Tire CRR
(kg/metric ton)
Steer Tire CRR
(kg/metric ton)
Drive Tire CRR
(kg/metric ton)
Heavy Heavy-Duty
Vocational Truck
(Class 8)
15L-455HP
10-speed Manual
14.8, 10.95, 8.09,5.97,4.46,
3.32,2.45, 1.81, 1.35, 1
0.96, 0.96, 0.96, 0.96, 0.98,
0.98, 0.98, 0.98, 0.98, 0.98
4.17
0.2
200
0.489
13154
17236
30391
67000
9.8
0.7
3
360
1000
2.64
Medium Heavy-Duty
Vocational Truck
(Class 6-7)
7L-270HP
6-speed Manual
9.01,5.27,3.22,
2.04, 1.36, 1
0.92, 0.92, 0.93,
0.95, 0.95, 0.95
2.79
0.1
60
0.389
6328
5080
11408
25150
9
0.6
2
360
1000
3.36
Light Heavy-Duty
Vocational Truck
(Class 2b-5)
7L-200HP
6-speed Manual
9.01,5.27,3.22,
2.04, 1.36, 1
0.92, 0.92, 0.93,
0.95, 0.95, 0.95
2.79
0.1
60
0.378
4672
2585
7257
16000
9
0.6
2
360
1000
3.25
= 0.5 x Drive CRR + 0.5 x steer CRR
Not applicable Not applicable Not applicable
OEM Input OEM Input OEM Input
OEM Input OEM Input OEM Input
1.4. Output Processes
The outputs produced by GEM include post processes to calculate the final weighted results.
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GEM produces a cycle-weighted gram CO2/ton-mile and gallon/1000 ton-mile result which
incorporates the proposed drive cycle weightings of the ARB transient cycle, 55 mph steady state
cruise, and 65 mph steady state cruise cycle, as shown in Table 4.
Table 4: Drive Cycle Weighting
CATEGORY
ARB Transient
55 mph Cruise
65 mph Cruise
CLASS 8
SLEEPER CAB
TRACTORS
5%
9%
86%
CLASS 7/8
DAY CAB
TRACTORS
19%
17%
64%
CLASS 2b-8
VOCATIONAL
VEHICLES
42%
21%
37%
GEM converts the mile per gallon result into ton-mile space by using the proposed
payload for each regulatory class - 19 tons for Class 8 tractors, 12.5 tons for Class 7 tractors, 19
tons for HHD vocational vehicles, 5.6 tons for MHD vocational vehicles, and 2.85 tons for LHD
vocation vehicles.
GEM calculates the gallons/1000 ton-mile weighted result by converting the weighted grams
CCVton-mile result. The gram CCVton-mile result is multiplied by 1000 and divided by 10,180
grams CC>2 per gallon of diesel fuel.
2. Instructions on How to Install and Use GEM
The executable form of GEM can be downloaded from the website. Please follow the
procedure below to run the executable version.
1. Unzip the file (GEM Setup.zip), and run the executable "GEM_Run.exe".
2. If the executable file runs and launches a Graphical User Interface (GUI) as shown in
Figure 1, then your computer system is ready to run the model.
3. If you receive the error message "application configuration is incorrect," then run
"setup.bat". The error message is related to missing system Visual Studio Redistributable
dll files and "setup.bat" will automatically run the Microsoft vcredist_x86.exe on the
client systems experiencing this issue.
4. Now, rerun the executable file "GEM_Run.exe". You should be able to see the GUI as
shown in Figure 1.
5. The simulation output is created in a folder "C:\GEM_Results\Month_Day_Year-Time".
The output file in XML format can be opened with Excel to see the results. Each
simulation creates a different folder using the above naming format.
The GEM input screen, as shown in Figure 1, provides the user the ability to enter the
required parameters into the model. There are essentially two types of parameters - ones
required for information and ones which impact the model. The first set of parameters which are
required to provide information to EPA and NHTSA and where GEM copies the information
from the input screen to the output screen. These include the following:
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• Manufacturer Name
• Email Address
• Date
• VERIFY User ID
• VERIFY ID
• Vehicle Family
• Vehicle Subfamily
• Engine Family
• Engine Subfamily
• Engine Model Year
The second set of parameters affects how GEM calculates the final result. The list below
describes each input and how it is used within GEM.
• Vehicle Model Year: The pull-down allows the user to select either Pre 2014 MY,
2014-2016 MY, or Post 2017 MY. The Vehicle Model Year selects the appropriate
fuel map in the model. The Pre 2014 MY allows users to evaluate the baseline
heavy-duty vehicle's engine fuel map. The 2014-2016 MY selection uses the engine
fuel maps which meet the proposed 2014 MY engine standards. The Post 2017 MY
option uses engine fuel maps which meet the 2017 MY proposed engine standards.
• Regulatory Class: The user must select one of the designated regulatory
subcategories. The selection leads the model to use the appropriate predefined inputs
and post processing parameters, as outlined in Sections 1.2, 1.3, and 1.4 of this
Guidance.
• Coefficient of Drag: The Cd value is input by the user based on the proposed
aerodynamic bins, as discussed in both the preamble and draft RIA. This input is
only required for combination tractors. No input is required for vocational trucks.
• Steer Tire Rolling Resistance: The coefficient of rolling resistance for the steer tires
should be input by the user in terms of kg/metric ton. Please note that the units are in
kg/metric ton where the typical value is greater than 5.5 kg/metric ton. The units are
not in kg/kg or Ib/lb (the other industry norm) where the values are typically greater
than 0.0055 kg/kg or Ib/lb.
• Drive Tire Rolling Resistance: The coefficient of rolling resistance for the drive tires
should be input by the user in terms of kg/metric ton. Please note that the units are in
kg/metric ton where the typical value is greater than 5.5 kg/metric ton. The units are
not in kg/kg or Ib/lb (the other industry norm) where the values are typically greater
than 0.0055 kg/kg or Ib/lb.
• Vehicle Speed Limiter: If the vehicle contains a vehicle speed limiter, then the setting
corresponding to the nearest whole mile per hour should be selected. GEM will limit
the maximum speed of the vehicle to the value selected. This input is only available
for combination tractors. No input is allowed for vocational trucks.
• Vehicle Weight Reduction: If a combination tractor contains lighter weight wheels or
tires, as described in the preamble, draft RIA, and regulations, then the user would
input the sum of the weight reductions prescribed by the weight bins. This input is
only available for combination tractors. No input is allowed for vocational trucks.
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Extended Idle Reduction: If a sleeper cab combination tractor contains an extended
idle reduction technology and a 5 minute automatic engine shut-off, then the user
would select the 5 g/ton-mile reduction. If not, then 0 should be selected. This input
is only available for sleeper cab combination tractors. No input is allowed for day
cab combination tractors or vocational vehicles.
iS*- Greenhouse gas Emissions Model (GEM) v1.0
Greenhouse gas Emissions Model (GEM) vl.O
Identification
Manufacturer Name
VERIFY User ID:
Vehicle Family:
Engine Family:
E-mail Address:
VERIFY ID:
Vehicle Sub Family:
Engine Sub Family: [
(Date)
Vehicle Model Year:
Engine Model Year: j
Regulatory Class
O Class 6 Combination - Sleeper Cab • High Roof
O Class 6 Combination - Sleeper Cab • Mid Roof
O Class 6 Combination - Sleeper Cab • Low Roof
O Class 8 Combination - Day Cab - High Roof
O Class 8 Combination - Day Cab - Low/Mid Roof
O Class 7 Combination - Day Cab - High Roof
O Class 7 Combination - Day Cab - Low/Mid Roof
O Heavy Heavy-Duty - Vocational Truck (Class 8)
O Medium Heavy-Duty - Vocational Truck (Class 6-7)
O Light Heavy-Duty - Vocational Truck (Class 2b-5)
Simulation Inputs
Coefficient of Aerodynamic Drag
Steer Tire Rolling Resistance [kg/metric ton]
Drive Tire Rolling Resistance (kg/metric ton]
Vehicle Speed Umiler [mph]
Vehicle Weight Reduction [Ibs]
Extended Idle Reduction [gram C02/ton-mile]
Figure 1 - GEM Input Screen
After the user selects "RUN," GEM will conduct the simulation of each of the drive
cycles. The output will provide both the gram CCVton-mile and gallon/1000 ton-mile result in
the .xml file, as shown in Figure 2. The simulation output is created in a folder
"C:\GEM_Results\Month_Day_Year-Time." The output file is in xml format and can be opened
with Excel. Each simulation creates a different folder using the "Month_Day_Year-Time"
naming format.
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Greenhouse gas Emissions Model (GEM) Simulation Results
Manufacturer Name:
VERIFY User ID:
Vehicle Fam%:
Engine Family:
MANUFACTURER IDENTIFICATION
E-mail Address
VERIFY ID:
Vehicle Sub Family:
Engine Sub Family:
Vehicle Model Year:
Engine Model Year:
SIMULA TION INPUTS
Class 3 Combination - Sleeper Cab - High Roof
0.85
Percent Time Missed by 2mph [%]
Fuel Consumption far Entire Cycle [mpg]
C02 Emissions [g/ton-mite]
SIMULATION OUTPUTS
Model Year = 2014
Transient Cycle Simulation
0.31
145.25
55 mph Steady-State Cycle Simulation
Percent ~ime Missed by 2mph [%] 0
Fuel Consumption during Steady State [mpg] 7.39
C02 Emissions [g/ton-mite] 72 52
65 mph Steady-State Cycle Simulation
Percent Time Missed by 2mph [%] 0
Fuel Consumption during Steady State [mpg] 6.04
C02 Emissions [g/ton-mite] S-S.66
Weighted Fuel Consumption [mpgj
--> in ga^1000ton-miie
VVeighted C02 Emission [g/1000 ton-mile]
Cycle-Weighted Results
8.84
90.0*
Figure 2 - Sample GEM Output .xml File
3. MATLAB/Simulink Version of GEM
In addition to providing executable file which the agencies have proposed to be used for
certification purposes, the agencies are also furnishing a MATLAB/Simulink version of GEM to
allow stakeholders to review the model architecture in detail. The system requirements for GEM
include a minimum RAM of 1 GB, MATLAB, Simulink and Stateflow (version 2009b or later).
1 o Q
and approximately 250 MB of disk storage. ' ' No separate license is required to run the
program other than for MATLAB, Simulink, and Stateflow. Although the source code is
available to users, all of the component initialization files, control strategies and the underlying
MATLAB/Simulink/Stateflow-based models should remain fixed and should not be manipulated
by the users when assessing their compliance. For these reasons, the stand-alone executable
model independent of MATLAB/Simulink/Stateflow licenses has been created. The agencies
recommend using the executable file for the evaluation of various truck configurations, as it was
developed for the end user.
3.1 Installation Instructions for the MATLAB/Simulink Version
Copy the entire directory from the web link into the user's hard drive, then follow the
procedures below.
1 http://www.mathworks.com/products/matlab © 1994-2010 The MathWorks, Inc.
2 http://www.mathworks.com/products/simulink © 1994-2010 The MathWorks, Inc.
3 http://www.mathworks.com/products/stateflow © 1994-2010 The MathWorks, Inc.
10
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1. Start the MATLAB and change the current directory to the location where the tool is
unzipped and saved.
2. Run the MATLAB script "Run_GEM_sim.m" to launch the GUI window to start using
the tool.
3. Select one radial button on the left-hand side of the window to choose an appropriate
truck subcategory.
4. Enter proper values for "Coefficient of Aerodynamic Drag," "Steer Tire Rolling
Resistance," and "Drive Tire Rolling Resistance" on the right-hand side of the window
(see Section 2 above which describes each input).
5. Click the "RUN" button. Then, the tool will simulate the three different driving cycles
(ARE transient, 55 mph, and 65 mph) and display the final results in the Matlab
Command Window. The tool will also display plots of vehicle speed for all three cycles.
3.2 Input File Structures
The programs that are downloaded from website consist of the following files in the main
directory:
Run_GEM_sim.m: a Matlab file used to launch the simulation
GEM_manual_vl.mdl: Simulink file containing vehicle and all submodels
run_preproc.m
run_postproc.m
GEM_sim.m
run_55mph.m
run_65mph.m
run_transient.m
drive_cycles folder
executable folder
param_files folder
4. Input Files Used to Calculate the Proposed GHG Emissions and Fuel
Efficiency Standards
The agencies developed the baseline and proposed standards using the input tables included
in Table 5 and Table 6.
11
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Table 5: Input Parameters for Proposed Tractor Standards
CLASS
Regulatory
Subcategory
CLASS 8
Sleeper Cab
High Roof
CLASS 8
Sleeper Cab
Mid Roof
CLASS 8
Sleeper Cab
Low Roof
CLASS 8
Day Cab
High Roof
CLASS 8
Day Cab
Low/Mid Roof
CLASS 7
Day Cab
High Roof
CLASS 7
Day Cab
Low/Mid Roof
Baseline
Fuel Map
Cd
Steer Tire CRR
Drive Tire CRR
Weight Reduction
(Ibs)
Extended Idle
2010 MY
0.69
7.8
8.2
0
None
2010 MY
0.76
7.8
8.2
0
None
2010 MY
0.81
7.8
8.2
0
None
2010 MY
0.69
7.8
8.2
0
N/A
2010 MY
0.81
7.8
8.2
0
N/A
2010 MY
0.69
7.8
8.2
0
N/A
2010 MY
0.81
7.8
8.2
0
N/A
2074 MY Proposed Standard
Fuel Map
Cd
Steer Tire CRR
Drive Tire CRR
Weight Reduction
(Ibs)
Extended Idle
201 4 MY
0.60
6.54
6.92
400
Yes
201 4 MY
0.72
6.87
7.26
400
Yes
201 4 MY
0.76
6.87
7.26
400
Yes
201 4 MY
0.62
6.87
7.26
400
N/A
201 4 MY
0.77
6.99
7.38
400
N/A
201 4 MY
0.62
6.87
7.26
400
N/A
201 4 MY
0.77
6.99
7.38
400
N/A
2077 MY Proposed Standard
Fuel Map
Cd
Steer Tire CRR
Drive Tire CRR
Weight Reduction
(Ibs)
Extended Idle
201 7 MY
0.60
6.54
6.92
400
Yes
201 7 MY
0.72
6.87
7.26
400
Yes
201 7 MY
0.76
6.87
7.26
400
Yes
201 7 MY
0.62
6.87
7.26
400
N/A
201 7 MY
0.77
6.99
7.38
400
N/A
201 7 MY
0.62
6.87
7.26
400
N/A
201 7 MY
0.77
6.99
7.38
400
N/A
12
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Table 6: Input Parameters for Proposed Vocational Vehicle Standards
Model Type
Regulatory Subcategory
Heavy Heavy-Duty
Vocation Truck
(Class 8)
Medium Heavy-Duty
Vocation Truck
(Class 6-7)
Light Heavy-Duty
Vocation Truck
(Class 2b-5)
Baseline
Fuel Map
Tire CRR (kg/metric ton)
2010 MY
9.0
2010 MY
9.0
2010 MY
9.0
2074 MY Proposed Standard
Fuel Map
Tire CRR (kg/metric ton)
201 4 MY
8.1
201 4 MY
8.1
201 4 MY
8.1
2077 MY Proposed Standard
Fuel Map
Tire CRR (kg/metric ton)
201 7 MY
8.1
201 7 MY
8.1
201 7 MY
8.1
13
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