Greenhouse Gas Emissions Model
(GEM) User Manual
Vehicle Simulation Tool for Compliance
with the Proposed Greenhouse Gas
Emissions Standards and Fuel Efficiency
Standards for Medium and Heavy-Duty
Engines andVehicles: Phase 2
&EPA
United States
Environmental Protection
Agency
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Greenhouse Gas Emissions Model
(GEM) User Manual
Vehicle Simulation Tool for Compliance
with the Proposed Greenhouse Gas
Emissions Standards and Fuel Efficiency
Standards for Medium and Heavy-Duty
Engines andVehicles: Phase 2
Assessment and Standards Division
Office of Transportation and Air Quality
U.S. Environmental Protection Agency
&EPA
United States
Environmental Protection
Agency
EPA-420-B-15-076
June 2015
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Table of Contents
Table of Contents 3
Introduction 4
Installation 4
Computer Requirements 4
Installation Instructions 4
Contents of Installation Package 9
Sample Input Files 10
GEM Executable 11
Model Description 11
Vehicle Parameters for Each Regulatory Subcategory 13
Drive Cycles and Transient Correction Factor 13
Tractor Vehicle Parameters 14
Vocational Vehicle Parameters 16
Trailer Vehicle Parameters 19
GEM Input File Structure 21
Note to Users Creating or Editing .csv Files Using Microsoft Excel 22
Tractor Input Files 22
Vocational Input Files 26
Trailer Input Files 30
Supplemental Input Files 32
Engine Input File for Tractor and Vocational Vehicles 32
Transmission Input File for Tractor and Vocational Vehicles 34
Optional Powertrain Input File for Tractor and Vocational Vehicles 34
GEM Output File Structure 36
Running GEM 36
Preparing for GEM Runs 37
Special Instructions for Heavy-Haul Tractor Manufacturers 37
Special Instructions for Vocational Emergency Vehicle Manufacturers 37
Accessing Output Files 37
Running GEM Using the Start Menu and Desktop Icon 37
Running GEM Using the Command Prompt 42
Running GEM from Microsoft Excel 46
Final Notes 48
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Introduction
The Greenhouse gas Emissions Model (GEM) was first created by EPA as part of the
"Heavy-Duty Greenhouse Gas Emissions Standards and Fuel Efficiency Standards for Medium-
and Heavy-Duty Engines and Vehicles: Phase 1" rulemaking finalized in 2011. The model was
developed to serve as a means for determining compliance with EPA's GHG emissions and
NHTSA's fuel consumption vehicle standards for Class 7 and 8 combination tractors and Class
2b-8 vocational vehicles. Since then, significant improvements have been made to the model for
the Phase 2 proposed rulemaking.
This user guide contains the model documentation, including a summary of the upgrades
from GEM version 2.0.1 (i.e., "Phase 1 GEM"), installation instructions, and instructions for
running the model, including a description of the necessary input and resulting output files. A
detailed description of the model architecture and updates can be found in Chapter 4 of the draft
RIA.
Installation
C o Re fi u I re rue nts
EPA developed Phase 2 GEM to be a forward-looking Matlab/Simulink-based model for
heavy-duty (Class 2b-8) vehicle compliance for the Phase 2 proposed rulemaking. The model is
a free, desktop computer application provided as an executable to be operated on a single
computer. Since it is provided as an executable, the user does not have to have access to the
Matlab/Simulink software packages. However, the following minimum computer specifications
are required for the model to run:
— Operating System: Windows 7 or newer
- CPU: 2 GHz processor
- Memory: 4 GB of RAM
The downloadable installation file is available on EPA's website (see Figure 1) at:
http://www. epa.£ov/otaq/climate/£em. htm.
A link to the most recent GEM version will be located at the top of the page. The GEM
executable is bundled with the user guide and input file templates into a 600 MB file that can be
downloaded in a single step. The user guide is also available on the website for convenience.
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 request through an email addressed to
OTAQPUBLICWEB@epa.gov.
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* Measuring Greenhouse Gas Emissions from Transportation
"Greenhouse Gas Emissions Model (GEM) for Medium- and Heai/y-Duty Vehicle Compliance
Greenhouse Gas Emissions Model (GEM) for Medium-
and Heavy-Duty Vehicle Compliance
EPA's Greenhouse Gas Emissions Model (GEM) is a free, desktop computer
application that estimates the greenhouse gas (GHG) emissions and fuel
efficiency performance of specific aspects of heavy-duty vehicles. GEM is
designed to operate on a single computer.
NOTE You will need Adob* Acrobat
Reader, available as a free download,
to uj«w some of the files on thts page
Sc« EPA's PDF page to learn more
about PDF, and for & link to the free
Acrobat Reader
To request a CD of this software instead of downloading it or if you have trouble
with accessibility of this software, please contact EPA.
Mew! Phase 2 GEM Simulation Model (Supporting the Final Heavy-Duty Vehicle Greenhouse
Gas Emissions and Fuel Efficiency Rules)
The model documentation provides details on how to install and use the model. The pdf file also contains the Input files
that were used to determine the stringency of the final Greenhouse Gas Emissions Standards and Fuel Efficiency
Standards for Medium- and Heavy-Duty vehicles. The downloadable installation file below contains the application
executable files for the active version of Phase 2 GEM for simulating vehicle compliance. Lastly, the report of the peer
review on GEM includes the comments received on The model and EPA's responses.
• Read the user guide for model architecture, how to use the modeJ, and inputs used to determine the final
standards (PDF) (xxpp, »X*K, EPA-420-8-15-076,June20lS)
• Download the executable version of GEM_Setup_x64.exs Mp'ir''' inry 2015)
• Peer Review Report and Response to Comments (PDF) (x>: pp. o ^>ts/^-<£-R-15-009, June 2015) This document
contains the Peer Review Report, which is comprised of comments frornitZr separate peer reviewers, and EPA's
response to those comments.
GEM Simulation Model v2.Q.1 (Supporting the Final Heavy-Duty Vehicle Greenhouse Gas
Emissions and Fuel Efficiency Rules)
The model documentation provides details on how to install and use the mode). The pdf file also contains the Input files
Figure 1: EPA Website to Obtain GEM Installation Package
Currently, GEM is only available to computers using 64-bit Windows operating systems
(Windows 7 and newer). To check your computer's operating system, right click on "Computer"
from a desktop icon or the Windows Start Menu to pull up the System Properties window. If
your computer has a 64-bit operating system, it will be noted on the properties window, as is
seen in Figure 2.
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To install GEM, download the installation file from EPA's website. Once downloaded,
double-click the "GEM_P2vl.O_Setup_x64" executable to start the setup wizard that will walk
you through the steps of installation.
I Setup - Phase 2 GEM
Welcome to the Phase 2 GEM
Setup Wizard
This will install Phase 2 GEM version 1,0 on your computer.
It is recommended that you dose all other applications before
continuing,
Click Next to continue, or Cancel to exit Setup,
Figure 3: Welcome Window for the Setup Wizard for Phase 2 GEM
Users have the option of choosing a separate location for their Phase 2 GEM installation,
but we recommend the default folders and shortcuts, as seen in Figure 4 and Figure 5. The
instructions throughout this user guide assume the user installed Phase 2 GEM in the default
locations with its default folder names.
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Select Destination Location
Where should Phase 2 GEM be installed?
Setup will install Phase 2 GEM into the following folder.
To continue, dick Next. If you would like to select a different folder, dick Browse.
Browse.,
At least 680.5 MB of free disk space is required.
< Back Next > Cancel
Figure 4: Destination for Phase 2 GEM Download; the Agencies Recommend the Default Location
Select Start Menu Folder
Where should Setup place the program's shortcuts?
Setup will create the program's shortcuts in the following Start Menu folder.
To continue, dick Next. If you would like to select a different folder, didt Browse,
Browse...
< Back Next >
Cancel
Figure 5: Start Menu Folder for Phase 2 GEM Download; the Agencies Recommend the Default Folder
Name
The next screen gives users an option to create a shortcut to Phase 2 GEM on their
desktop. Users that choose to install a desktop icon will see a "Phase 2 GEM" shortcut, similar
to the one shown in Figure 6, on their desktop. Users can uncheck the box next to the "Create a
desktop icon" if they do not wish to have a desktop shortcut.
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Figure 6: Desktop Icon Shortcut to Phase 2 GEM
Phase 2 GEM requires the use of Matlab Runtime Compiler and Microsoft Visual C++
2005 or 2008 Redistributable (x64). The setup wizard will install Matlab Runtime Compiler
R2014a (version 8.3) if the box, shown in Figure 7, is checked. For computers that already have
the runtime compiler (R2014a or newer) installed, users can uncheck this box to avoid
reinstallation.
Select Additional Tasks
Which additional tasks should be performed?
Select the additional tasks you would like Setup to perform while installing Phase 2
GEM, then dick Next.
Additional icons:
[Vj £re5i.e .5 ce?ktop icon!
Dependencies
|5] Install Matlab Compiler Runtime
Cancel
Figure 7: Additional Installation Options for Phase 2 GEM; Matlab Runtime Compiler R2014a or Newer is
Required for GEM Use
The following windows allow users to review the installation settings and install Phase 2
GEM. The installer will warn users if their computers do not have Microsoft Visual C++ 2005
or 2008 Redistributable (x64) installed. A pop-up window will initiate installation of this
software and will remain displayed until installation is complete.
A final screen (Figure 8) will show up when Phase 2 GEM has completed installing. The
installation process for Matlab Runtime Compiler (if selected) will initiate shortly after this
completion screen appears. The Matlab setup wizard for the runtime compiler is not described in
this user guide.
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ig) Setup - Phase 2 GEM
Completing the Phase 2 GEM
Setup Wizard
Setup has finished installing Phase 2 GEM on your computer
The application may be launched by selecting the installed
icons,
Click Finish to exit Setup,
Figure 8: Installation Complete Window for Phase 2 GEM
Contents of Installation Package
Once installed, several files are stored in the installation location selected (i.e.,
C:\Program FilesYUS EPAVPhase 2 GEM\ by default). Figure 9 shows the contents of the default
installation folder. Users can access the GEM User Guide, the GEM executables, and sample
files from this directory. They can also uninstall GEM and remove all of its contents by clicking
on the "uninsOOO.exe" executable.
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Figure 9: Contents of Installation Folder for Phase 2 GEM
GEM is also available from the Start Menu, under the folder named "EPA Phase 2
GEM", as seen in Figure 10. Within the Start Menu folder, users have access to the executable,
as well as a copy of this User Guide, a link to the EPA website, and sample input files that can be
used as templates for running GEM.
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ji Window: Media Player
, Accessories
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Administrative Tools
Cisco IPTV Viewer
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EPA Phase I GEM
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Figure 10: Start Menu Location of GEM
Sample Input Files
Sample input files are stored with the Phase 2 GEM executable. Within the "Sample
Input Files - RELOCATE BEFORE USE" folder, the agencies provide sample files for each of
the three vehicle regulatory subcategories that use GEM: Tractor, Trailer, and Vocational
vehicles. The following documents will be available in three folders:
- Tractor sample files folder
o Sample engine input file: EPA Sample 3SOhp.csv
o Sample engine input file: EPA Sample 455hp.csv
o Sample transmission input file: EPA Sample AMT.csv
o Sample transmission input file: EPA Sample_MT.csv
o Sample vehicle input file: GEM TRACTOR.csv
o Sample vehicle Excel macro file: GEM TRACTORxlsm
— Trailer sample files folder
o Sample vehicle input file: GEM TRAILER.csv
o Sample vehicle Excel macro file: GEM TRAILER.xlsm
— Vocational sample files folder
o Sample engine input file: EPA Sample 200hp.csv
o Sample engine input file: EPA Sample 27Ohp.csv
o Sample engine input file: EPA Sample 345hp.csv
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o Sample engine input file: EPA Sample 455hp.csv
o Sample transmission input file: EPA Sample AT 5 HHD.csv
o Sample transmission input file: EPA Sample AT 5 MLHD.csv
o Sample transmission input file: EPA Sample MT 10 HHD.csv
o Sample vehicle input file: GEM VOCATIONAL.csv
o Sample vehicle Excel macro file: GEM VOCATIONAL.xlsm
A description of each of these input files and instructions for running the model are
provided in later sections.
If users select the default installation folder, C:\Program FilesMJS EPAVPhase 2 GEM\, it
is recommended that they copy the folder "Sample Input Files - RELOCATE BEFORE USE"
from this default folder to a local folder. By doing so, users can easily run GEM and write output
results into the selected local folder and avoid potential administrative rights issues, since not all
organizations allow users to write files to C:\Program Files folders. Users can copy the sample
files folder to any convenient local folder and can rename it as needed once it is copied to its new
destination.
The agencies propose to require that vehicle manufacturers use the Phase 2 GEM
executable, which does not require the use of Matlab or Simulink software, for demonstrating
compliance with the proposed CO2 and fuel consumption standards. Phase 2 GEM does not offer
a graphical user interface (GUI) for users to provide their vehicle parameters. Instead, inputs are
provided in a .csv file. However, the agencies do provide a simple Microsoft Excel file with a
macro built in, allowing individual users or manufacturers to generate the necessary input file
and run GEM with one button-click. Results are available in a generated report that can be
viewed using either a text editor or spreadsheet. The following sections will describe the model,
its input files, and its output files in more detail.
Model Description
Phase 1 GEM was updated in order to meet proposed Phase 2 rulemaking requirements.
Phase 2 GEM improves the fidelity of the Phase 1 model to better match the function of the
simulated vehicles and accurately reflect changes in technology for compliance purposes. Many
of the modifications were the result of numerous constructive comments from both public
comments and GEM peer reviews1. The following sections describe the model with an emphasis
on the additional vehicle parameters available in the Phase 2 upgrade of the model. Users are
directed to Chapter 4 of the draft RIA for more detailed information regarding the model
architecture and validation.
GEM Architecture and Summary of Upgrades
The GEM architecture is comprised of four systems: Ambient, Driver, Powertrain, and
Vehicle as seen in Figure 11. The Powertrain and Vehicle systems consist of one or more
subcomponent models and a description of the subcomponent models is available in Chapter 4 of
the draft RIA.
11
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REVS VM Vehicle Model
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Figure 11: GEM model structure
The agencies are proposing additional regulatory subcategories to better represent the
heavy-duty vehicles and these subcategories are reflected in the model with additional vehicle
models. Phase 2 GEM also incorporates the proposed improvements to the duty cycles,
including the addition of an idle cycle for vocational vehicles, and modified cruise cycles that
account for changes in road grade. Specifically, the agencies are proposing to implement the
following key technical features into Phase 2 GEM:
• An upgraded engine controller, which includes engine fuel cut-off during braking and
deceleration
• An upgraded transmission model, which includes an upgraded manual transmission,
along with newly developed automatic and automated manual transmissions
• An upgraded driver model with a distance-compensated driver that will drive the
certification drive trace over a prescribed distance regardless of increased drive time due
to vehicle under-performance, for example
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With these upgrades, the model is capable of recognizing most technologies that could be
evaluated in both engine and chassis dynamometers and is better able to reflect changes in
technologies for compliance purposes. See Chapter 4 of the draft RIA for more information
about these upgrades.
GEM is a flexible simulation platform that can model a wide variety of vehicles with
conventional powertrains from Class 2b to Class 8. The key to this flexibility is the component
description files that can be modified or adjusted to accommodate vehicle-specific information.
Phase 2 GEM includes four main vehicle types, and several variations of each vehicle, to match
the regulatory subcategories in the proposed Phase 2 rulemaking. Each regulatory subcategory is
associated with specific vehicle parameters and technology options.
The agencies predefined many key parameters, since those parameters are either hard to
quantify due to lack of certified testing procedures or difficult to obtain due to proprietary
barriers. Examples of these parameters include transmission shifting strategies, transmission
gear mechanical efficiency, and transmission spin and pumping losses. The values selected for
these parameters are a result of substantial testing by EPA, as well as confidential discussions
with engine, chassis and component manufacturers.
Each vehicle subcategory has a set of user-defined parameters. These parameters include
vehicle technologies or component attributes that impact CO2 emissions and fuel consumption,
but have the potential to vary across manufacturers. Parameters such as aerodynamic
performance, vehicle weight, engine fuel map, transmission gear ratios, tire radius, or axle ratio
can all be changed as inputs by the user.
The sections to follow outline the regulatory vehicle subcategories that would use GEM
for compliance and summarizes the user-defined and predefined model parameters applicable to
each subcategory.
The proposed rulemaking also predefines three drive cycles including a transient cycle
and two cruise speed cycles. The transient mode is defined by California Air Resources Board
(CARB) in their Highway Heavy-Duty Diesel Transient (HHDDT) cycle. The cruise speed
cycles are represented by two constant speed 65 mph and 55 mph cycles, each with varying road
grade. A stationary "idle cycle" is also available to vocational vehicles, which evaluates both
zero torque and curb-idle transmission torque. Each regulatory subcategory is given a specific
set of drive cycle weightings.
The agencies recognize the limitation of the steady state engine fuel map for transient
simulation, and therefore are proposing a transient adjustment factor of 1.05 used only for
transient cycle. This means that the simulated transient cycle GEM results (that are generated
based on steady-state fuel maps) would be multiplied by 1.05 before being output from the GEM
compliance tool. The higher output value would be the official GEM result. The detailed
description and justification of this transient correction factor can be viewed in Chapter 4 of the
draft RIA.
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The agencies are proposing a set of predefined modeling parameters to establish
consistent combination tractor models from which tractor manufacturers can compare their
vehicle improvements. GEM recognizes nine variations of combination tractors. Class 8
tractors can have day or sleeper cab configurations with low, mid, or high roof heights. Class 7
tractors are only available in a day cab configuration, but also have low, mid, or high roof
options. Within GEM, high roof tractors are simulated as pulling a standard box trailer. Mid
roof tractors and low roof tractors are simulated as pulling tank and flatbed trailers, respectively.
The agencies are proposing that the standard box trailer for high roof tractor simulations also
include a skirt, which is represented by the user-defined aerodynamic drag area input, CdA
(described in the next section).
Table 1, Table 2, and Table 3 summarize the predefined modeling parameters for Class 8
sleeper cab, Class 8 day cab, and Class 7 tractors, respectively. All Class 8 tractors are modeled
with five axles in a 6x4 configuration with two steer tires and eight drive tires. The Class 8
payload is 19 tons. All Class 7 tractors are represented by a four axle tractor in a 4x2
configuration with two steer tires and four drive tires. The Class 7 payload is 12.5 tons. Sleeper
cab tractors are assigned drive cycle weightings that are more representative of long-haul driving
with 86 percent at 65-MPH, 9 percent at 55-MPH and 5 percent transient. Drive cycle
weightings for day cab tractors are more representative of short-haul driving with 64 percent at
65-MPH, 17 percent at 55-MPH, 19 percent transient.
Table 1 Class 8 Combination Tractor Sleeper Cab Predefined Modeling Parameters
Regulatory Subcategory
Roof Height
Total Weight (kg)
Number of Axles
Default Axle Configuration
Payload (tons)
CARB HHDDT Drive Cycle Weighting
GEM 55 mph Drive Cycle Weighting
GEM 65 mph Drive Cycle Weighting
Class 8 Combination, Sleeper Cab
High Roof Mid Roof
31978 30277
5
Low Roof
30390
6x4
19
0.05
0.09
0.86
Table 2 Class 8 Combination Tractor Day Cab Predefined Modeling Parameters
Regulatory Subcategory
Roof Height
Total Weight (kg)
Number of Axles
Default Axle Configuration
Payload (tons)
CARB HHDDT Drive Cycle Weighting
GEM 55 mph Drive Cycle Weighting
GEM 65 mph Drive Cycle Weighting
Class 8 Combination, Day Cab
High Roof Mid Roof
31297 29529
5
Low Roof
29710
6x4
19
0.19
0.17
0.64
Table 3 Class 7 Combination Tractor Predefined Modeling Parameters
| Regulatory Subcategory
I
Class 7 Combination, Day Cab
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Roof Height
Total Weight (kg)
Number of Axles
Default Axle Configuration
Payload (tons)
CARB HHDDT Drive Cycle Weighting
GEM 55 mph Drive Cycle Weighting
GEM 65 mph Drive Cycle Weighting
High Roof Mid Roof
22679 20910
4
Low Roof
21091
4x2
12.5
0.19
0.17
0.64
Table 4 shows the predefined modeling parameters that are consistent across all tractor
types. These common parameters include ambient temperature, efficiencies and accessory
powers. The calculations for overall rolling resistance and the distribution of weight savings are
also consistent for all modeled tractors.
Table 4 Common Predefined Modeling Parameters for All Simulated Combination Tractors
Gearbox Efficiency
Axle Mechanical Efficiency
Electrical Accessory Power (W)
Mechanical Accessory Power (W)
Environmental air temperature (°C)
Weight Reduction (Ibs)
Trailer Tire Crr (kg/t)
Overall Tire Crr (kg/t)
98% for 1 : 1 gear ratio, 96% for others
95.5%
300
1000
25
Add l/3*weight reduction to Payload tons
6.0
= 0.425*Trailer Crr + 0.425*Drive Crr + 0.15*Steer Crr
GEM allows a user to modify or adjust performance information for certain components
in order to model and quantify improvements the manufacturer is making to its vehicles. Table 5
lists the user-defined modeling parameters that are recognized in GEM. Phase 2 GEM continues
to allow tractor manufacturers to model their vehicle's tire rolling resistances, but also requires
each tire's loaded radius. Phase 2 GEM also continues to account for aerodynamic drag, but
manufacturers are asked to provide a wind-averaged aerodynamic drag area (CdA), instead of the
zero-yaw coefficient of drag (Cd) required in Phase 1. These updates were made in order to
more realistically model the rolling resistance and aerodynamic drag the vehicle would
experience in real world driving.
In Phase 1, a default engine and transmission were applied to all GEM-simulated
combination tractors. Phase 2 GEM requires manufacturers to supply an engine fuel map for
each distinct engine used in the modeled vehicles. Additionally, the manufacturer must include
specific transmission information to the model. The engine and the transmission information are
provided as separate input files with specific requirements, as will be discussed in the Input Files
section of this guide.
Table 5 User-Defined Modeling Parameters for Class 7 and Class 8 Combination Tractors (All Cabs and
Roof Heights)
Modeling Parameter
Steer Tire Crr (kg/t)
Method of Determining Parameter
ISO 28580:2009(E), See 40 CFR 1037.520(c)
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Drive Tire Crr (kg/t)
Tire Loaded Radius (m)
Aerodynamic Drag Area, CdA (m2)
Engine Fuel Map
Transmission
Drive Axle Ratio
See 40 CFR 1037.520(c)
See 40 CFR 1037.520(b) and 40 CFR 1037.525
From engine manufacturer or 40 CFR 1065.510
From transmission manufacturer: type, gear number, gear ratios
From axle manufacturer
Phase 2 GEM also accounts for additional technologies and vehicle configurations that
reduce CO2 and fuel consumption, but are not easily captured in the vehicle simulation. These
reduction values range from 0.5 percent to 2.5 percent and are applied internally to GEM after
the vehicle simulation has completed. Manufacturers would indicate if their vehicle includes any
of the technology improvements listed in Table 6 by indicating yes or no (Y or N in the input
file) and GEM would apply the appropriate emission reduction.
Table 6 Technology Improvement Options for Tractor Manufacturers
Technology Improvement
Vehicle Speed Limit
Weight Reduction (Ib)
Single Drive Axle (Class 8 Tractors Only)
Part Time Single Drive Axle (Class 8 Tractors Only)
Low Friction Axle Lubricant
Transmissions: AT, AMT, DCT
Predictive Cruise Control
High Efficiency A/C Compressor
Electric Engine Coolant and Power Steering Pumps
Automatic Tire Inflation System
Extended Idle Reduction (Sleeper Cabs Only)
Regulation Reference
See 40 CFR 1037.520(d)
See 40 CFR 1037.520(e)
See 40 CFR 1037.520(f)(l)
See 40 CFR 1037.520(f)(l)
See 40 CFR 1037.520(f)(2)
See 40 CFR 1037.520(f)(3)
See 40 CFR 1037.520(f)(4)
See 40 CFR 1037.520(f)(5)
See 40 CFR 1037.520(f)(6)
See 40 CFR 1037.520(f)(7)
See 40 CFR 1037.520(f)(8)
Reduction Value
Varies
Varies
2.5%
2.5%a
0.5%
2.0%
2.0%
0.5%
1.0%
1.0%
5.0%
Notes:
a Part Time Single Drive Axle reduction is 2.5% over the 55 mph and 65 mph cycles and zero over the CARD
HHDDT cycle
The agencies are proposing a set of predefined modeling parameters to establish
consistent vocational vehicle models from which manufacturers can compare their vehicle
improvements. GEM recognizes nine variations of vocational vehicles based on both vehicle
weight class and duty cycle. Class 8 vocational vehicles are considered heavy heavy-duty
(HHD). Classes 6 and 7 are medium heavy-duty (MHD), and Classes 2b-5 are considered light
heavy-duty (LHD). As seen in Table 7, Table 8, and Table 9, the weight, number of axles,
aerodynamic drag area and payload are the same for all of the vehicles within a weight class.
Vehicles within each weight class are further categorized using three duty cycles (Regional,
Multi-purpose and Urban) by varying the drive cycle weightings associated with each composite
duty cycle. The assignment of vocational vehicles to subcategories is described in the
regulations at 40 CFR 1037.510, and is based on a combination of vehicle attributes and
driveline parameters. The Multi-purpose cycle is the default for vocational vehicles unless the
16
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specified criteria indicate another cycle is more appropriate, or if the certifying manufacturer
requests placement in a different subcategory. GEM does not automatically pre-process
vocational vehicle inputs to assign vocational vehicles to subcategories, though GEM may be
used as a tool to assist in deciding how the criteria of 1037.510 apply to your vehicles. For
vocational vehicles with conventional powertrains and engines that are certified over both the
FTP and SET, manufacturers will generally need to know the following information in order to
decide whether the multi-purpose duty cycle is not the most appropriate for a vocational vehicle:
tire revs/mile, rear axle ratio, transmission gear ratios, maximum engine test speed, and primary
fuel type.
Table 7 Vocational HHD Vehicle Predefined Modeling Parameters
Regulatory Subcategory
Duty Cycle
Total weight (kg)
Number of Axles
CdA (m2)
Payload (tons)
ARE Transient Drive Cycle Weighting
GEM 55 mph Drive Cycle Weighting
GEM 65 mph Drive Cycle Weighting
Idle Cycle Weighting
HHD
Regional
Multi-Purpose
Urban
19051
3
6.86
7.50
0.50
0.28
0.22
0.10
0.82
0.15
0.03
0.15
0.94
0.06
0.00
0.20
Table 8 Vocational MHD Vehicle Predefined Modeling Parameters
Regulatory Subcategory
Duty Cycle
Total weight (kg)
Number of Axles
CdA (m2)
Payload (tons)
ARE Transient Drive Cycle Weighting
GEM 55 mph Drive Cycle Weighting
GEM 65 mph Drive Cycle Weighting
Idle Cycle Weighting
MHD
Regional
MHD
Multi-Purpose
MHD
Urban
11408
2
5.40
5.60
0.50
0.28
0.22
0.10
0.82
0.15
0.03
0.15
0.94
0.06
0.00
0.20
Table 9 Vocational LHD Vehicle Predefined Modeling Parameters
Regulatory Subcategory
Duty Cycle
Total weight (kg)
Number of Axles
CdA (m2)
Payload (tons)
ARE Transient Drive Cycle Weighting
GEM 55 mph Drive Cycle Weighting
GEM 65 mph Drive Cycle Weighting
Idle Cycle Weighting
LHD
Regional
LHD
Multi-Purpose
LHD
Urban
7257
2
5.40
2.85
0.50
0.28
0.22
0.10
0.82
0.15
0.03
0.15
0.94
0.06
0.00
0.20
17
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Table 10 shows the predefined modeling parameters that are consistent across all
vocational vehicle types. These common parameters include ambient temperature, efficiencies
and accessory powers. It should be noted that GEM will assign all automated manual or dual
clutch transmissions a 98 percent efficiency for the gear with a 1:1 ratio and 96 percent
efficiency for all others. All gears in an automatic transmission are assumed to have a 98 percent
efficiency (pump losses and spin losses are accounted for separately from the gear losses for
automatic transmissions). The calculations for overall rolling resistance and the distribution of
weight savings are also consistent for all modeled vocational vehicles.
Table 10 Common Predefined Modeling Parameters for All Vocational Vehicles
Gearbox Efficiency for AMT
Gearbox Efficiency for AT
Axle Mechanical Efficiency
Electrical Accessory Power (W)
Mechanical Accessory Power (W)
Environmental Air Temperature (°C degree)
Weight Reduction (Ibs)
Overall Tire Crr (kg/t)
98% for 1 : 1 gear ratio, and 96% for others
98% for all gears
95.5%
300
1000
25
Add 0.5*weight reduction to Payload tons
= 0.7*Drive Crr + 0.3*Steer Crr
GEM allows a user to modify or adjust performance information for certain components
in order to model and quantify improvements the manufacturer is making to its vehicles. Table
11 lists the user-defined modeling parameters that are recognized in GEM for vocational
vehicles. In Phase 1 GEM, vocational vehicle manufacturers were only given the option of
changing the rolling resistance of their steer and drive tires. Phase 2 GEM continues to allow
vocational vehicle manufacturers to model their vehicle's tire rolling resistances, but also
requires each tire's loaded radius. Additionally, Phase 2 GEM requires manufacturers to supply
an engine fuel map and specific transmission information to for each distinct engine and
transmission in the vehicles being modeled. The engine and the transmission information are
provided as separate input files with specific requirements, as will be discussed in the Input Files
section of this guide. Note that emergency vehicles are only allowed to adopt lower rolling
resistance tires on their steer and drive tires in this proposal. The rest of the parameters do not
apply to emergency vehicles.
Table 11 User-Defined Modeling Parameters for Vocational Vehicles (All Weight Classes)
Modeling Parameter
Steer Tire Crr (kg/t)
Drive Tire Crr (kg/t)
Tire Loaded Radius (m)
Engine Fuel Map
Transmission
Drive Axle Ratio
Method of Determining Parameter
ISO 28580:2009(E), See 40 CFR 1037.520(c)
See 40 CFR 1037.520(c)
From engine manufacturer or 40 CFR 1065.510
From transmission manufacturer: type, gear number, gear ratios
From axle manufacturer
18
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As is proposed for the tractor model, Phase 2 GEM accounts for additional vocational
vehicle technologies that reduce CO2 and fuel consumption, but are not easily captured in the
vehicle simulation. These reduction values range from 0.5 percent to 2.5 percent and are applied
internally to GEM after the vehicle simulation has completed. Manufacturers would indicate if
their vehicle includes any of the technology improvements listed in Table 12 by indicating yes or
no (Y or N in the input file) and GEM would apply the appropriate emission reduction.
Table 12 Technology Improvement Options for Vocational Vehicle Manufacturers
Technology Improvement
Weight Reduction (Ib)
Power Take Off (g/ton-mile)
HHD Single Drive Axle (6x2) Configuration
HHD Part-time Single Drive Axle 6x2 Configuration
Low Friction Axle Lubricant
Transmissions: AMT, DCT (HHD, Regional Only)
Idle Reduction: Start-Stop
Idle Reduction: Neutral Idle
Regulation Reference
See 40 CFR 1037.520(e)
See 40 CFR 1037.540
See 40 CFR 1037.520(f)(l)
See 40 CFR 1037.520(f)(l)
See 40 CFR 1037.520(f)(2)
See 40 CFR 1037.520(f)(3)
See 40 CFR 1037.520(f)(8)
See 40 CFR 1037.520(f)(8)
Reduction Value
Varies
Varies
2.5%
0.1%-1.0%a
0.5%
2.3%
Determined by idle
fuel map
Notes:
a Based on 2.5% over the 55 mph and 65 mph cycles and zero over the CARD HHDDT cycle
The agencies are proposing an equation-based compliance approach for box trailer
manufacturers and they are not required to certify their trailers using GEM. However, the
equations for each box trailer subcategory are based on the simulated trailers described in this
section. Note that non-box trailers do not use GEM or the GEM-based equation for compliance
and a discussion of non-box trailers is not included in this user guide. The following description
of the trailer model as it applies to box trailers is included for informational purposes only.
The agencies are proposing a set of predefined modeling parameters to establish
consistent tractor-trailer models from which box van trailer manufacturers can compare their
vehicle improvements. GEM recognizes four variations of box van based on length. All
simulated box vans are modeled as a combination tractor-trailer with a Class 8 high roof tractor.
Long box vans (trailers that are longer than 50-feet) are represented by either a 53-foot dry van
or a 53-foot refrigerated van in GEM. The tractor-trailer model for long-box vans includes a
sleeper cab tractor and is given the same long-haul drive cycle weightings as the Class 8 high
roof sleeper cab tractors mentioned previously. GEM models all short box vans (box trailers 50-
feet in length and shorter) as a single-axle, solo 28-foot dry van or refrigerated van.
Table 13 and Table 14 summarize the predefined modeling parameters for long and short
box vans, respectively. All long box vans are modeled with tandem axles and a payload of 19
tons and drive cycle weightings that are more representative of long-haul driving (i.e., 86 percent
at 65-MPH, 9 percent at 55-MPH and 5 percent transient). All short box vans are modeled with
a single axle, a payload of 10 tons, and drive cycle weightings more representative of short-haul
driving with 64 percent at 65-MPH, 17 percent at 55-MPH, 19 percent transient. The vehicle
weight varies between dry vans and refrigerated vans to account for the weight of the
19
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refrigeration unit, and weight also varies proportional to the length of the trailer. The baseline
CdA values were obtained from EPA's aerodynamic testing.
Table 13 Predefined Modeling Parameters for Long Box Trailers
Regulatory Subcategory
Tractor Type
Total weight (kg)
Baseline CdA Values (m2)
Number of Axles
Payload (tons)
CARB HHDDT Drive Cycle Weighting
GEM 55 mph Drive Cycle Weighting
GEM 65 mph Drive Cycle Weighting
Long Box
Dry Van
Long Box
Refrigerated Van
C8 Sleeper Cab - High Roof
31978
6.2
33778
6.1
5
19
0.05
0.09
0.86
Table 14 Predefined Modeling Parameters for Short Box Trailers
Regulatory Subcategory
Tractor Type
Total weight (kg)
Baseline CdA Values (m2)
Number of Axles
Payload (tons)
ARE Transient Drive Cycle Weighting
GEM 55 mph Drive Cycle Weighting
GEM 65 mph Drive Cycle Weighting
Short Box
Dry Van
Short Box
Refrigerated Van
C8 Day Cab -High Roof
15191
6.1
16991
6.0
4
10
0.19
0.17
0.64
Table 15 shows the predefined modeling parameters that are consistent across all trailer
types. Many of these common parameters are associated with the simulated tractor in the tractor-
trailer model. The calculations for overall rolling resistance and the distribution of weight
savings are consistent with the calculations for GEM-simulated tractors.
Table 15 Common Predefined Modeling Parameters for All Box Trailers
Engine Fuel Map
Gear ratio
Gearbox Efficiency
Axle Drive Ratio
Axle Mechanical Efficiency
Default Tractor Axle Configuration
Electrical Accessory Power (W)
Mechanical Accessory Power (W)
Tire Radius (m)
Steer Tire Crr (kg/t)
Drive Tire Crr (kg/t)
Overall Tire Crr (kg/t)
Weight Reduction (Ibs)
15L - 455 HP
12.8, 9.25, 6.76, 4.9, 3.58, 2.61, 1.89, 1.38, 1, 0.7:
98% for 1 : 1 gear ratio, and 96 for all other gears
3.7
95.5%
6x4
300
1000
0.5
6.54
6.92
= 0.425*Trailer Crr + 0.425*Drive Crr + 0. 15*Steer
Add l/3*weight reduction to Payload tons
5
Crr
20
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GEM allows a user to modify or adjust performance information for certain components
in order to model and quantify improvements the manufacturer is making to its vehicles. The
trailer program has three user-defined parameters and one pre-defined technology improvement
option that has a specified reduction value associated with its use (see Table 16). Trailer
manufacturers are able to change their tire rolling resistance, aerodynamic drag and cumulative
weight reduction. GEM applies an additional technology improvement value of 1.5 percent for
manufacturers that indicate they installed automatic tire inflation systems on their simulated
trailer.
Table 16 User-Defined Modeling Parameters and Technology Improvement Options for Trailers (All
Lengths)
Modeling Parameter
Trailer Tire Crr (kg/t)
Change in Aerodynamic Drag Area, ACdA (m2)
Weight Reduction (Ib)
Automatic Tire Inflation System
Method of Determining Parameter
ISO 28580:2009(E), See 40 CFR 1037.5 15(b)
See 40 CFR 1037.5 15(c) and 40 CFR 1037.525
See 40 CFR 1037.5 15(d)
1.5% if applied, See 40 CFR 1037.515(a)
GEM Input File Structure
As mentioned previously, Phase 2 GEM does not offer a graphical user interface (GUI)
for users to provide their vehicle parameters. Instead, inputs are exclusively provided to the
model in a .csv file. Phase 2 GEM can be executed using either of two methods. The standard
method directly initiates the model by running the executable file. Inputs for the standard
method are provided as .csv files. The second method requires use of Microsoft Excel. Users
generate an .xlsm input file using the template provided for their given vehicle subcategory and
initiate the model by clicking the "RUN GEM" button within the spreadsheet. The button
prompts a macro to generate the appropriate .csv file from the spreadsheet provided, and runs the
executable. Additionally, the Excel spreadsheet features a "Validate" button which will check
the input file for errors without running the executable. All methods provide their results in a
.csv output file and an error log .txt file.
Some manufacturers that choose the standard method of running Phase 2 GEM may
create a script to automatically generate their input files in .csv format. Others may wish to
manually populate their files using a spreadsheet tool, such as Microsoft Excel, to easily view the
input fields in a column format, and save the files in a .csv format. Some manufacturers may opt
for the Excel-based method of generating inputs and creating the .csv input files through a
macro. The following subsections describe the input file structures, which are consistent for
each method of running the model. For illustration purposes, the .csv input files in this section
are shown in spreadsheet format. The following section, Running GEM, describes the options
for running the model.
21
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Note to Users Creating or Editing .csv Files Using Microsoft Excel
Users may use Microsoft Excel or any other text editor, such as Notepad, to create or edit
their input files. Once a file is created, it can be saved by going to go to "Save As..." and choose
CSV (Comma delimited) (*.csv) in the "Save as type:" pull-down menu, as shown in Figure 12.
In future saves, or when editing and resaving an existing .csv formatted file, users may receive a
warning similar to Figure 13. Select "Yes" to ensure the file is properly saved in .csv format.
mm
k^. i. > GEM Input Files > Tractor
Organizes New folder
QE Microsoft Excel
Vf Favorites
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'_ Name
61] EPA_Sampfe_Engine_350hp
JS EPA_Samp!e_Engine_455hp
t; EPA_Sample_Trans_AMT
8il EPA_Ssmplt_Trans_MT
tii] GEM.Sample_TRACTOR
?5j GEM_Sample_TRACTOR.Csv_r...
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Date modified Type Size
4W2015 U:50 AM Mi osoft Excel Comma Separated Values F... 36KB
4«/2015 11:50 AM Mi osoft Excel Comma Separated Values F... 36KB
4/8/2015 12:53 PM Mi osoft Excel Comma Separated Values F... 1 KB
5/13/2015 11:38 AM Mi osoft Excel Comma Separated Values F... 1KB
5/19/2015 9:14 AM Mi osoft Excel Comma Separated Values F... 2KB
5/19/2015 9:10 AM Mi osoft Excel Comma Separated Values F... 2KB
Filename: Ne^vFileName T
Save as type: CS1
(Comma delimited]
-
Excel Workbook
"": Excel Macro-Enabled Workbook
Excel Binary Workbook
Excel 97-2003 Workbook
* Hide Folders XML Data
Single File Web Page
Figure 12: Example "Save As..." Window to Create a Comma Separated Value (.csv) Input File
Microsoft Excel
Some features in your workbook might be lost if you save it as CSV (Comma delimited),
Do you want to keep using that format?
Help
Figure 13: Warning from Microsoft Excel When Saving .csv Files Using Excel - Select "Yes"
Tractor Input Files
The top of the tractor input file has three lines that list the regulatory category,
manufacturer name and model year (see Figure 14). Users complete the second column for each
line. The first line must read "Tractor" in order for GEM to run the appropriate vehicle model.
Manufacturer name can be in any format, but it should be consistent with other regulatory
documents from the manufacturer. Model year should be expressed as a four-digit number.
22
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Regulatory Category Tractor
Manufacturer Name
Model Year
Figure 14: Tractor Input File Header Information
The next lines of the tractor input file contain the model inputs. In the first two columns,
shown in Figure 15, the user provides a Run ID and the Regulatory Subcategory for each run.
The Run ID is a unique value that will be used to identify the run (e.g., vehicle VEST). It can be
any combination of letters, numbers and separators such as dash ("-"), periods ("."), or
underscores ("_")• The Regulatory Subcategory determines which standard is applied for
compliance. For tractors, there are 10 regulatory subcategories in GEM and Table 17 shows the
naming convention.
Run ID
Unique Identifier
TRAC1
TRAC2
TRAC3
TRAC4
TRAC_PT1
TRAC_PT2
TRAC PT3
Regulatory Subcategory
(e.g. C8_SC_HR)
C8_SC_HR
C7_DC_HR
C8_DC_LR
C8_HH
C8_SC_MR
C8_DC_MR
C7 DC HR
Figure 15: Tractor Input File Run ID and Regulatory Subcategory Inputs
Table 17: Tractor Input File Naming Convention for Tractor Regulatory Subcategories
GEM Input Name
C8 SC HR
C8 SC MR
C8 SC LR
C8 DC HR
C8 DC MR
C8 DC LR
C8 HH
C7 DC HR
C7 DC MR
C7 DC LR
Regulatory Subcategory Description
Class 8 Combination, Sleeper Cab - High Roof
Class 8 Combination, Sleeper Cab - Mid Roof
Class 8 Combination, Sleeper Cab - Low Roof
Class 8 Combination, Day Cab - High Roof
Class 8 Combination, Day Cab - Mid Roof
Class 8 Combination, Day Cab - Low Roof
Class 8 Combination, Sleeper Cab - Heavy Haul
Class 7 Combination, Day Cab - High Roof
Class 7 Combination, Day Cab - Mid Roof
Class 7 Combination, Day Cab - Low Roof
The next columns contain the tractor performance parameters and several vehicle
characteristics that are user-defined in GEM. A description of these parameters was given in
Table 5 and additional information is available preamble to the proposed Phase 2 rulemaking.
23
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Aerodynamic Tire Steer Axle Tire Drive Axle Tire Drive Axle
Aerodynamic Drag Area (CdA) Loaded Tire Radius Coefficient of Rolling Resistance Level Coefficient of Rolling Resistance Level Ratio
m*2
6.2
6.4
5.3
NA
5.9
5.8
6.1
0.5
0.5
0.47
0.5
0.5
0.5
0.5
kg/t
6.5
6.9
6.8
6.5
6.5
6.2
4.8
kg/t
6.9
7.3
6.9
6.9
6.9
6.3
5.1
Figure 16: Tractor Input File Performance Parameters and User-Defined Vehicle Characteristics
3.7
3.7
3.82
3.7
3.37
3.7
2.95
There are limits associated with each user-defined input value. Table 18 shows the limits
for the five tractor inputs in the model. GEM will produce an error if any of these values are out
of the acceptable range.
Table 18: Minimum and Maximum Limits for User-Defined Values in Tractor Input File
User-Defined Parameter
Aerodynamic Drag Area (CdA)
Tire Radius
Steer Axle Tire, Crr
Drive Axle Tire, Crr
Drive Axle Ratio
Units
mA2
m
kg/t
kg/t
#
Minimum
Value
4.1
0.3
4.0
4.2
1.8
Maximum
Value
7.6
0.6
8.1
8.5
10
The next columns in the input file are for the engine and transmission file names or the
powertrain file name. A description of the content of these supplemental input files is located at
the end of this section. The text in the fields of the input file must exactly match the file name,
including the .csv extension for the code to run properly. In Figure 17, these supplemental files
are located in the same folder as the tractor input file. As a result, only the file name is needed.
Manufacturers may choose to perform powertrain testing to obtain the engine and
transmission performance for their GEM simulations. In order to indicate to GEM that
powertrain data is provided, users would provide the same powertrain input file name in both the
Engine and Transmission file name fields of the tractor input file, as seen in the last three rows of
Figure 17
Engine
Data
File Name
EPA_Sample_455hp.csv
EPA_Sample_350hp.csv
EPA_Sample_455hp.csv
EPA_Sample_455hp.csv
EPA_Sample_PT.csv
EPA_Sample_PT.csv
EPA_Sample_PT.csv
Transmission
Data
File Name
EPA_Sample_AMT.csv
EPA_Sample_AMT.csv
EPA_Sample_MT.csv
E P A_S a m pi e_AMT. c sv
EPA_Sample_PT.csv
EPA_Sample_PT.csv
EPA_Sample_PT.csv
Figure 17: Tractor Input File Reference to Engine, Transmission, and Powertrain Input Files
24
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Users can also save their engine, transmission, and powertrain input files in separate
folders within the same folder as the main vehicle input file, as shown in Figure 18. At this time,
the model is not able to reference folders for the supplemental input files located outside of the
vehicle input file's directory.
£J^t yv > GEM Sample Input Files > Tractor > ~ Vy | | ;--jr-:,- -._7_::. p
File Edit View lools Help
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£ Downloads
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! j Documents
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Burn New folder 1= ' BJ ®
Name Date modified Type Size
3EngineInputs 6/2/2015 1:19 PM File folder
Powertrainlnputi 6/2/2015 1:20 PM Filefolder
. . Transmissionlnput! 6/2/2015 1:19 PM Rle folder
|lUGEM_TRACTOR.csv 5/29/2015 3:42 PM Microsoft Excel C... 2KB]
(SB GEMJ-RACTORxIsm 5/29/2015 4:18 PM Microsoft Excel M... 31KB
fj GEM_TRACTOR.xlsm.orig 5/29/2015 4:18 PM ORIG File 31 KB
,_, GEM_TRACTOR_errors.txt 6/2/20158:52 AM Text Document 1KB
jii GEM_TRACTOR_result.csv 6/2/2015 8:52 AM Microsoft Excel C... 3KB
8 items
Figure 18: Option to Save Engine, Powertrain, and Transmission Input Files in Separate Folders
If the supplemental input files are located in the folders shown in Figure 18, the text in
the Engine and Transmission fields of the input file would match the text in Figure 19.
Engine
Data
File Name
Enginelnputs''.EPA_Sample_455hp.csv
Enginelnputs\EPA_Sample_350hp-Csv
Enginelnputs\EPA_Sample_455hp.csv
Enginelnputs\EPA_Sample_455hp.csv
Powertrainlnputs\EPA_Sample_PT.csv
Powertrainlnputs\EPA_Sample_PT-Csv
Powertrainlnputs'iEPA_Sample_PT.csv
Transmission
Data
File Name
Transmissionlnputs\EPA_Sample_AP»1T.csv
Transmissionlnputs\EPA_Sample_AMT.csv
Transmissionlnputs\EPA_Sample_MT.csv
Transmissionlnputs\EPA_Sample_AMT.csv
Powertrainlnputs\EPA_Sample_PT-Csv
Powertrainlnputs\EPA_Sample_PT.csv
Powertrainlnputs\EPA_Sample_PT.csv
Figure 19: Tractor Input File Reference to Engine, Transmission, and Powertrain Input Files When Files are
Located in Separate Folders
The next columns in the tractor input file are for the optional technology improvements.
These technology improvements were summarized in Table 6. These technology improvement
fields cannot be blank in the input file. Users that wish to model their vehicle with weight
reduction can enter the cumulative weight reduction value (0 to 10,000 Ibs or "NA") in the first
field. The use of a speed limiter is modeled by inserting the speed limit value. Note that GEM
does not provide a benefit for speed limiters set above 65 mph. Vehicles without a speed limiter
would use the value "NA". The remaining technology improvements are Boolean values ("Y"
25
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for yes, "N" for no). By default, these inputs are set to "N". Note that the Single Drive Axle
improvement is only available to Class 8 tractors, since Class 7 tractors are only modeled with a
single-drive axle, and that Idle Reduction with APU is only available to the Class 8 sleeper cab
tractors. Also note that these inputs are case-sensitive. All values of "Y", "N", or "NA" must be
in UPPERCASE LETTERS. Lowercase letters will produce an error.
Table 19: Summary of Technology Improvements in Tractor Input File
Technology Improvement
Weight Reduction
Speed Limiter
Single Drive Axle (applies to Class 8 only)
Part Time Single Drive Axle (applies to Class 8 only)
Low Friction Axle Lubricant
Predictive Cruise Control
High Efficiency A/C Compressor
Electric Accessories
Extended Idle Reduction (Class 8 sleeper cab tractors only)
Automatic Tire Inflation System
Units
Ibs
MPH
Y/N
Y/N
Y/N
Y/N
Y/N
Y/N
Y/N
Y/N
Range
Oto 10,000 or "NA"
0 to 65 or "NA"
Must be "Y" or "N", not blank
Must be "Y" or "N", not blank
Must be "Y" or "N", not blank
Must be "Y" or "N", not blank
Must be "Y" or "N", not blank
Must be "Y" or "N", not blank
Must be "Y" or "N", not blank
Must be "Y" or "N", not blank
Users may note that Table 19 does not include the technology improvement input from
automated transmissions as indicated from Chapter 4 of the draft RIA. This is because GEM is
designed in such a way that once users select automated manual, dual clutch or automatic
transmission in the transmission input .csv file, the technology improvement input is
automatically added into the post processor to get benefits.
The top of the vocational input file has three lines that list the regulatory category,
manufacturer name and model year (see Figure 20). The first line must read "Vocational" in
order for GEM to run the appropriate vehicle model. Manufacturer name can be in any format,
but it should be consistent with other regulatory documents from the manufacturer. Model year
should be expressed as a four-digit number.
Regulator/ Category Vocational
Manufacturer Name
Model Year
Figure 20: Vocational Input File Header Information
The next lines of the vocational input file contain the model inputs. In the first two
columns, shown in Figure 21, the user provides a Run ID and the Regulatory Subcategory for
each run. The Run ID is a unique value that will be used to identify the run (e.g., vehicle VEST).
It can be any combination of letters, numbers and separators such as dash ("-"), periods ("."), or
underscores ("_")• The Regulatory Subcategory determines which standard is applied for
26
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compliance. For vocational, there are 12 regulatory subcategories in GEM and Table 20 shows
the naming convention.
Run ID
Unique Identifier
VOC1
VOC2
VOC3
VOC4
VOC5
VOC_PT1
VOC_PT2
VOC PT3
Regulatory Subcategory
(e.g HHD_R)
HHD_R
HHD_M
MHD_R
LHD_U
MHD_E
MHD_M
MHDJJ
LHD M
Figure 21: Vocational Input File Run ID and Regulatory Subcategory Inputs
Table 20: Vocational Input File Naming Convention for Vocational Regulatory Subcategories
GEM Input Name
HHD R
HHD M
HHD U
MHD R
MHD M
MHD U
LHD R
LHD M
LHD U
HHD E
MHD E
LHD E
Regulatory Subcategory Description
Heavy -Heavy Duty, Regional
Heavy -Heavy Duty, Multipurpose
Heavy -Heavy Duty, Urban
Medium-Heavy Duty, Regional
Medium-Heavy Duty, Multipurpose
Medium-Heavy Duty, Urban
Light-Heavy Duty, Regional
Light-Heavy Duty, Multipurpose
Light-Heavy Duty, Urban
Heavy -Heavy Duty, Emergency
Medium-Heavy Duty, Emergency
Light-Heavy Duty, Emergency
The next columns contain the vocational performance parameters and vehicle
characteristics that are user-defined in GEM. A description of these parameters was given in
Table 12 and additional information is available in the preamble to the proposed Phase 2
rulemaking.
Tire Steer Axle Tire Drive Axle Tire Drive Axle
Loaded Tire Radius Coefficient of Rolling Resistance Level Coefficient of Rolling Resistance Level Ratio
m kg/t kg/t #
0.48
0.48
0.46
0.38
NA
0.48
0.48
0.48
7.7
7.7
7.7
7.7
7.7
6.5
7.1
7.1
7.7
7.7
7.7
7.7
7.7
6.8
7.5
7.5
3.76
4.33
4.33
4.1
NA
4.33
4.33
4.33
Figure 22: Vocational Input File Performance Parameters and User-Defined Vehicle Characteristics
27
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There are limits associated with each user-defined input value. Table 21 shows the limits
for the four vocational inputs in the model. GEM will produce an error if any of these values are
out of the acceptable range.
Table 21: Minimum and Maximum Limits for User-Defined Values in Vocational Input File
User-Defined Parameter
Tire Radius
Steer Axle Tire Crr
Drive Axle Tire Crr
Drive Axle Ratio
Units
m
kg/t
kg/t
none
Minimum
Value
0.2
4.0
4.0
1.8
Maximum
Value
0.7
12.0
12.0
12.0
The next columns in the input file are for the engine and transmission file names or the
powertrain file name. A description of the content of these supplemental input files is located at
the end of this section. The text in the fields of the input file must exactly match the file name,
including the .csv extension for the code to run properly. In Figure 23, these engine or
transmission files are located in the same folder as the vocational input file. As a result, only the
file name is needed.
Manufacturers may choose to perform powertrain testing to obtain the engine and
transmission performance for their GEM simulations. In order to indicate to GEM that
powertrain data is provided, users would provide the same powertrain input file name in both the
Engine and Transmission file name fields of the tractor input file, as seen in the last three
columns of Figure 23.
Engine Transmission
Data Data
File Name File Name
EPA_Sample_455hp.csv EPA_Sample_MT_10_HHD.csv
EPA_Sample_345hp,csv EPA_Sample_AT_5_HHD,csv
EPA_Sample_270hp.csv EPA_Sample_AT_5_MLHD.csv
EPA_Sample_200hp.csv EPA_Sample_AT_5_MLHD.csv
NA NA
EPA_Sarnple_PT.csv EPA_Sample_PT.csv
EPA_Sample_PT.csv EPA_Sample_PT.csv
EPA_Sample_PT.csv EPA_Sample_PT.csv
Figure 23: Vocational Input File Reference to Engine, Transmission, and Powertrain Input Files
Users can also save their engine, transmission, and powertrain input files in separate
folders within the same folder as the main vehicle input file, as shown in Figure 24.
28
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File Edit View look Help
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Name
i. Enginelnputs
Powertrainlnputs
Transmissionlnputs
Date modified
Type
6/2/2015 2:02 PM File folder
6/2/2015 2:02 PM File folder
6/2/2015 2:02 PM File folder
0 GEM.VOCATIONAL.C!
5/29-2015 8:43 AM
1 :
7 GEM VOCATIONALxIsr
6A/2015 12:54 PM
Figure 24: Option to Save Engine, Powertrain, and Transmission Input Files in Separate Folders
If the supplemental input files are located in the folders shown in Figure 24, the text in
the Engine and Transmission fields of the vocational input file would match the text in Figure
25. Note that the fifth row contains "NA" for both the engine and transmission file names, since
the vehicle modeled in the sample file is an emergency vehicle.
Engine
Data
File Name
Enginelnputs\EPA_Sample_455hp.csv
Enginelnputs\EPA_Sample_345hp-Csv
Engmelnputs\EPA_Sample_270hp.csv
Engmelnputs\EPA_Sample_200hp.csv
NA
Powertrainlnputs\EPA_Sample_PT.csv
Powertrainlnputs\EPA_Sample_PTcsv
Powertrainlnputs\EPA_Sample_PT-Csv
Transmission
Data
File Name
Transmissionlnputs\EPA_Sample_MT_10_HHD.csv
Transmissionlnputs''.EPA_Sample_AT_5_HHD-Csv
Transmissionlnputs\EPA_Sample_AT_5_MLHD.csv
Transmissionlnputs\EPA_Sample_AT_5_MLHD.csv
NA
Powertrainlnputs\EPA_Sample_PT_csv
Powertrainlnpirts\EPA_Sample_PT.csv
Powertrainlnputs\EPA_Sample_PT-Csv
Figure 25: Vocational Input File Reference to Engine, Transmission, and Powertrain Input Files When Files
are Located in Separate Folders
The next columns in the vocational input file are for the optional technology
improvements. These technology improvements were summarized in Table 11. These
technology improvement fields cannot be blank in the input file. Users that wish to model their
vehicle with weight reduction can enter the cumulative weight reduction value (0 to 10,000 Ibs or
"NA") in the first field. The remaining technology improvements are Boolean values ("Y" for
yes, "N" for no). By default, these inputs are set to "N". Note that the Single Drive Axle
improvement (also known as axle disconnect) is only available to Heavy Heavy-Duty Regional
vehicles. If selected for other vocational subcategories, the input will produce an error. Also,
note that the stop-start and neutral idle technologies are mutually exclusive and users will receive
an error if both technology options are selected for the same vehicle. If the vocational vehicle
will be built with a hybrid PTO and testing was conducted according to 40 CFR 1037.540, then
the Delta PTO value obtained from that test procedure may be entered. Also note that these
29
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inputs are case-sensitive. All values of "Y", "N", or "NA" must be in UPPERCASE LETTERS.
Lowercase letters will produce an error.
Table 22: Summary of Technology Improvements in Vocational Input File
Technology Improvement
Delta PTO Fuel
Weight Reduction
Single Drive Axle (applies to HHD only)
Part Time Single Drive Axle (applies to HHD only)
Low Friction Axle Lubricant
Neutral-Idle
Stop-Start
g/ton-mile
Ibs
Y/N
Y/N
Y/N
Y/N
Y/N
0 ... 30or"NA"
0 ... 10,000 or "NA"
Must be "Y" or "N", not blank
Must be "Y" or "N", not blank
Must be "Y" or "N", not blank
Must be "Y" or "N", not blank
Must be "Y" or "N", not blank
Similar to tractors, Table 22 does not include the technology improvement inputs for
automated transmissions for HHD Regional vehicles, once users select an automated manual or
dual clutch transmission in the transmission input .csv file for HHD Regional vehicles, the
technology improvement input is automatically added into the post processor to get benefits. For
all subcategories, GEM simulates DCT as AMT.
The top of the trailer input file has three lines that list the regulatory category,
manufacturer name and model year (see Figure 26). The first line must read "Trailer" in order
for GEM to run the appropriate vehicle model. Manufacturer name can be in any format, but it
should be consistent with other regulatory documents from the manufacturer. Model year should
be expressed as a four-digit number.
Regulatory Category Trailer
Manufacturer Name
Model Year
Figure 26: Trailer Input File Header Information
The next lines of the trailer input file contain the model inputs. In the first two columns,
shown in Figure 27, the user provides a Run ID and the Regulatory Subcategory for each run.
The Run ID is a unique value that will be used to identify the run. It can be any combination of
letters, numbers and separators such as dash ("-"), periods ("."), or underscores ("_")• The
Regulatory Subcategory determines which standard is applied for compliance. For trailers, there
are four regulatory subcategories modeled in GEM and Table 23 shows the naming convention.
30
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Run ID
Unique Identifier
TRL1
TRL2
TRL3
Regulatory Subcategory
(e.g. LDV)
LDV
LRV
SDV
Figure 27: Trailer Input File Run ID and Regulatory Subcategory Inputs
Table 23: Trailer Input File Naming Convention for Trailer Regulatory Subcategory Inputs
GEM Input Name
LDV
LRV
SDV
SRV
Regulatory Subcategory Description
Long Dry Van
Long Refrigerated Van
Short Dry Van
Short Refrigerated Van
The next columns contain the trailer performance parameters and technology
improvement options that are user-defined in GEM. A description of these parameters was given
in Table 16 and additional information is available preamble to the proposed Phase 2
rulemaking. Note that the aerodynamic improvement for trailers is measured as a delta CdA and
not the absolute CdA value used in the proposed tractor program.
Aerodynamic Improvement (Delta) Trailer Tire Technology Improvement Technology Improvement
Aerodynamic Drag Area (CdA) Coefficient of Rolling Resistance Level Weight Reduction Automatic Tire Inflation System
m*2 kg/t Ibs Y/N
0.3 5.6 600 Y
0.1 6.3 0 N
0.4 6 150 N
Figure 28: Trailer Input File Performance Parameters and User-Defined Vehicle Characteristics
There are limits associated with each user-defined input value. Table 21 shows the limits
for the two trailer inputs in the model. GEM will produce an error if any of these values are out
of the acceptable range.
Table 24: Minimum and Maximum Limits for User-Defined Values in Trailer Input File
User-Defined Parameter
Aerodynamic Drag Area (CdA)
Tire Rolling Resistance Level (TRRL)
Units
mA2
kg/t
Minimum
Value
0
3
Maximum
Value
2
7
The technology improvement fields cannot be blank in the input file. Users that wish to
model their vehicle with weight reduction can enter the cumulative weight reduction value (0 to
10,000 Ibs or "NA") in the first field. The automatic tire inflation input is a Boolean ("Y" for
yes, "N" for no). By default, this inputs is set to "N". Note that these inputs are case-sensitive.
31
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All values of "Y", "N", or "NA" must be in UPPERCASE LETTERS. Lowercase letters will
produce an error.
Table 25: Summary of Technology Improvements in Trailer Input File
Technology Improvement
Weight Reduction
Automatic Tire Inflation System
Units
Ibs
none
Range
Oto 10,000 or "NA"
Must be "Y" or "N", not blank
Tractor and vocational vehicle manufacturers are required to generate either separate
engine and transmission input files, or a single powertrain input file for GEM. These files must
be in .csv format to be properly read by the model. The GEM installation file includes a
template for these supplemental input files. A vehicle manufacturer would generate a separate
engine and transmission file for each engine and transmission used in its vehicles or separate
powertrain files for each engine and transmission combination tested. We recommend that the
manufacturers choose a consistent naming convention that provides unique file names for these
input files. An example naming convention for each file type is provided in Table 26. However,
manufacturers are free to choose their own naming convention for all of their input files.
Table 26 Example Naming Convention for GEM Input Files
Input File Type
Engine
Transmission
Powertrain
Example Naming Convention
MfrName FuelType ModelYear ModelName CalibrationlD.csv
MfrName_TransType_Gears_ModelName_CalibrationID . csv
MfrName EngineName TransName ModelYear CalibrationlD.csv
The first row of the GEM input file for engines shows the GEM version, and
manufacturers would fill in the fourth row with the Manufacturer Name, Combustion Type, Fuel
Type, Family Name, and Calibration ID, as shown in Figure 29. The manufacturer can choose
any Manufacturer Name, Family Name and Calibration ID, but the names should be consistent
with other regulatory documents from the manufacturer. Combustion Type and Fuel Type have
specific options for a manufacturer to choose.
GEM Engine Definition
Manufacturer Name
(e.g. Cummins)
EPA
Combustion Type Fuel Type Family Name Calibration ID
(Compression Ignition / Spark Ignition) (Diesel / Gasoline / LNG / CNG) (e.g. abed12345efg) (e.g. 123abc)
Compression Ignition Diesel GENERIC 1
Figure 29: Sample Engine Input File Header Information
The manufacturer then specifies the single engine idle speed point (in RPM) at curb idle
transmission torque (CITT), the engine full-load torque curve, and the engine motoring torque
curve. Torque curves are specified in RPM and Nm, and procedures for producing the torque
32
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curves, including the number of speed and torque points to measure, are specified in 40 CFR
1065.510. Finally the manufacturer provides the four-point engine idle fuel map and the 143-
point engine fuel map. The speed, torque, and fuel rate in the fuel maps are specified in RPM,
Nm, and g/s, respectively. Procedures for generating the idle and full engine fuel maps are
specified in 40 CFR 1036.535 and 1065.510. Figure 30 shows a summary of the sample engine
input file included with Phase 2 GEM.
Engine Idle Speed at CUT
RPM
750
Engine Full Load Torque Curve
Speed Torque
RPM Nm
0 0
750 440
907 580
1055 690
2601
0
Engine Motoring Torque Curve
Speed Torque
RPM Nm
0 -129
750 -129
907 -129
1055 -130
2700
-199
Engine Idle Fuel Map
Speed Torque
RPM Nm
600 17
700 17
600 88
700 88
Engine Fuel Map
Speed Torque
RPM Nm
750 0
750 44
750 88
Fuel Rate
grams / sec
0.21
0.23
0.46
0.50
Fuel Rate
grams / sec
0.2
0.35
0.53
2218 642 8.41
Figure 30: Sample Engine Input File Engine Characteristics
33
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The first row of the GEM input file for transmissions shows the GEM version, and
manufacturers would fill in the fifth row with the transmission's Manufacturer Name, Type, and
Model Name (see Figure 31). The vehicle manufacturer can choose any Manufacturer Name and
Model Name for the transmission, but it should remain consistent with other regulatory
documents. The transmission Type has specific options for the manufacturer to choose.
GEM Transmission Definition
Manufacturer Name Type Model Name
(e.g. Eaton) (AMI / MT / AT / DCT) (e.g. 7100)
EPA ' AT ' HMD
Figure 31: Sample Transmission Input File Header Information
Vehicle manufacturers would provide the gear ratios for their specific transmission, as
seen in the sample shown in Figure 32. If the transmission is an automatic transmission that has
a lockup gear other than the one programmed in the GEM shift strategy, the benefits of this will
not be recognized unless a powertrain test is conducted.
Transmission Gears
Gear Number Gear Ratio
1 47
2 221
3 1.53
4 1
5 0.76
Figure 32: Sample Transmission Input File Transmission Gear Ratio Information
Users may opt to use engine and transmission performance data obtained from a
powertrain test in their GEM runs. Procedures for generating the data to populate a powertrain
input file can be found in 40 CFR 1037.550. This section summarizes the input file format.
The first row of the GEM input file from powertrain testing show the GEM version and
manufacturers would fill in the fifth, ninth, and thirteenth rows with the relevant information
about the engine, transmission and powertrain, respectively. Figure 33 shows the header
information required by the model.
34
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GEM Powertrain Definition
Engine Manufacturer Name
(e.g. Cummins)
Cummins
Transmission Manufacturer Name
(e.g. Eaton)
Eaton
Powertrain Family Name
(e.g. abcd12345efg)
SrnartAdvantage
Combustion Type
(Compression Ignition / Spark Ignition)
Compression Ignition
Type
(AMI / MT / AT / DCT)
AMT
Calibration ID
(e.g. 123abc)
CAL1
Fuel Type
(Diesel / Gasoline / LNG / CNG)
Diesel
Gears
Number
Family Name Calibration ID
(e.g. abcd12345efg) (e.g. 123abc)
ISX CAL1
Model Name
(e.g. 7100)
10 ULTRASHIFT13LAS
Powertrain Test Configuration
(1: Trans. Output, 2: Wheel Hubs)
Figure 33: Sample Powertrain Input File Header Information
The next rows of the powertrain input file, as seen in Figure 34, include the engine idle
fuel rate and the powertrain performance information from the 55-MPH, 65-MPH, and Transient
drive cycle tests. Users would supply the cycle work, output speed/vehicle speed, and fuel mass
according to the procedures outlined in 40 CFR 1037.550(o).
Engine Idle Fuel Rate
grams / sec
0.576
55 MPH Cruise
Powertrain Cycle Work N/V
kWh rev / meter
25.28 0.86
25.25 0.93
Fuel Mass
grams
5031
5050
18.85
1.00
65 MPH Cruise
Powertrain Cycle Work N/V
kWh rev / meter
29.49 0.86
29.62 0.93
3845
Fuel Mass
grams
5780
5865
21.32
1.00
Transient
Powertrain Cycle Work N/V
kWh rev / meter
8.28 0.86
8.41 0.93
4371
Fuel Mass
grams
2012
2027
8.01 1.00 1930
Figure 34: Sample Powertrain Input File Performance Information
35
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GEM Output File Structure
An output file will be generated when the vehicle simulation completes and it is
automatically saved to the same location as the input file. As will be described in the following
section, the output file naming convention depends on the method chosen to run GEM. If users
run GEM from the Start Menu or command prompt, the output file name will be given the same
name as the input file with a "_result.csv" extension. If users choose to run GEM using the
Excel macro template, the output file will be renamed to match the date and time of the
simulation, in the format: GEM_YYYYMMDD_HHmmSS_result.csv. During the simulation
using either method, an error log file will be generated, even if there are no errors, with the same
base name as the output file, except that the "_result.csv" extension would be replaced with a
"_errors.txt" extension.
Each output file is identical to the input file for the vehicle modeled, except that the last
columns of the .csv file are populated with the model's results. Figure 35 shows the results of an
example simulation. The results fields are the same for each vehicle type, but their column
location in the file varies. The first result column indicates the date and time when the
simulation was performed. The next two columns are the raw GEM CO2 emissions and fuel
consumption values. The next two columns are the Family Emissions Limit (FEL) values EPA
and NHTSA will use for compliance. EPA's CO2 results are integer values. NHTSA's fuel
consumption results are calculated from those CO2 integer values, and are reported with four
decimal place precision to ensure consistency between the agencies' results.
Date/Time of Run GEM C02 Emissions GEM Consumption FEL C02 Emissions FEL Fuel Consumption Subfamily Subfamily FEL Subfamily Volume
YYYYJvlMDDJHHMMSS g C02/ton-mile gal/1000 ton-mile g C02/ton-mile gal/1000 ton-mile Name g C02/ton-mile #
2015-0602 08:50:58 79.41483702 7.80106454 79 7.7603
2015-060208:51:09 113.4204621 11.14149922 113 11.1002
2015-060208:51:22 83.93181444 8.24477549 84 8.2515
2015-060208:51:33 5047378154 495813178 50 49116
2015-060208:51:43 7392637368 7.26192276 74 7.2692
2015-060208:51:52 82.33588608 8.08800453 82 8.0550
2015-060208:51:58 103.9311183 10.20934365 104 10.2161
Figure 35: Example Results Columns in GEM Output File
The final three columns of the output file are left blank by the model. Manufacturers
would manually add the appropriate subfamily name, target FEL for the given subfamily, and the
volume of vehicles that will use the resulting FEL value prior to submitting their output file for
compliance.
Running GEM
There are three options for running GEM. The first option directly accesses the program's
executable file via the Start Menu folders, the Start Menu search, or a GEM icon on the
computer's desktop screen. This first option initiates the GEM graphical user interface (GUI) to
select and run the model. The second option uses the command prompt, which can also initiate
the GEM GUI, but has the option to suppress it. The third option uses a Microsoft Excel macro
to convert a spreadsheet template into the appropriate input files and run the executable with the
GEM GUI. Each of these options is described in the following sections.
36
-------
Prior to running GEM, it is important to locate all of the necessary input files. Many
computers will produce warnings if the users try to make changes to files in the installation
folder if it is located in the C:\Program Files directory. It is recommended that users save a copy
of the input file templates from the installation folder (i.e., C:\Program Files\US EPAVPhase 2
GEM\Sample Input Files - RELOCATE BEFORE USE) to a location on their hard drive (e.g.,
C:\Documents and Settings\UserName\My Documents). These files can then be changed as
needed to reflect the users' specific vehicles. See the previous sections for a description of the
input files.
Tractors that qualify for the heavy-haul regulatory subcategory designation have special
instructions for their vehicle input file. These tractors are not required to perform aerodynamic
testing to obtain an aerodynamic drag area, CdA, for their GEM input. As a result, users are
instructed to use a CdA value of "NA" for all heavy-haul tractors. This value is added to the
third column of the tractor vehicle input file. All other fields should be populated using the same
instructions provided previously for tractors.
Vocational vehicles that qualify for the emergency vehicle regulatory subcategory
designation also have special instructions for their vehicle input file. These manufacturers are
only allowed to apply lower rolling resistance tires to their steer and drive tires. They do not
have to provide engine or transmission information, and do not have the option of applying
technology inputs. If the Regulatory Subcategory field in the vehicle input file is populated with
an emergency vehicle (i.e., HHD_E, MHD_E, or LHD_E), users must fill-in the remaining fields
in the file with "NA" or "N" as appropriate. See the sample input file for vocational vehicles for
an example.
Output files from the GEM simulations are automatically saved in the same location as
the input files. They can be identified by their "_result.csv" or "_errors.txt" file extensions.
Identical output files are generated for each of the methods described below.
Users can access the Phase 2 GEM executable from the Start Menu. Go to Programs >
EPA Phase 2 GEM > Phase 2 GEM as shown in Figure 36.
37
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Phase 2 GEM Sample Input
" Phase 2 GEM User Guide
41 Phase 2 GEM
RleZilla FTP Client
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Figure 36: How to Access Phase 2 GEM from the Start Menu
Alternatively, users can access the executable by typing "Phase 2 GEM" in the Search
programs and files box located at the bottom of the Start Menu, and hitting "Enter". If users
select the option - "Create Desktop Icon" during installation, users can double click the icon
(shown previously in Figure 6) to run GEM as well to initiate the program.
Once the executable is selected, a window will ask the user to select an input file, as
shown in Figure 37. By default, the program will first look in the installation folder. As
mentioned previously, all of the input files are in a separate location to avoid permissions
warnings, and the necessary transmission and engine input files are located in the same directory
as the input file to be run. In this example, we are storing our files on the Desktop. Select the
appropriate input file (GEM_Sample_TRACTOR.csv in Figure 38) to begin the simulation.
38
-------
Select an Input File
(-)( / | > Computer > OSDtsk(C:) » Program Files > USEPA t Phase2GEM
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- Text Files (".csv'.MJ
Figure 37: Popup Window to Select an Input File Using the Start Menu Option; Defaults to Installation
Folder
Select an Input File \-S3-l
{C&\ J*\ * GEM Sample Input Files > Tractor "" *t [ Sect* < P
Organse » New folder
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1 B5 EPA_Sample_350hp.csv 5/29/2015 12:27 PM Microsoft Excel C.,. 3KB
Sg EPA_Sample_455hp.csv 5/29/2015 9:53 AM Microsoft Excel C.,. 3KB
g] EPA_Sample_AMT.csv 5/28/2015 3:32 PM Microsoft Excel C., 1KB
dj EPA_Sample_MT.csv 5/28/2015 332 PM Microsoft Excel C-,. 1KB
^Tj EPA^Sample_PT,csv 5/28/2015 3:32 PM Microsoft Excel C... 2 KB
9J GEM_TRACTOR.csv 5/29/2015 3:42 PM Microsoft Excel C... 2Kfi|
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GEM.TRACTOR.csv " [ Text Files ( ".csv '.M ) »|
Open Cancel
Figure 38: Location of Input Files for Example GEM Simulations
Once the input file is selected, the program will begin to run. A status window will step
through each configuration as it runs, as shown in Figure 39. At any point in the simulation,
users can stop the model by clicking the red "X" at the top right corner of the status window. A
new window will appear that asks "Cancel current simulation?" If the user chooses "Yes", it will
stop execution (once the current simulation has completed, which may take a few seconds) and
produce an output file with only the configurations that completed.
39
-------
EPA Phase 2 GEM v 1.0
US Environmental Protection Agency
Heavy Duty Phase 2 GEM v1.0
Processing Run DTRAC1 Complete!
Processing Run DTRAC2
Figure 39: Sample Status Window Showing Progress of GEM Simulations
The status window will indicate when the simulations are complete with a window
similar to Figure 40. The resulting output file will be saved in the same location as the input file,
and will be given the same name as the input file with a "_result.csv" extension added to the end
("GEM_Sample_TRACTOR_result.csv" in this example). When the simulation is complete,
users can close the status window by clicking the red "X" in the top right corner of the window.
| EPA Phase 2 GEM v 1.0
I ci. | S
Processing Kun IL. K^LI
Processing Run IDTRAC2
Processing Run IDTRAC3
Processing Run ID TRAC4
Processing Run IDTRAC_PT1
Processing Run IDTRAC_PT2
Processing Run IDTRAC_PT3
- Batch Simulation Complete! -
Complete! ^
Complete:
Complete:
Complete:
Complete!
Complete!
Complete!
COMPLETE!
Figure 40: Sample Status Window Showing Complete GEM Simulations
This first example simulation completed without any errors. No errors were produced in
the status window or the error log, shown in Figure 41, provides confirmation.
40
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J GEM_TRACTOR_errors.txt - Notepad
File Edit Format View hjelp
us EPA Phase 2 GEM vl.O Error Log-- NO Errors Found
Figure 41: Sample Error Log with No Errors from Simulation
If an error occurs in any simulations, the window will indicate the configurations that
failed and the model will continue to the next simulation. In the example of Figure 42, Run ID
"TRAC1" and "TRAC2" failed. The runs with errors are displayed in the status window and
indicated in the resulting output file, as seen in Figure 43 and Figure 44. Additionally, GEM will
produce a separate file, shown in Figure 45, with an extension of_errors.txt" that lists details
about any errors in a set of simulations.
EPAPhase2GEMvl.O
US Environmental Protection Agency
Heavy Duty Phase 2 GEM vl.O
Processing Run IDTRAC1 FAIL!
Processing Run IDTRAC2 FAIL!
Processing Run IDTRAC3
Figure 42: Sample Status Window Showing Progress of GEM Simulations with Failed Runs
EPA Phase 2 GEM v 1,0
Processing Kun !U' KALI I-AIU
Processing Run ID TRAC2 FAIL!
Processing Run ID TRAC3
Processing Run ID TRAC4
Processing Run IDTRAC_PT1
Processing Run IDTRAC_PT2
Processing Run IDTRAC_PT3
- Batch Simulation Complete With 2 Errors!
A
Complete!
Complete!
Complete!
Complete!
Complete!
-
=
-
COMPLETE WITH 2 ERRORS!
Figure 43: Sample Status Window Showing Complete and Failed Simulations
41
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GEM Vers P2_v1 0 AerodynanTire Steer Axle Drive Axle Drive Axle Engine Transmiss Technolog; Technology Technolog1 Technology Technology Technology
Run ID RegulatoryAerodynanLoaded TirCoefficient Coefficient Ratio Data Data Weight Re Vehicle Sr. Single Driv Part Time Low Frictic Predictive
Unique Ids (e.g. C8 Sm"2 m kg/t kg/t # File Name File Name Ibs MPHorN/Y/N Y/N Y/N Y/N
TRAC1 - ERROR, see error tie for details!
TRAC2 - ERROR: see error fit for details!
TRAC3 CB DC LF 5.3 0 47 6.8 6.9 3 82 EPA Sam EPA Sam 0 60 N N N N
TRAC4 C8 HH 5
TRAC PT'CB SC Ml 59
TRAC PT;C8 DC Ml 5.8
TRAC PT:C7 DC HF 6.1
0.5 6.5 69 3.7 EPA Sam EPA Sam 0 NA N Y N N
05 65 69 3 37 EPA Sam EPA Sam 0 NA N N N Y
0.5 6.2 6.3 3.7 EPA Sam EPA Sam 0 NA N N N N
0.5 4.8 5.1 2.95 EPA Sam EPA Sam 700
MA N IN jv IN
-
'
OEM TRACTOR wlrrors result I ffl
Figure 44: Example Output File with Two Errors
T I GEM_TRACTOR_wErrors_errors.txt- WordPad
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Zoom Zoom 100
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Status bar
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1*3 Measurement units •
Settings
US EPA Phase 2 GEM vl. 0 Error Log
TRACl — Invalid Loaded Tire Radius Value "14" outside of
allowable range ( 0.30 - 0.60 )
TRAC2 — Invalid Technology Improvement Single Drive Axle only
available for C8 vehicles
100% (-)
Figure 45: Example Error Log Resulting from Failed Configurations
Running GEM Using the Command Prompt
Users can also initiate GEM using the command prompt. As seen in Figure 46, the
command prompt can be found using the Start Menu's Search programs and files feature. Once
the executable cmd.exe is selected, a command window similar to the one shown in Figure 47
will display.
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Programs (1)
SB cmd
/ ' See more results
x .Shutdown i >
Figure 46: Initiating the Command Prompt from the Start Menu Search Bar
Figure 47: Windows Command Prompt Window
Users can use the command line to run GEM using the GUI by typing the location and
name of the GEM executable as shown in Figure 48. Note that Windows requires quotation
marks (" ") surrounding folder and file names that contain spaces. Users would then be
prompted to select the input file as seen previously in Figure 37 and be shown the progress of the
code as shown in Figure 39 and Figure 40.
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! C:\windows\sy stem32\cmd.exe
icrosoft windous [Uersion 6.1.7601]
Copyright 2009 Microsoft Corporation.
fill rights reserved.
:\Users\UserNane>"C:\Progran Files\US EPflXPhase 2 GEM\GEM.exe'
Figure 48: Command Prompt to Initiate GEM with the GUI Option
Alternatively, users have the option of bypassing use of the GUI by including the location
and name of the input file, and adding "-c" to the end of the command, as shown in Figure 49. In
this example, the executable is stored in the default Program Files location and the input files are
located in a folder on the desktop. Also seen in Figure 49, the output generally shown in the
GEM status window is displayed in the command window instead.
icrosoft II in do us [Ue
Dpyright 2009 Mi
n 6.1.7601]
oft Cornorat
FilesSUS EPnsPhase 2 GEMXGEM.
ilesSTractorSGEM_TRBCTOFI.csu"
ers \Userl,
auy Duty Phi
>US Environmen
se 2 GEM ul.0
rocessing Run ID TRAC1
rocessing Run ID TRAC2
rocessing Run ID TRAC3
rocessing Run ID TRBC4
rocessing Run ID IRBC_PI1
rocessing Run ID TRBC_PT2
rocessing Run ID IRBC_PI3
— Batch Simulation Complete* —
.Complete!
.Complete!
.Complete!
.Complete!
Complete!
Complete!
Complete!
Figure 49: Command Prompt to Initiate GEM and Directly Apply Input Files (no GUI Option)
Similar to the Start Menu method, the command window will display errors if they occur
in the simulation, as shown in Figure 50. Also, an identical error log file as was shown in Figure
45 is generated to show the specifics of the errors.
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! C:\windows\sy stem32\cmd.exe
icrosort windows [Uersion 6.1.7601]
Copyright 2009 Microsoft Corporation. fill rights reserved.
::SUsersSUserNane>"C:SProgran FilesNUS EPBSPhase 2 GEM\GEM.exe" "C:SUsersSUserNa
eSDesktopSGEM Sample Input FilesVTractor\GEM_TRflCTOR_wErrors.csu" -c
Heauy Duty Phi
ID TRBC1 ...
ID TRBC2 ...
ID TRBC3 ...
ID TRBC4 ...
ID TRBC_PT1
ID TRBC_PT2
ID TRBC_PT3
.Complete!
.Complete!
Cor n '
Coi
....Complete
Complete With 2 El
Figure 50: Command Prompt Display When an Input File Contains Errors
Users can also proactively check if their output file contains errors by including "-t" in
their command to initiate GEM, as shown in Figure 51. This option will not run this simulation.
Instead, it simply warns the user which runs contain errors. The validation information is
repeated in the "_results.csv" file that is generated, as shown in Figure 52. An error log (with
extension "_errors.txt") is also created to provide more specific information about the errors.
icrosoft II in do us [Ue
opyright 2009 Mi
n 6.1.7601]
oft Corporat
FilesSUS EPHSPhasi
ilesSTractorSGEMJTi
2 GEMSGEM.
sctor_uErro
Heavy Duty Phase 2 GEM u
recessing Run ID TRAC1
recessing Run ID TRAC2
recessing Run ID TRAC3
recessing Hun ID IRBC4
recessing Hun ID TRBC_PT1
recessing Run ID IRBC_PI2
recessing Run ID IRBC_PI3
.FfllL!
.FfllL!
Input Ualid!
Input Ualid!
Input Ualid!
Input Ualid!
Input Ualid!
— Batch Simulation Complete With 2 Errors! —
Figure 51: Command Prompt to Check Errors Prior to Running GEM
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m a
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GEM_Tractor_wErrors_result.c5v- Excel
DATA REVIEW VIEW DEVELOPER
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& Insert - Z - Ay
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5
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j atory Category v
B CO E W
^equlatory Cateqorv (Tractor
Manufacturer Name
Model Year
GEM Version
P2 v1 0 Aerodynamic
Run ID Regulatory Subcategory Aerodynamic Drag Area (CdA)
Unique Identifier (e.g. C8_SC_HR) m"2
TRAC1 - ERROR: see error file for details!
TRAC2 - ERROR: see error file for details!
TRAC3 - Input Validated
TRAC4 - Input Validated
TRAC PT1 - Input Validated
TRAC PT2 - Input Validated
TRAC PT3 - Input Validated
GEM_Trartor_wErrors_resutt
Tire
Loaded Tire Radius
m
Steer Axle Tire
Coefficient of Rolling Resistance Level
ko/t
|
Dni
Col
1
»
Figure 52: Resulting Output File from GEM Input Validation
Running GEM from Microsoft Excel
GEM can also be initiated using the Microsoft Excel templates and their embedded
macros. This option requires more user-interaction, but does have some helpful features to catch
errors before running the model. The template files that include the GEM macro are saved for
each vehicle category as "Microsoft Excel Macro-Enabled Worksheets", with a file extension of
".xlsm".
When the Excel template is first opened, users may get a warning at the top of the file,
similar to the warning shown in yellow in Figure 53. Users should select the "Enable Content"
button to ensure that GEM will run properly from this macro.
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UXIK TUU
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• I u • -.. Bu-i
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> is ir **
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Figure 53: Warning in Macro-Based GEM Files; Click the "Enable Content" Button to Run the Model
Figure 54 shows the layout of the macro-enabled example input file for tractors. This
input file layout in the first tab (labeled "GEM Data") is identical to the layout of the tractor
input file discussed in previous sections, except that this file includes "Validate" and "RUN
GEM" buttons in cells A4 and B4. This file also includes two additional tabs that provide
additional input for the user. The "Naming Structure" tab provides the naming convention for
the regulatory subcategories. These names are the same as those seen in Table 17, Table 20, and
Table 23 for the tractor, vocational and trailer categories, respectively. The "Input Limits" tab
describes the input value ranges associated with each of the input fields.
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Si H *3 ' GEM.JRACTOR.xsm- Excel
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Validate
Run ID
Unique Identifier
TRAC1
TOAC2
TRAC3
TRAC4
TRAC PT1
TRAC PT2
TRAC PT3
GEM Data
B
Tractor
RUN GEM
Regulatory Subcategory
(e.g. C8 SC HR)
C8 SC HR
C7 DC HR
C8 DC LR
C8 HH
C8 SC MR
C8 DC MR
C7 DC HR
C
D E T|
Aerodynamic
Tire Steer Axle Tire
Drive/
Aerodynamic Drag Area (CdA) Loaded Tire Radius Coefficient of Rolling Resistance Level Coefficient of Rolli
m*2 m kg/t k
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NA
59
58
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Naming structure I
put Limits
0.50 6.5 (
050 6.9
047 6.8
1
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0 50 6.5 6
050 65 (
050 6.2 i
0.50 4.8 S
1-
i l«l I'l
Figure 54: Sample Microsoft Excel Macro Input File
Users have two options to check for errors prior to running the model. The Excel macro
is designed to catch some errors by displaying the erroneous fields with text that is red and
crossed-out. If the user enters an input value that is out of range, uses lowercase letter, or repeats
a unique identifier, the value will be replaced with red text with a line through it (see Figure 55).
I
ft
Cli
T
1
2
3
4
5
6
/
8
9
10
11
12
13
14
16
16
17
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4
A
Regulatory Category
Manufacturer Name
Model Year
Validate
Hun ID
Unique Identifier
TRAC1
TRAC2
TT1AC3
TOAC4
TRAC PT1
TRAC PT2
TRAC PT2
GEM_TRACTORj;lsm - Excel ? S - d X
*T PAGE LAYOUT FORMULAS DATA REVIEW VIEW DEVELOPER
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V Jill
• B
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| RUN GEM
Regulatory Subcategory
(e.g. CS SC HR)
C8 SC HR
C7 DC HR
C8 DC LR
C8 HH
C8 SC MR
C8 DC MR
C7 DC HR
-5 <=- • ^Conditional Formatting- U= Insert - 51- Aw AA
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Aerodynamic Drag Area (CdA) Loaded Tire
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Radius Coefficient of Rolling Resistance Level Coefficient of Rolli
kgft k
62 14J» 6.5 9
64 050 6.9 i
1^^^ 5.3 0.47 6.8 EJ
m 050 6.5 6
5.9 050 M 6
1 58 050 6.2 (
61 0 50 48 B
> GEM Data Naming : ...
s
H
Figure 55: Sample Microsoft Excel Input File with Errors
Users can also click on the "Validate" button in cell A4 to check for errors. Once the
validation process is complete, the "_result.csv" and "_errors.txt" files will automatically be
displayed. If a user does not fix errors identified in either of these methods, the model will still
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run, but will produce errors in the output file and no certification results will be available for
those runs. The macro will not provide a warning for mistyped supplemental file names (i.e.,
engine, transmission, or powertrain files) or incorrect file paths. Instead, it will produce a failed
run for that simulation and the error message will note that it could not locate the file. Also, the
model will not produce an error if a unique identifier is repeated, as seen in Figure 55 for the
unique identifier "TRAC_PT2".
Once the inputs are properly specified in Excel, the user clicks the "RUN GEM" button
to initiate the program. Please be patient. It may take a few seconds to begin. Users cannot
make changes to the input file and may have limited access to Excel until the simulations are
complete. Users can stop the simulation at any point by clicking the red "X" in the upper right
corner of the status window. Users will be presented with a window to confirm that they want to
end the simulation. The results and error logs will still be generated for the simulations that
completed before the user chose to stop the model.
EPA Phase 2 GEM v 1.0
US Environmental Protection Agency
Heavy Duty Phase 2 GEM v1.0
Processing Configuration 1 Complete!
Processing Configuration 1_1 Complete'
Processing Configuration 1_2 Complete!
Processing Configuration 2...
Figure 56: Status Window to Show Progress of GEM Simulations
Once complete, the result and error files will automatically be opened. When using the
GEM Excel Macro, the output files will be renamed to match the date and time of the simulation,
in the format: GEM_YYYYMMDD_HHmmSS_result.csv. The error file is saved with the
same timestamp and a "_errors.txt" extension.
Final Notes
For more information on the rule, please see Docket EPA-HQ-OAR-2014-0827 available
at http://www.regulations.gov.
^'Peer Review of the Greenhouse gas Emissions Model (GEM) and EPA's Response to Comments," Docket # EPA-
420-R-15-009, June 2015.
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