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and Air Quality October 2005
COMMUTER Model v2.0
User Manual
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EPA420-B-05-017
October 2005
COMMUTER Model v2.0
User Manual
Transportation and Regional Programs Division
Office of Transportation and Air Quality
U.S. Environmental Protection Agency
Prepared for EPA by
Thomas R. Carlson, Sierra Research, Inc.
Robert G. Dulla, Sierra Research, Inc.
J. Richard Kuzmyak
Updated by
Christopher D. Porter
Cambridge Systematics, Inc.
EPA Contract No. GS-10F-0198N
NOTICE
This technical report does not necessarily represent final EPA decisions or positions.
It is intended to present technical analysis of issues using data thatC are currently available.
The purpose in the release of such reports is to facilitate the exchange of
technical information and to inform the public of technical developments which
may form the basis for a final EPA decision, position, or regulatory action.
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Table of Contents
page
1. INTRODUCTION 1
1.1 What is the COMMUTER model? 1
1.2 Who will use COMMUTER? 1
1.3 Why was COMMUTER created? 1
1.4 What Programs can I evaluate with COMMUTER? 2
1.5 What methodology does COMMUTER use? 2
1.6 When can I use COMMUTER, and when should I not use it? 3
1.7 What do I need to do to get started? 4
1.8 What other documentation is available? 5
1.9 What has Changed Compared to COMMUTER Version 1.0? 5
2. USING THE MODEL 7
2.1 What type of computer equipment and software do I need? 7
2.2 How do I install and operate COMMUTER? 7
2.3 How do I begin once the program is installed? 10
2.4 How do I input data? 11
2.5 Is there help available when inputting data? 14
2.6 Can I save my inputs to use in another analysis? 16
2.7 Can I use my own emission factors? 16
2.8 How do I view the results? 18
2.9 How do I print my data and results? 19
2.10 Can I tell the model to remember where my files are stored? 21
2.11 What do I do when I'm finished? 22
3. GENERAL INPUT SCREENS 23
3.1 Scenario Information 23
3.2 Local Data 28
3.3 Edit Coefficients 32
4. TCM-SPECIFIC DATA 35
4.1 Site Access and Transit Service Improvement Programs 35
4.2 Financial Incentive and Parking Cost Programs 39
4.3 Site-Specific Employer Support Programs 41
4.4 Area-Wide Employer Support Programs 45
4.5 Alternative Work Schedule Programs 46
5. EMISSIONS-RELATED INPUT SCREENS 50
5.1 Fleet Emissions Information 50
5.2 Other Emissions-Related Data 55
6. REFERENCES 59
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List of Tables
page
Table 1 Summary of COMMUTER Data Inputs 12
Table 2 Default Speeds (mph) by Area Size 58
List of Figures
page
Figure 1 COMMUTER Startup Screen 9
Figure 2 Menu Structure 11
Figure 3 Model Layout Screen 15
Figure 4 Sample Output Report 20
Figure 5 Scenario Information Input Screen 24
Figure 6 Local Data Input Screen 30
Figure 7 Edit Coefficients Input Screen 34
Figure 8 Site Access and Transit Improvements Input Screen 36
Figure 9 Financial Incentives Input Screen 39
Figure 10 Site-Specific Employer Support Programs Input Screen 42
Figure 11 Area-Wide Employer Support Programs Input Screen 46
Figure 12 Alternative Work Schedules Input Screen 48
Figure 13 Fleet Emissions Information Input Screen 51
Figure 14 Other Emissions-Related Data Input Screen 56
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1. INTRODUCTION
1.1 What is the COMMUTER model?
The COMMUTER model (subsequently referred to as simply "COMMUTER") is a
spreadsheet-based computer model that estimates the travel and emissions impacts of
transportation air quality programs focused on commuting. The model is particularly
useful for programs such as those recognized under the EPA's Best Workplaces for
Commuters and other Commuter Choice Programs.
1.2 Who will use COMMUTER?
EPA designed COMMUTER for two types of users:
Metropolitan Planning Organizations (MPOs) and state Departments of
Transportation (DOTs) who are assessing emissions impacts of various
Transportation Control Measure Strategies. These impacts can be incorporated
into State Implementation Plan (SIP) analyses.
Individual employers who are assessing the likely effectiveness of various
commuter benefit packages and other measures to facilitate use of commute
alternatives.
MPOs and DOTs can also provide guidance and assistance to employers participating in
voluntary programs on the application of this tool.
1.3 Why was COMMUTER created?
COMMUTER was designed to help simplify the effort required by air quality planners to
estimate travel and emission effects resulting from Transportation Control Measures. The
model can also be used to estimate the benefits of site-specific Commuter Choice
(employer-based transportation) programs to assist employers in designing a program
appropriate for them.
The 1990 Clean Air Act Amendments mandated that the EPA and DOT provide guidance
on "the formulation and emission reduction potential of transportation control measures
related to criteria pollutants and their precursors" (Section 108(f)). In the early 1990s,
EPA developed a number of tools and guidance documents to assist communities in
developing these measures and taking credit for the resulting emission reductions.
Because the effects of TCMs on travel activity and emissions can be very complex, the
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guidance included many aspects of vehicle operation and other factors that affect
emissions. The guidance documents were often very detailed and difficult to use.
COMMUTER consolidates existing TCM guidance, and is based on "state-of- practice"
methodologies and data. COMMUTER will reduce the time required to calculate the
benefits of regional and employer-based TCMs. It will also save regional government
resources, since these governments will have less need to develop their own models and
tools.
1.4 What Programs can I evaluate with COMMUTER?
You can use COMMUTER to evaluate these types of programs, either for a defined
region within an urban area, or for individual employers:
Transit fare decreases or other incentives that reduce the cost of using transit;
Transit service improvements (faster or more frequent service);
Ridesharing programs, in which employers support carpooling and/or vanpooling
through on-site programs, financial incentives, or preferential parking;
Other actions, such as increased parking charges or cash-out programs, that
change the time and/or cost of traveling by any particular mode;
Non-motorized (e.g., bicycle and pedestrian) commuting programs;
Alternative work schedules, including flex-time, compressed work weeks, and
staggered work hours; and
Telecommuting.
1.5 What methodology does COMMUTER use?
COMMUTER is broken down into two components: travel impacts and emissions
impacts.
The travel impacts component uses a logit mode-choice model referred to as the "pivot
point" approach. This approach allows you to analyze the effects of several strategies
simultaneously. Mode choice models have been developed for many cities and regions
nationwide, so you can often use coefficients that have already been developed to reflect
local characteristics. This component will calculate the impact of the mode share changes
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from these programs and translate the mode share changes into changes in trips and
vehicle miles traveled (VMT). In addition, COMMUTER contains an input option that
allows you to enter mode share changes directly (such as might be obtained from
employee survey data) as an alternative to the pivot point-based calculation performed
internally by the model.
The emissions component is based on EPA's MOBILE6.2 model. MOBILE6.2 emission
factors were generated and loaded into COMMUTER for several sets of local conditions.
You can select the conditions most appropriate for your area, and the model will apply
the corresponding emission factors in calculating and outputting emission reduction
impacts. If you are an experienced MOBILE6.2 user, you can also generate your own set
of MOBILE6.2 emission factors (reflecting your exact local conditions) that can be
imported into COMMUTER. In fact, if you intend to use COMMUTER to produce
emissions reduction estimates for SIP submittals or conformity determinations, your
emission outputs from COMMUTER must be based on an imported MOBILE6.2* run
using your own local or state information. See the BWC SIP and Conformity Guidance
for more information on how to include control measures from BWC programs in SIPs
and conformity determinations.
1.6 When can I use COMMUTER, and when should I not use it?
COMMUTER is particularly useful for smaller Transportation Control Measures and can
be used for the purpose of calculating State Implementation Plan (SIP) credit or for
conformity determinations. The model will not perform as well for larger programs,
particularly those large enough to impact travel speeds throughout an area. If your
program is likely to have a regionally significant effect on travel patterns** it must be
analyzed within the modeling performed by the MPO during its regional emissions
analysis You should consult with your regional EPA office if you believe your program
can have these impacts. In this case, you can still use COMMUTER to calculate an
initial estimate of a potential program. You may want to do this to help you select a
program and determine if you want to further consider particular options.
EMFAC is required for SIP modeling in California. COMMUTER does not have the ability to import
EMFAC emission factor output.
**
40 CFR 93.101 defines a "regionally significant" project as "a transportation project (other than an
exempt project) that is on a facility which serves regional transportation needs (such as access to and from
the area outside of the region, major activity centers in the region, major planned developments such as new
retail malls, sports complexes, etc., or transportation terminals as well as most terminals themselves) and
would normally be included in the modeling of a metropolitan area's transportation
network, including at a minimum all principal arterial highways and all fixed guideway transit facilities that
offer an alternative to regional highway travel."
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IMPORTANT: COMMUTER is not designed to quantify baseline
travel or emissions. Instead, its purpose is to estimate travel and
emission changes associated with specific measures, based on
inputs you provide. Thus, although COMMUTER may be used to
calculated SIP credits for these measures, the baseline travel or
emissions estimates it generates will not exactly match your
baseline SIP inventory.
The COMMUTER Model is most appropriately applied to a single worksite, employment
center, or subarea for sketch-level analysis purposes. Its most robust predictive power
lies with measures that can be translated into time and cost strategies. The factors used
for employer support and alternative work arrangements are based on the best research
and professional judgment available. In most cases, though, the empirical evidence to
support these factors is very limited. Furthermore, the impacts of any one type of
program can vary substantially, depending upon the characteristics of the worksites being
evaluated, the employees who work there, and how effectively a given program is
implemented. For some planning purposes, therefore, it may be necessary to gather
additional empirical data and/or conduct more detailed modeling, in order to increase the
reliability of the estimate of a program's impacts.
1.7 What do I need to do to get started?
In order to run the model, you will need to gather background information about the
travel characteristics in your area. MPOs or Councils of Government (COGs) generally
compile this information for an area. Regional COGs are local government organizations
designed to study and recommend solutions to problems facing an individual region and
to help their local government members apply effective, coordinated regional planning.
MPOs are similar organizations that focus on transportation-related planning.
If you are an employer or other non-MPO user of this model, you should contact the MPO
or COG in your area. The National Association of Regional Councils (NARC) maintains
an Internet website at http://www.narc.org. From the NARC home page, you can access
information about the Association of Metropolitan Planning Organizations (AMPO) and
lists of COG and MPO links by state (http://www.narc.org/links/member.htmn. If you are
unsure of the appropriate source, you should consult with your regional EPA office to find
the appropriate source of information.
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You will also need specific background information for your particular program. This
user manual will assist you in determining the appropriate inputs into the model. Again,
if you have any further questions, you can consult with your regional EPA office.
1.8 What other documentation is available?
This user manual presents the key instructions needed for you to effectively develop
inputs and run COMMUTER. Although it attempts to provide you with enough
information to understand how to develop inputs and operate the model, it is not
exhaustive in detail. If you are interested in further understanding the theory behind the
modeling calculations, please consult the companion document to this user manual,
"Procedures Manual for the COMMUTER Modelv2.0"1*
1.9 What has Changed Compared to COMMUTER Version 1.0?
COMMUTER Model version 1.0 was originally released in 2000. Version 2.0, released
in 2005, incorporates a number of updates and changes to calculation procedures, to make
use of the most recently available travel and emissions data and to expand the model's
capabilities. Significant changes include the following:
The default travel parameters (e.g., mode shares, trip lengths) have been updated
using data from the 2000 U.S. Census, the 2001 Nationwide Household
Transportation Survey, and other recent sources.
The default and area-specific mode choice coefficients have been updated based
on a review of current national practice. Default coefficients are no longer
provided for different area sizes, since a review of the coefficients did not find
significant differences among urban areas of different sizes.
Some of the TCM impact values embedded in the model have been updated,
based on recent research. These include the mode share impacts for "level 3" and
"level 4" carpooling and vanpooling support, and default participation level for
telecommuting programs.
Emissions are now calculated using MOBILE6.2, EPA's most current version of
the MOBILE emission factor model, rather than MOBILESb.
Emissions are reported for seven additional pollutants, including particulate
matter (PM2.5, users can get PM10 output by importing their own MOBILE6.2
runs with PM10 output) and six air toxics, as well as for the four pollutants
originally reported by COMMUTER - volatile organic compounds (VOC), carbon
monoxide (CO), oxides of nitrogen (NOx), and carbon dioxide (CO2). Emissions
for some pollutants are now reported in pounds per day as well as in tons per day.
Superscripts denote references provided in Section 6.
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The procedure for calculating emissions changes has been revised for consistency
with MOBILE6.2 format emissions data. Additional user inputs may be
specified, including the percentage of vehicle-miles of travel (VMT) by facility
type, and average travel speeds for both freeways and arterials in both the peak
and off-peak periods. On the other hand, user inputs for the percentage of cold
starts are no longer required.
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2. USING THE MODEL
This section explains how to install COMMUTER and provides a general overview of
how to run each element of the program, as well as how to view and save your results.
Further details on the type of data required are provided in Section 3 (for general existing
condition inputs), Section 4 (TCM-specific information), and Section 5 (emissions-
related information).
2.1 What type of computer equipment and software do I need?
COMMUTER runs on personal computers using Microsoft's Windows 95 or later
operating systems. You must also have Microsoft Excel 95 (i.e., Excel 7.0) or a more
recent version of Excel installed. If your computer allows you to run these programs, you
can use COMMUTER. (However, if you have a Pentium-class CPU with less than 150
MHz, moving through the input screens may be slow at times.)
COMMUTER will work at 640 x 480, 800 x 600, and 1,024 x 768 display resolutions at
both 250-color and 16-bit (Hi-Color) depths, and should run at any available video
display setting.
The COMMUTER model itself requires a minimum of 2.0 MB of disk space. In
addition, the default MOBILE6 emission factors that may be used with the model are
provided in 192 external tab-delimited data files (.tbz) that require 12.2 MB when zipped
or 47.4 MB when unzipped. If disk space is a concern, the user may choose to retain only
the files that are relevant to their analysis area. If the user chooses to provide their own
MOBILE6 outputs, the output file will require approximately 40 MB of disk space.
2.2 How do I install and operate COMMUTER?
Installing the Program
Installing COMMUTER is quite simple. The model, along with some sample files, is
contained in the COMM1.EXE self-extracting archive file (which can be downloaded
from EPA's web site at http://www.epa.gov/otaq/transp.htm). Step-by-step installation
instructions are given as follows.
Step 1 - Create a new folder or directory on your computer where you want to install
and operate COMMUTER (e.g., C:\COMMUTER). (When you run COMMUTER, it
can create and re-use "scenario" files that store your data and assumptions for a
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particular analysis case or scenario. Thus, it is highly recommended that you create a
separate folder for COMMUTER so these files don't get mixed up with others.)
Step 2 - Download or copy the COMMUTER_v20.ZIP file to your computer and
unzip it, directing it to deploy all files to the folder or directory you just created.
When this is complete you should have a folder entitled "COMMUTER_v20" within
the directory you've chosen with the following items: the model itself,
COMMUTER_v20.xls; an example scenario file entitled Example Scenario_v20.vme;
a sample MOBILE6.2 input file entitled M6sample.in; and a folder entitled Data
containing 192 files with a .tbz extension. These files contain data related to the
Petroleum Administration for Defense Districts (PADDs) that are needed to compute
changes in emissions of air toxics. It is important that the Data folder be in the same
folder as COMMUTER_v20.xls. If the Data folder is in a different location,
COMMUTER will be unable to access the files.
Finally, you should check your macro security level in Excel to ensure that it is set on
"Medium." This is done by opening the "Tools" menu, selecting "Macro," and then
selecting "Security." You will have a choice of High, Medium, or Low security. Select
Medium. COMMUTER'S macros will not run if the security level set to High, and Low
is not recommended.
Running the Program
Once you have installed the program, there are several different ways that you can run the
program.
Create and launch a shortcut to the application;
Double-click* the COMMUTER_v20.xls file from within the Windows Explorer
or Internet Explorer window (assuming Excel has been installed and associated
with .XLS file types);
Right-click the COMMUTER_v20.xls file and click "Open" from the pop-up
menu; or
Click the Start button at the bottom left of the Windows desktop, select
"Documents" from the pop-up menu, and then click the COMMUTER_v20.xls
file from the pop-up list of documents. (This method will work only if you have
If the Windows Explorer has been replaced by Internet Explorer (e.g., in Windows 98), Internet Explorer
can be configured to launch programs with a single mouse click instead of a double-click.
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recently opened the COMMUTER_v20.xls file and it still appears in your
"Recent Documents" list.)
You cannot run the program by launching a previously created scenario file (.vme) from
the Windows desktop. Scenarios must be opened from within the program after it has
been launched in one of the ways described above. As the program launches you will see
a dialogue box stating that the file has macros and asking you to choose when to disable
the macros or enable them. Select "Enable Macros." As the program loads, you will see
a startup screen like the one shown below in Figure 1.
Figure 1
COMMUTER Startup Screen
COMMUTER MODEL
COMMUTER CHOICE & VOLUNTARY MOBILE SOURCE PROGRAM
TRAVEL AND EMISSIONS ANALYSIS TOOL
A
Release
1.0
INPUT LEGEND
-REQUIRED INPUT
- OPTIONAL INPUT
- LOCKED CELLS
- PROGRAM-CONTROLLED CELLS
- HELP TEXT
The startup screen includes an "input legend" showing the colors that are used to identify
the different types of cell ranges that you will see on the data entry screens. Different
colors are used to identify cells that you type inputs into and to highlight on-screen help
boxes as listed below:
light green - required input cells;
yellow - optional input cells;
white - locked (i.e., non-editable) cells;
gray - program-controlled cells; and
red - help text boxes.
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Required inputs must be typed into all light-green cells shown in the edit screens. You
can also supply inputs in the yellow shaded cells, but the program will run if they are left
blank. (However, it is a good idea to use these optional input cells to supply more
information about the analysis scenario you are constructing.) White and gray cells are
locked from editing and are used to display information. Finally, red cells highlight help
boxes containing brief instructions for the inputs being entered on each screen.
NOTE: When the program has finished loading, you will see a
"Ready" indicator at the bottom left of the application window.
The user interface for COMMUTER has been programmed to display on your entire
screen (i.e., in "full" screen). If you need to temporarily minimize the COMMUTER
application to the Windows taskbar (located at the bottom of the Windows desktop by
default), type "Ctrl-m" (i.e., hold down the Ctrl key and type "m"). To restore the
COMMUTER application to the full screen, just click its button in the Windows taskbar.
2.3 How do I begin once the program is installed?
Once the program finishes loading, you can select from four main menus listed at the top
of the screen: the File menu, the Edit Inputs menu, the Results menu, and the Help menu.
These menus will be available at the start of every session, and will allow you to enter
data (Edit Inputs menu), view results (Results menu), print results (File menu), get help
(Help menu), and retrieve or save data and results for a specific analysis (referred to as a
"scenario", accessed through the File Menu).
Figure 2 shows the structure of the main menu, which includes the "File," "Edit Inputs,"
"Results," and "Help" menus, and each of the sub-menu elements.
You will generally begin an analysis by clicking through the data entry elements in the
Edit Inputs menu in the order in which they are listed in the menu. (Once you have
defined an analysis, you can later load and edit a scenario from the File menu; this will be
discussed later in Section 2.6.) Each of the elements in the Edit Inputs menu corresponds
to the input screens for entering specific data required by COMMUTER. (Detailed
information on the data required for these screens is provided in Sections 3-5.)
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File Menu
Figure 2
Menu Structure
File Edit Inputs Results Help
Open Scenario
Save Scenario
Clear Scenario
Import Emission Factors
Empty Emission Factors
Print Inputs
Print Travel Results
Print Travel and Emission Results
Set Working Directory
Exit Program
Edit Inputs Menu
Edit Inputs Results Help
Scenario Information
Local Data
Edit Coefficients
Site Access and Transit Service Improvements
Einancial Incentives and Parking Costs
Employer Programs - Site-Specific
Employer Programs - Area-Wide
Alternative Work Schedules
Fleet Emissions Information
Other Emissions-Related Data
Results Menu
Results Help
View Travel Results
View Travel and Emission Results
Help Menu
Help
View Startup Screen
View Model Layout Screen
When the program is first loaded, some of the sub-menu elements shown in the Edit
Inputs menu will be shown as gray shaded-out text, which indicates that you have not yet
selected any TCM programs for analysis. (As explained below, you will make these
selections by using the check boxes at the bottom of the Scenario Information screen.)
2.4 How do I input data?
The Edit Inputs menu lists each of the input screens available. Some of the screens are
for inputting baseline (i.e., existing condition) information needed regardless of the type
of TCM being analyzed; others will be used only when analyzing a particular measure.
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IMPORTANT: The program will automatically size the width of
the data entry screens to the width of your monitor. However, the
length of some of the screens will exceed the monitor's vertical
display dimension. Therefore, for some input screens (such as the
Scenario Information and Local Data screens), you must scroll to
the bottom of the screen to complete the data entry required in that
screen by using the vertical scroll bar or the "Down Arrow " or
"Page Down " keys.
The information that must be entered in each input screen is listed in Table 1. The data
required in the first three screens ("Scenario Information," "Local Data," and "Edit
Coefficients") consist of general information, background travel data, and mode-choice
coefficients.
Table 1
Summary of COMMUTER Data Inputs
Input Screen
Scenario Information
Local Data
Edit Coefficients
Site Access & Transit
Service Improvements
Financial Incentives &
Parking Costs
Site-Specific Employer
Support Programs
Area- Wide Employer
Support Programs
Data Required
General information, including area size and scope (i.e., regional vs. site-
specific) being analyzed and the TCM programs being evaluated
Background travel data such as existing mode shares, trip lengths,
occupancy levels, baseline vehicle miles traveled, baseline speeds, and
option to provide final mode shares (after TCMs)
Provides default mode choice coefficients as a function of the area size
entered earlier and for selected cities, which can be edited by the user
Data required for analysis of either site access or transit service
improvement TCMs, including changes in site access walk times and
employer participation rates, and transit headway and route travel time
changes
Inputs for analysis of financial and parking incentive programs consisting
of changes in parking, transit fare, or other costs by travel mode
Parameters that specify either the program participation level or expected
mode share increase resulting from the implementation of an employer
(i.e., site) specific commuter choice program
Employer participation level inputs required for area-wide analysis of
commuter choice programs being implemented across a metropolitan area
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Table 1
Summary of COMMUTER Data Inputs
Alternative Work
Schedules
Fleet Emissions
Information
Other Emissions-Related
Data
Existing and expected eligibility or participation rates for alternative work
schedule programs being evaluated, such as flex time, compressed work
weeks, staggered hours, and telecommuting
Inputs required by the program in order to either apply a pre-generated set
of MOBILE6.2 fleet emission factors or to utilize locally generated
MOBILE6.2 emission factors imported into the model
Fleet travel mix (e.g., fraction of travel by vehicle class) and start fraction
inputs required by the program to calculate TCM emission reductions that
are specific to the local conditions being modeled
If you have not yet done any analyses or want to analyze a new scenario, you will start
with the Scenario Information screen to enter general background information and to
select the type(s) of TCM programs being evaluated. This selection is made by checking
the appropriate boxes shown at the bottom of the Scenario Information screen. You can
enter any non-blank character in the check boxes to activate analysis of the specific
TCMs.
Travel data should be entered using the Local Data screen, and you can use the Edit
Coefficients screen to edit the default mode choice coefficients provided with the
program. (Images of these screens and details on the data required are provided in
Section 3.) By default, COMMUTER calculates changes in mode share due to the types
and extent of specific TCM programs being modeled. If, however, you have estimates of
changes in mode share due to modeled programs, you can optionally enter the final mode
shares (resulting from changes to existing shares) in the Local Data screen.
Data for the specific TCM program(s) being evaluated are entered in the next five
screens. You will have access to only those screens that were selected (checked off) for
analysis in the Scenario Information screen. Detailed information on these screens is
provided in Section 4.
NOTE: If you have chosen to enter your own final mode share
estimates in the Local Data screen, you do not need to enter
information in any of the TCM-specific program screens. In this
case, the inputs in these screens are bypassed and the final mode
shares you have entered are used to compute VMT and trip impacts.
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Finally, you will enter emission-related data in the last two data screens (addressed in
Section 5). This will include either vehicle fleet parameters that allow the program to
find and apply a specific set of previously generated MOBILE6.2 emission factors that
approximate local conditions being modeled, or selection of MOBILE6.2 emission
factors that you have generated to more precisely reflect local conditions.
NOTE: You may see a "Calculate " annunciator on the status bar
at the bottom of the application window while you are entering
data. This is normal. During data entry, the program recalculates
only specific portions of the underlying spreadsheets in order to
speed up performance. Later, when you view or print results or
save the scenario data, all underlying sheets are recalculated.
If you are only interested in computing travel impacts, you do not need to enter any
emissions-related inputs in these last two screens.
2.5 Is there help available when inputting data?
From the Help menu, you can view a "Model Layout" screen that provides an overview
of the layout and data flow of COMMUTER. The Model Layout screen also identifies
the input screens that apply to specific voluntary measures and commuter choice
programs. Figure 3 shows the Model Layout screen. Note that on smaller monitors, you
may need to scroll down to view the entire screen.
You can also return to the Startup screen from the Help menu. (This is handy if you need
to refer to the cell coloring conventions used to guide you in entering model inputs.)
In addition, many of the input screens offer additional guidance on the specific data that
must be entered. In some screens, explanatory notes are shown next to the input cell. In
other screens, "help boxes" displayed with light red backgrounds provide more extensive
descriptions of key data inputs.
Once you've finished inputting all the required data for each screen (remember that in
some cases you may need to scroll down your screen to complete data entry), that screen
will appear with a checkmark («/") beside it the next time the Edit Inputs menu is
accessed. You can use the presence or absence of checkmarks as an easy visual reference
of additional data that must still be entered.
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Figure 3
Model Layout Screen
COMMUTER MODEL DATA LAYOUT
(SCROLL DOWN TO VIEW ENTIRE LAYOUT SCREEN!
GENERAL INPUT SCREENS
SCENARIO INFORMATION
General Information
Analysis Area Definition
Analysis Area Employment
TCM Programs Being Analyzed
LOCAL DATA
Existing Mode Shares
Existing Trip Length
Existing Occupancy
Peak Period Info
Observed Mode Shifts
from TCMs (optional)
MODE CHOICE MODEL COEFFICIENTS
Choice of:
National Defaults
City-Specific Defaults
User-Specified
| TCM PROGRAM-RELATED INPUT SCREENS |
SITE-SPECIFIC PROGRAMS
SITE ACCESS IMPROVEMENTS (NO TRANSIT)
Preferential Parking
Bicycle Lockers
New Transit Stops
FINANCIAL INCENTIVES & PARKING COSTS
Parking Cash-Out
Differential Parking Charges
Transit Incentives
SITE-SPECIFIC EM PLOVER SUPPORT PROGRAMS
On-site Transportation Coordinator
Ridematching
Outreach and Promotion to Employees
ALTERNATIVE WORK SCHEDULES
Flex-time
Compressed Schedules
Staggered Hours
Telework
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AREA-WIDE PROGRAMS
SITE ACCESS & TRANSIT SERVICE IMPROVEMENTS
Preferential Parking
Bicycle Lockers
New Transit Stops
More Frequent Transit Service
Faster Transit Service
FINANCIAL INCENTIVES & PARKING COSTS
Parking Cash-Out
Differential Parking Charges
Transit Incentives
AREA-WIDE EMPLOYER SUPPORT PROGRAMS
On-site Transportation Coordinator
Ridematching
Outreach and Promotion to Employees
Outreach and Promotion to Employers
ALTERNATIVE WORK SCHEDULES
Flex-time
Compressed Schedules
Staggered Hours
Telework
1
EMISSIONS-RELATED INPUT SCREENS
FLEET EMISSIONS INFORMATION |Oplional|
Inputs for Pre-Loaded MOBILE Factors
Inputs for User-Supplied MOBILE Factors
OTHER EMISSIONS-RELATED DATA (Optional)
Vehicle Fleet Mix
Affected Vehicle Speeds
VMT Mix by Facility Type
J
RESULTS SCREEN
RESULTS
Mode Shares & Changes
Trip Changes
VMT Changes
Emission Reductions:
HC (as VOCs|
CO
NOx
PM
C02
Air Toxics
15
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2.6 Can I save my inputs to use in another analysis?
Saving Scenarios - To make repeated use of COMMUTER quicker and easier, you can
save a complete set of analysis inputs and re-use them later as a template for evaluating
other scenarios. This avoids having to type in complete data from scratch for each
analysis, but still allows you to modify selected data to evaluate alternatives.
After inputting data for a specific analysis case, save the information to a "scenario file"
(indicated by a ".VME" file extension). First click on the "File" menu and select ".Save
Scenario." This will bring up a dialog box that allows you to save the file to disk for later
use. Click the arrow to the right of the "Save in" box to select the directory where you
want to save the file, then type a file name for the scenario to be saved in the "File name"
box, using the .VME suffix. (To make it easier to find and use your files, you may want
to save the ".VME" scenario files to the same folder or directory where the application
program was stored, e.g., C:\COMMUTER.)
Loading Saved Scenarios - When you want to load and re-use a saved scenario file, click
the "Load Scenario" item from the File menu. Then, select the directory and the specific
scenario file you saved earlier to be loaded into the application. Re-using existing
scenarios and making minor changes to their inputs is a more efficient way to create a
series of related scenarios than typing in all the data for each scenario.
Clearing Scenarios - If for some reason you have loaded a scenario or have typed in data
for all the input cells and want to delete the data from all the input cells and start over,
you can click the "Clear Scenario" item on the File menu. This initializes the program by
erasing the data currently contained in the input cells if you want to start re-entering all
new data without having to exit and reload COMMUTER. It does not delete saved
scenario files from your hard disk.
2.7 Can I use my own emission factors?
COMMUTER has been supplied with 192 sets of MOBILE6.2 emission factors that
encompass a range of input conditions throughout the country. Each of these supplied
data sets contains emission factors for six calendar years: 2007, 2009, 2010, 2013, 2019,
and 2021. Under general circumstances when COMMUTER is used as a screening
model, selecting the set of pre-loaded emission factors that best matches your local
conditions is adequate. However, if you want to use COMMUTER to produce emission
reductions reflecting local conditions, such as for SIP or conformity purposes, you must
use your own locally generated MOBILE6.2 emission factors to calculate emission
reductions in COMMUTER. The steps for using your own emission factors are
explained below.
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Step 1 - Create Properly Formatted Emission Factor Output File-Although you can
specify your exact local input conditions, your MOBILE6.2 output emission factors
must be generated in a specific format expected by COMMUTER. The sample
MOBILE6.2 template input file M6SAMPLE.IN, which is provided with the model,
identifies how specific commands in the MOBILE6.2 input file must be set to
produce output emission factors in the COMMUTER-required format. In addition, it
contains a series of 13 "Scenario" records that produce emission factors over a range
of speeds expected by COMMUTER. These scenario records can be edited to reflect
the altitude, calendar year, local ambient temperature, season of interest, and local
fuels data. In addition, the user may specify other locality-specific data in the "Run
Data" or "Scenario" sections, such as I/M programs, vehicle registration distributions,
or alternative Tier 2 phase-in schedules. Speed data files for each scenario are
provided with the model and should not be edited.
In addition, the user must specify the "database output" option with the formats
shown in the sample file. In addition, the user must specify calculation of particulates
as well as air toxics, as shown in the sample file, and provide the fuel parameters and
paniculate emission factor inputs in each scenario record, as required by MOBILE6.2
to calculate particulate and air toxics emissions. If these conventions are not
followed, the resulting MOBILE6.2 model output will not work properly with
COMMUTER.
IMPORTANT: Once you 've edited the 13 scenario records to
reflect your own altitude, temperature, and season inputs, you can
copy and paste this block of records to create emission factors for
multiple calendar years.
Once you have set up your MOBILE6.2 input file as described above and in
accordance with the required database output options, run MOBILE6.2. You can
name the MOBILE6.2 input and output files as you choose.
Step 2 - Process MOBILE6.2 Output - Once you have run MOBILE6.2, an
intermediate step is required to process MOBILE6.2 database-format output into the
format expected by COMMUTER. You can run this step from inside the
COMMUTER model using the "Process MOBILE6.2 Output" command from the
"File" menu. This command will allow you to browse for and select a standard
MOBILE6.2 database output file (.TB1) extension. It will then convert the data in
this file into a text file suitable for import into COMMUTER, with a .TBZ extension.
Note that corresponding toxics and PM MOBILE6.2 output files are also read (.TOX
17
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and .PM extensions, respectively), and a corresponding VMT file (.VMT) is also
generated that contains VMT fractions by vehicle type and facility type. The model
user must retain these files in the same directory as the .TB1 and .TBZ files and
should not delete them. The routine to process MOBILE output may take a few
minutes to run; this is normal.
Step 3 - Activate User-Supplied Emission Factors Option - On the "Fleet Emissions
Information" input screen in COMMUTER, you have the option of selecting
"User-Supplied Emission Factors." Once you have selected this option and specified
a calendar year, you will be reminded to Import User Emission Factors, as described
below. It is important that the calendar year you have specified match one of the
calendar years included in the .TBZ file you select.
Step 4 - Import User Emission Factors - Once you have generated a .TBZ file, you
can import this file into the COMMUTER model using the "Import User Emission
Factors" command from the "File" menu. This command will allow you to browse
for and select a .TBZ file. You may select any .TBZ file that you already have
generated from MOBILE6.2 output, without re-running the "process MOBILE6.2
output" routine described above. Importing the .TBZ file will take a few seconds;
you will be notified when the import routine has been successfully completed. These
emission factors will be saved within the COMMUTER model until you import a
different set of either user-specified or default scenario emission factors.
2.8 How do I view the results?
Once you have provided all of the required inputs (or selected default values),
COMMUTER will automatically calculate TCM travel impacts and, if you've entered
emission factor inputs, emission reductions. To view the results, all you need to do is
simply click either of the two command items on the Results menu. "View Travel
Results" displays travel impacts only. "View Travel and Emission Results" shows both
travel impacts and emission reductions (assuming you've entered emission factor inputs).
You can then scroll down the tabular summary to see the calculated results. Key outputs
include the following:
Baseline and final mode shares for each mode, including percent of trips
eliminated and change in mode share (final minus baseline);
Percent of trips shifted from the peak to off-peak period;
Baseline and final peak, off-peak and daily VMT;
18
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Baseline and final peak, off-peak and daily vehicle trips; and
Change in total daily emissions for each pollutant in tons per day and/or pounds
per day.
NOTE: If you did not enter all of the necessary input data, an
"Incomplete or Inconsistent Input" message box will be displayed
when the View Travel Results or View Travel and Emission Results
buttons are clicked. The message box indicates which data must
still be entered. If you click the OK button in the message box, the
program will activate the first entry screen and cell for which
missing or invalid data were detected.
To return to an input screen after viewing the results calculated by COMMUTER, simply
click the appropriate item in the Edit Inputs menu at the top of the application window.
2.9 How do I print my data and results?
For each scenario you evaluate, you can print both the detailed input data and the
tabulated emission reductions. To do this, click the File menu. Then select "Print
Inputs" from the drop-down menu to print a detailed listing of all program inputs. Select
either "Print Travel Results" or "Print Travel and Emission Results" from the File menu
to print a one-page output report showing travel impacts or travel impacts and emission
reductions, respectively.
Figure 4 shows the layout of a sample output report. General scenario information and
the specific TCMs evaluated are listed at the top of the report. Included in these items are
boxes that indicate whether you have supplied your own final mode shares and emission
factors. Below these items, summaries of the combined mode share impacts and travel
and emission reductions from baseline levels for all the TCMs selected are presented. As
noted in the table headers, travel and emission reductions are shown as positive numbers.
19
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Figure 4
Sa
COMMUTER MODEL RESULTS
SCENARIO INFORMATION
Description
Scenario Filename
Emission Factor File
Performing Agency
Analyst
Metropolitan Area
Area Size
Analysis Scope
PROGRAMS EVALUATED
n
Site Walk Access Improvements
Transit Service Improvements
Financial Incentives
Employer Support Programs
Alternative Work Schedules
User-Supplied Final Mode Shares
mp
le
Ou
tp
ut
Re
po
rt
MODE SHARE IMPACTS
TRAVEL IMPACTS (relative to affected employment)
Mode
Drive Alone
Carpool
Vanpool
Transit
Bicycle
Pedestrian
Other
No Trip
Total
Baseline
Final
%Change
Quantity
Baseline VMT
Final VMT
VMT Reduction
% VMT Reduction
Baseline Trips
Final Trips
Trip Reduction
% Trip Reduction
Peak
Off-Peak
Total
[Shifted from Peak to Off-Peak
EMISSION REDUCTIONS (positive values are decreases)
Ibs/day:
Pollutant
HC
CO
NOx
PM2.5
Toxics
Acetaldehyde
Acrolein
Benzene
1 , 3-Butadiene
Formaldehyde
MTBE
CO2
Peak
Off-Peak
Total
tons/day:
Pollutant
HC
CO
NOx
C02
Peak
Off-Peak
Total
20
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CAUTION: The program allows you to set up a scenario and
produce results for an individual TCM (as opposed to a
combination of measures). However, summing the results for
measures evaluated individually will not give you an accurate
representation of the true impact of a combination of measures.
2.10 Can I tell the model to remember where my files are stored?
Depending on how you launch COMMUTER (see Section 2.2), your "default" directory
(the directory pointed to when you open or save files) may not be the same as the
directory that the model and scenario files are stored in. You can tell the model where to
look for your scenario (and emission factor) files so you don't have to click out of the
"system" default directory (e.g., C:\My Documents) each time you want to open or save a
scenario.
To set your default or "working" directory when you're running COMMUTER, click
"Set Working Directory" from the File menu. The first time you do this, COMMUTER
will report that the working directory is blank as shown below.
VIEW/SET WORKING DIRECTORY
The current COMMUTER model working directory is ". Do you want to change it?
Yes || No I
This is normal. Simply click the "Yes" button. Another window, shown below, will be
displayed that then allows you to enter the disk drive and directory path where you've
installed COMMUTER (e.g., C:\COMMUTER).
SET WORKING DIRECTORY
Enter working directory for COMMUTER model files
OK
Cancel
C:\COMMUTE B|
21
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Once you have set the working directory, COMMUTER remembers that location and
uses it each time you open or save scenario files or import your own emission factors,
even if you exit and then re-run the model.
2.11 What do I do when I'm finished?
Before exiting COMMUTER, be sure you have saved the current inputs in a scenario file,
as described above, if you plan to re-use them later. When you have completed your
analysis session and want to exit COMMUTER, click "Exit Program" from the File
menu. The application will then close and exit.
22
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3. GENERAL INPUT SCREENS
This and the following two sections guide you step-by-step through the data that must be
provided in each of the input screens. This section covers the first three screens, which
you use to input general information; Section 4 explains the five input screens that are
specific to individual TCMs being analyzed; and Section 5 discusses the two screens you
will use to enter information required to calculate emission reductions. Each subsection
within these sections corresponds to one of the program's ten input screens. These have
been ordered in the sequence in which you would generally enter data for an analysis. To
make it easier to find information on specific data inputs, fields have been noted in bold,
underlined text
3.1 Scenario Information
Scenario information describes the area you are analyzing and the broad types of
commuter choice programs to be analyzed. Figure 5 displays the layout of the Scenario
Information screen. Key data items are explained below.
Metropolitan Area Size - This is where you define the size of the metropolitan area you
are analyzing, using the following categories:
Large - more than 2,000,000 in population;
Medium - 750,000 to 2,000,000 in population; and
Small - less than 750,000 in population.
Based on the area size you select, the program will retrieve default travel speeds. You
have the option to override the default speeds in the "Edit Emissions Data" screen with
values you obtain for your city.
Analysis Scope - The actual analysis can apply to any geographic level. However, you
must define the scope of your analysis as being area-wide ("1") or site-specific ("2").
23
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Figure 5
Scenario Information Input Screen
Field
SCENARIO INFORMATION
Data
Notes
Scenario Information
Scenario Filename
User EFs Filename
Description
General Information
Performing Agency
Address
Analyst
Metropolitan Area
Metropolitan Area Size
Filename of scenario stored on disk
User-supplied MOBILE emission factors (if used)
Title to further identify the scenario (optional)
Name of your organization (optional)
Address of your organization (optional)
Your name (optional)
Name of city/area being modeled (optional)
1 = Large (Over 2 million) 2 = Medium (750,000
to 2 million) 3 = Small (Under 750,000)
Metropolitan Area Size is a required input. The program retrieves default freeway and arterial travel speeds for the
area size input by the user. However, these defaults for Large, Medium and Small metropolitan areas may not be
as accurate as locally-derived travel speed data. These default travel speeds can be overridden in the "Edit Other
Emissions-Related Data" screen.
Definition of Analysis Area
Analysis Scope
Analysis Area/Site
Analysis Area Type
1 = Area-Wide (Metropolitan Area, County, etc) 2
= Site or Employer-Based
Name of analysis area evaluated (optional)
1 = CBD (Central Business District) 2 = Other
High-Density Commercial 3 = Other
The COMMUTER model can be used to evaluate commuter choice programs on both an urban area-wide and
individual employer (or site-specific) basis. The Analysis Scope input controls whether the model calculates area-
wide or site-specific impacts of commuter choice programs.
Employment in Analysis Area
Office Employment
Non-Office Employment
Total Employment
Refers to "traditional" professional office space
employment
Manufacturing, warehousing, retail, medical,
educational, entertainment and other employment-
generating land uses
The COMMUTER model may generate abnormally large mode shifts under a regional or area-wide analysis
scenario if realistic limits are not applied in estimating the affected employment input above. For site-specific
analysis, enter the employment of the workplace being analyzed. For area-wide analysis, the user is encouraged to
consult Section 3.1 of the COM M UTER Model User Manual for more detailed guidance on estimating affected
employment inputs for region being modeled.
Programs (Mark All Programs Being Analyzed with an "X")
1. Site Walk Access Improvements
2. Transit Service Improvements
3. Financial Incentives
4. Employer Support Programs
5. Alternative Work Schedules
Includes preferential parking, improved access to
transit
Includes more frequent and/or faster transit
service
Includes parking costs, transit fare/pass
subsidies, or other financial incentives
Includes support programs for carpooling,
vanpooling, transit, and/or bicycling
Includes flex time, telecommuting, staggered work
hours, and/or compressed work weeks
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An area-wide analysis evaluates TCM programs for a geographic area such as traffic
corridors, subareas (for example, the central business district), activity centers (for
example, a large office park complex), or the entire metropolitan region. A site-specific
analysis evaluates TCM programs applied only to a single business or employer location.
This option can be used when considering either a single place of business for a given
employer or a mixed use or multi-purpose place of business for a given employer or
employers. If you are an individual employer using this model to evaluate a company
employer support program, you should use the "site-specific " analysis.
As discussed in Sections 4.3 and 4.4, you will later be asked for further data that are
related to the scope you select. For example, if you specify "area-wide," some screens
will ask you to specify the percentage of employers in the area participating in the
program. If "site-specific" is specified, this percentage will be assumed to be 100
percent. (See Sections 4.3 and 4.4 for detailed instructions for inputting data for both
area-wide and site-specific analysis.)
Affected Employment in Analysis Area - The impact or applicability of various
programs and strategies is affected by type of employees in an area, which COMMUTER
defines according to the land use category of the employer. "Office" employees are those
working in land use categories that include traditional professional office space.
"Non-office" employees include those working in manufacturing, warehousing, retail,
medical, educational, entertainment, and other employment-generating land use activities.
You will be asked to enter both the number of office and non-office employees in the area
or at the target site that can be affected by the TCM programs being modeled. "Affected"
is the keyword in understanding what employment levels you should input here and
depends on whether you are performing a site-specific or area-wide analysis, as explained
below.
Site-Specific Affected Employment - If you are performing a site-specific or "single
employer" analysis (specified by choosing "2" for Analysis Scope), the employment
levels you enter should be the total of all employees that are eligible for, or exposed to,
any or all of the TCM programs you are evaluating. Most of the time, site-specific
affected employment will be the total employment level at the site. In rare cases where
employer support, financial incentive, or alternate work schedule programs being
evaluated would only be made available to a portion of all employees, enter that portion
as the affected employment.
Area-Wide Affected Employment - In an area-wide analysis, affected employment should
not be entered as the total employment in the area being considered. You must estimate
that subset of the total area employment that will be potentially affected by any or all of
the specific TCM programs you are evaluating.
25
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CAUTION: For area-wide analysis, you should not enter the total
employment in the analysis area. You do not want to base the
analysis on the total employment in the analysis area because
COMMUTER will then generate unrealistically high results for
regional scenarios. For example, the number of trips being shifted
from one mode of travel to another if all employees for a given
region are assumed to participate in a voluntary program would be
too high.
Steps to help you calculate the number of employees that can be affected by the TCM
programs you are evaluating under an area-wide analysis are listed below.
1. First, identify the portion of regional employers (and number of employees) that are
currently participating in existing programs, and therefore should be excluded from
the analysis. You can obtain the percentages of employers (by size and type) from the
MPO responsible for transportation and emissions planning in the region. Using the
total number of employees for a region is not realistic.
2. Finally, determine that portion of employers of a specific size (based on their number
of employees) that will be subjected to, or encouraged to implement, the voluntary
programs being evaluated. This percentage will vary by MPO region and could
include either office or non-office employers with 1,000, 500, 250, or 100 employees.
3. Next, estimate the portion of employers of each type (office and non-office) who will
agree to participate in any of the TCM programs you are evaluating, which will
largely be voluntary in nature. This percentage will vary by MPO region and could
include office employers only or a combination of office and non-office employers.
The following example is provided to demonstrate how you should use this process to
determine the employment levels you need to enter under an area-wide analysis.
Assume total employees for Region X: 1,000,000 employees
1. Estimate portion of total employees currently
participating in existing TCM programs: 20% -200.000 employees
800,000 employees
2. Estimate portion of remaining employees by size of
employer targeted by your voluntary programs, using
26
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employers of 500+ employees in this example:
Office (500+ employers): 250,000 employees
Non-office (500+ employers): 50,000 employees
3. Determine portion of remaining employees based on
estimated percentage of employers willing to
participate in any of the modeled programs:
(In this example we'll assume 30% office and
10% non-office employer participation)
Office - 30% participation: 75,000 employees
Non-Office - 10% participation: 5,000 employees
Using this example, you would enter inputs of 75,000 and 5,000 employees for affected
office and non-office employment, respectively.
You should be careful in making assumptions about the number of affected employees in
each region. Each region is likely to be significantly different based on the current
participation in voluntary programs, employer and employee participation rates, and
regional employment characteristics.
As these steps and the example indicate, when inputting the "affected" employment under
an area-wide analysis, you should supply estimates of the number of office and non-office
employees that are eligible for participation in any of the specific TCM programs you are
evaluating.
NOTE: If you are evaluating a scenario that packages multiple
programs (e.g., site access improvements, transit improvements,
and financial incentives), individual "program " participation rates
can also be specified in subsequent input screens for each program.
You should not confuse these program-specific participation rates
with the employer participation percentage in any program used to
estimate affected employment inputs. The program-specific
participation rates in subsequently discussed input screens provide
you with a means to "weight" the participation of qU affected
employees within individual programs when analyzing scenarios
that combine multiple programs.
27
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Programs - In this section, you simply check off which types of TCM strategies or
programs are to be considered in the scenario being analyzed. There are five possible
choices, described below. You simply mark (with an "X") all of the programs being
analyzed; you do not have to select only one.
1. Site Walk Access Improvements - Includes preferential parking for employees
using carpool and/or vanpool programs and improved access to transit systems.
2. Transit Service Improvements - Includes more frequent and/or faster transit
service.
3. Financial Incentives - Includes any project or program that changes the out-of-
pocket cost of alternative travel modes relative to automobile travel. Examples
include transit fare/pass subsidies, parking costs, or other financial incentives.
4. Employer Support Programs - Includes support programs for carpooling,
vanpooling, transit, and/or bicycling that do not result in any changes in direct
travel time or cost changes. For example, employers might provide information
about ridesharing and transit opportunities, match employees with carpools or
vanpools, and offer guaranteed ride home programs.
5. Alternative Work Schedules - Includes flex time, telecommuting, staggered work
hours, and/or compressed work weeks.
NOTE: If you are planning to enter your own estimate of final mode
shares as described in the Local Data inputs in Section 3.2,
COMMUTER will ignore any TCM programs you check here. By
inputting your own final mode shares, you are bypassing
COMMUTER'S final mode share calculations that are based on
TCM screen inputs.
3.2 Local Data
Once you have provided the general information on the scenario you are analyzing, you
need to provide data on the existing travel behavior and characteristics of the area or site.
Because travel characteristics such as mode shares (for example, transit users) and
average travel distances can vary a great deal within a region, you should define separate
geographic areas that have distinct and more or less homogenous characteristics for
28
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analysis. For example, you may wish to conduct separate analyses for the central
business district (CBD) and for the non-CBD portions of a city.
Baseline (i.e., existing) travel data for the region of interest are entered in the Local Data
input screen, shown in Figure 6. Each of the data elements in this screen is discussed
following Figure 6.
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Figure 6
Local Data Input Screen
LOCAL DATA
Baseline (Existing)
Use Data
Default Local Default
Work-Trip Mode Shares
Auto - Drive Alone
Auto - Carpool
Vanpoo I
Transit
Bicycle
Walk
Other
Total
Work Trip Length (mi)
Average person-trip length
Average trip length -- vanpool
Average trip length -- bicycle
Average trip length -- walk
Vehicle Occupancy
Average Carpool Occupancy
Average Vanpool Occupancy
Length of Peak Period (hours)
Percent of Work Trips in Peak Periods
0.0%
78.2%
12.1%
0.5%
4.9%
0.4%
3.0%
0.8%
100.0%
Supply Final Mode Shares? [
12.2
20.4
2.9
0.9
7.2
3.0
61 .4%
Baseline mode share, trip length, average occupancy and peak period data representing local conditions are entered in this
input screen. From these inputs and data entered in the "Mode Choice Model Coefficients" screen, the COMMUTER model
internally calculates final mode shares and travel changes resulting from TCM programs selected. If you want to supply your
own estimates of final mode shares (such as might be obtained from employee survey data), mark the box labeled "Supply Final
Mode Shares" (with an "X"). When this option is selected, the COMMUTER model displays an additional series of input cells
below the box where final mode share inputs can be entered. Remember, these final mode shares should reflect work-trip
mode choice after implementation of the TCM programs you're currently analyzing and override the mode share calculations
made by the model.
The peak period includes the morning and evening time periods when highways are most congested. These periods may be
defined differently in different areas. For the default "percent of work trips in peak period" provided, the AM peak is defined as
6:00 to 9:00 AM and the PM peak as 4:00 to 7:00 PM. The same peak period should be used for reporting percent of work trips
in peak period and affected vehicle speeds (which are entered later in the "Other Emissions-Related Data" screen).
"Length of peak period" refers to the length (in hours) of the AM or PM peak period. If the AM and PM peak periods are different
lengths, this can be an average of the two lengths.
"Percent of work trips in peak period" should also be reported as an average for the AM and PM peak periods combined. For
example, assume there are 200,000 and 300,000 total vehicle trips in the AM and PM peak periods, respectively. If the number
of work trips are 150,000 in the AM peak and 250,000 in the PM peak, then the percentage of work trips in peak period is
(150,000 + 250,000) / (200,000 + 300,000) = 80%.
Existing Mode Shares, Trip Length, and Occupancy - If you are conducting a site-
specific analysis, you may be able to obtain data on existing employee mode shares from
employee surveys, if such surveys have been conducted. You can also enter local data on
trip lengths and average vehicle occupancy for carpools and vanpools if such data are
available.
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If you do not have specific data available, you should be able to obtain transportation data
for the city, metropolitan area as a whole, or other area of analysis from the regional
transportation planning agency. You should work with local or regional transportation
planners to identify the most appropriate data for the analysis.
If local data are not available, you may use the default parameters provided in the model.
These are shown in Figure 6 under the "Defaults" column. You should indicate which
default values to use by checking the appropriate box(es) on this screen.
User-Supplied Final Mode Shares - If you are performing an analysis where you have
estimates of "final" mode shares (after implementation of the TCMs being modeled), you
can enter these final mode share estimates in the Local Data screen. Under most
circumstances, you'll want to let COMMUTER calculate final mode shares based on the
inputs you supply in the TCM screens using the pivot-point methodology discussed in
Section 1.5. There may be certain situations where you want to enter your own estimate
of final mode shares, rather than using COMMUTER'S calculations. For example, when
you are performing a site-specific analysis for a company, you may have employee
survey data available that estimate how mode choice would change in response to a
particular program or programs.
For these situations, mark the "Supply Final Mode Shares?" box at the upper right of the
Local Data input screen. When you do, a series of cells appears below this box, allowing
you to enter final mode shares, reflecting changes from existing shares due to the TCM
programs you're modeling.
For example, suppose under existing conditions that "Company A" work-trip mode
shares were split at 80% Auto-Drive Alone and 20% Transit. Company A is considering
a program in which employees are offered a cash incentive to ride the bus and, from an
employee survey, determines that an additional 5% would accept the incentive and ride
the bus. The final mode shares are thus split as 75% Auto-Drive Alone and 25% Transit.
These values would be entered in the final mode share cells after you marked the "Supply
Final Mode Shares?" box.
NOTE: When you enter your own final mode shares in the Local
Data input screen as explained above, any TCM programs that
you've checked at the bottom of the Scenario Information screen
and inputs you've entered in those TCM-specific screens are
ignored. By entering your own final mode shares, you 're telling
COMMUTER not to use the TCM inputs to calculate final mode
shares.
-------
Under most circumstances, you won't know what the final mode shares will be as a result
of the TCM programs that you are analyzing. In these cases, leave the "Supply Final
Mode Shares?" box blank and allow COMMUTER to calculate final mode share from the
TCM program inputs you'll enter in subsequent input screens.
Length of Peak Period - The "peak period" includes the morning and evening time
periods when highways are most congested. These periods may be defined differently in
different areas. You should use the same peak period definition when reporting the
percent of work trips in a peak period that you use when reporting baseline travel speeds
(see below). You can obtain information on the peak period definition from
transportation planning staff at your regional transportation planning agency.
"Length of peak period" refers to the length (in hours) of the AM or PM peak period. If
the AM and PM peak periods are different lengths, you should use the average of the two.
Percent of Work Trips in Peak Periods - You need to enter the percent of trips during
the peak periods that are work-related, averaging the totals for the AM and PM peak
periods combined. For example, assume there are 200,000 and 300,000 total vehicle trips
in the AM and PM peak periods, respectively. If the number of work trips are 150,000 in
the AM peak and 250,000 in the PM peak, then the percentage of work trips in the peak
period is calculated as follows:
150,000 + 250,000
= 80/0
200,000 + 300,000
You should enter local or site-specific data if it is available, instead of relying on the
default value. The default value provided is based on the national percentage of all work
trips that occur in both the AM and PM peak periods. In this program, the default AM
peak is defined as 6:00 to 9:00 AM and the default PM peak as 4:00 to 7:00 PM.
3.3 Edit Coefficients
This screen allows you to enter locally available values for mode-choice travel time and
cost coefficients, rather than use the default values provided by the model. Figure 7
illustrates the layout of the Edit Coefficients screen.
Mode-choice coefficients are used within COMMUTER to compute changes in travel of
each commute mode (e.g., drive-alone, carpool, transit, walk, etc.) under Site Access or
Transit Improvement programs and Financial Incentive programs. These coefficients are
used in transportation models referred to as "logit mode-choice" models to represent the
willingness of commuters to use alternate modes of travel to driving alone when faced
32
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with changes in travel time or cost. (Please refer to the accompanying COMMUTER
Model Procedures Manual for detailed information on how mode-choice coefficients are
developed, tested and applied in transportation modeling.)
The travel and emission impacts calculated by COMMUTER are highly sensitive to the
values of these coefficients, especially the cost coefficients. It is strongly recommended
that you use local coefficients for mode choice, if available. Coefficients have been
estimated in many urban areas by the regional transportation planning agency (usually
MPOs, Councils of Government, or Associations of Governments). Values of travel time
and cost coefficients for many individual cities are incorporated into COMMUTER at the
bottom of this input screen. The values of these mode-choice coefficients are based on
the travel models currently used by regional transportation planning agencies. You are
encouraged to contact your local transportation planning agency to ensure the values cited
are up-to-date or to obtain coefficients for cities not listed in the table at the bottom of the
input screen.
If local mode choice model coefficients are not available for your city, you can use the
default values provided by the model (which are based on the "Metropolitan Area Size"
you specified in the Scenario Information screen; see Section 3.1). However, these
defaults will not represent mode choice behavior as accurately as actual local data.
33
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Figure 7
Edit Coefficients Input Screen
MODE CHOICE MODEL COEFFICIENTS
Check
DEFAULTS BY AREA SIZE
All Areas
IVTT (min)
All Modes
-0.0253
OVTT (min)
Walk Time
-0.0473
Transit
Wait
-0.0466
Cost (cents)
Auto -
Parking
-0.0056
Transit -
Fare
-0.0040
I | User-Specified
_L
J
ICoefficients Used: Boston
I -0.03141 -0.03301 -0.05501 -0.0173| -0.0083|
Mode choice model coefficients are entered in this screen. The program retrieves default coefficients based on national
average from numerous cities' models. However, these defaults are typically not as accurate as city-specific coefficients
developed for many communities across the country. City-specific coefficients for a number of cities based on a review of
current literature and existing travel demand models are provided for use within the model and can be viewed by scrolling down
below this help box. The user is encouraged to utilize these local coefficients for the specific city being modeled (if available) in
lieu of the defaults by simply checking the box next to the appropriate city. The user is also encouraged to contact their local
transportation planning agency to ensure the values cited are up-to-date or to obtain coefficients for cities not listed in these
tables.
When applying user-specified values, be aware that most models generally use input travel/wait time coefficients in MINUTES
and cost-related coefficients in CENTS. Mode choice models such as the TDM model then internally convert the values of
these coefficients to match the units of the travel/wait time or cost inputs. The COMMUTER model has also been programmed
to apply a conversion factor to the Auto Parking and Transit Fare cost coefficients (in cents) when used with financial incentive
inputs in units of DOLLARS per vehicle per day. When inputting your own coefficients, make sure the travel/wait time
coefficients are in MINUTES and the cost-related coefficients are in CENTS.
Note to previous COMMUTER users: In COMMUTER Version 2.0, metropolitan area size is no longer used to select the
default mode choice coefficients. A review of recently developed coefficients found that these coefficients do not show a
significant variation by area size.
.c
o
CITY-SPECIFIC DEFAULTS
City
Albuquerque
Atlanta
Baltimore
Boston
Chicago
Cleveland
Columbus
Dallas
Denver
Detroit
Houston
Los Angeles
Milwaukee
New York
Philadelphia
Phoenix
Portland
Reno
Sacramento
San Diego
San Francisco
San Juan
Santa Cruz
Seattle
Tucson
Washington D.C.
Year
1992
2002
1993
1991
1990
1994
1999
1996
1997
1996
1985
1996
1991
1996
1986
1991
1994
1991
2001
1995
1990
1990
1990
1990
2000
1994
IVTT
All Modes
-0.0209
-0.0256
-0.0300
-0.0314
-0.0282
-0.0178
-0.0213
-0.0544
-0.0180
-0.0512
-0.0220
-0.0450
-0.0157
-0.0113
-0.0391
-0.0167
-0.0394
-0.0275
-0.0250
-0.0250
-0.0333
-0.0366
-0.0163
-0.0176
-0.0178
-0.0300
OVTT
Walk Time
-0.0219
-0.0639
-0.0750
-0.0330
-0.0440
-0.0444
-0.0640
-0.0640
-0.0540
-0.0186
-0.0568
-0.1073
-0.0412
-0.0380
-0.0316
-0.0206
-0.0646
-0.0550
-0.0380
-0.0500
-0.0931
-0.0717
-0.0325
-0.0206
-0.0400
-0.0750
Transit
Wait
-0.0978
-0.0256
-0.0750
-0.0550
-0.0960
-0.0378
-0.0465
-0.0640
-0.0180
-0.0186
-0.0568
-0.0423
-0.0412
-0.0554
-0.0511
-0.0304
-0.0397
-0.0550
-0.0380
-0.0250
-0.0523
-0.0752
-0.0325
-0.0155
-0.0200
-0.0750
Cost
Auto -
Parking
-0.0031
-0.0031
-0.0043
-0.0173
-0.0021
-0.0034
-0.0016
-0.0056
-0.0014
-0.0041
-0.0154
-0.0025
-0.0045
-0.0004
-0.0026
-0.0053
-0.0135
-0.0167
-0.0026
-0.0069
-0.0021
-0.0066
-0.0045
-0.0024
-0.0018
-0.0043
Transit -
Fare
-0.0031
-0.0013
-0.0043
-0.0083
-0.0008
-0.0024
-0.0016
-0.0055
-0.0012
-0.0041
-0.0061
-0.0025
-0.0045
-0.0004
-0.0012
-0.0053
-0.0135
-0.0067
-0.0026
-0.0026
-0.0021
-0.0066
-0.0036
-0.0024
-0.0018
-0.0043
34
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4. TCM-SPECIFIC DATA
This section discusses the input screens that are used to enter TCM-specific data for each
of five different types of programs, with each program having its own input screen. As
explained in Section 2, programs can be analyzed individually or in combination.* At this
stage, you can edit any of the programs checked under "Programs Analyzed" on the
"Scenario Information" screen. (Remember, however, that if you did not select a
program from the Scenario Information screen, you will not have access to the data entry
screen for that program.)
4.1 Site Access and Transit Service Improvement Programs
This section describes the Site Access and Transit Service Improvement program inputs.
Figure 8 shows the single input screen used for these programs.
Site Access Improvements
Site access improvements include such things as preferential parking policies for carpools
and vanpools or improvements to the work site or area that make access to transit easier.
For example, parking spaces in close proximity to both office building locations and
transit station/transit center locations could be provided for ease of access and reduced
travel times for carpool and vanpool vehicles. These programs also include improved
pedestrian and bicycle infrastructure at transit locations to encourage transit usage. Along
with preferential parking spaces, infrastructure improvements could include secure
lockers and showers for pedestrians and bicyclists and improved access to transit facilities
from the adjacent roadway system.
Walk-Access Time - You will need to specify the change in "walk access time," which is
the time required to walk from the parking space or transit stop to the work site. A
decrease in walk access time for any particular travel mode is represented as a negative
value.
As noted in Section 2, however, you will not obtain accurate results by analyzing individual measures and
then summing the results. Measures that may be implemented together should be analyzed together.
35
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Figure 8
Site Access & Transit Improvements Input Screen
SITE ACCESS & TRANSIT SERVICE IMPROVEMENTS
I. Site Access Improvements
Mode:
Drive Alone
Carpool
Vanpool
Transit
Bicycle
Pedestrian
Change in
Walk Access
Time (min)
[Employer Participation Rate: |
"Change in Walk Access Time" represents the difference in walking time associated with travel to or from the workplace
as a result of worksite access changes. Walking time includes the time taken to walk from a parking lot or a bus stop to
the actual worksite. Walk access time can be affected through policies such as preferential parking for carpools and
vanpools or through improvements to the worksite or area which make access to transit easier. A decrease in walk
access time for any particular mode should be entered as a negative value.
"Employer participation rate" refers to the percent of employers in the analysis area implementing the walk access
improvements. (This option is not necessary for site-specific analysis because the "participation rate" is 100%.)
II. Transit Service Improvements
Ma. More Frequent Service
Change in avg. headway (min)
Employment Served (% of area)
Mb. Faster Service
Change in route travel time (min)
Employment Served (% of area)
Transit Operating Data
Increase in daily VMT by Transit
Vehicles
Average speed of affected transit
vehicles (mph)
Default average speed
Check here to use default transit
speed
14.8
"Change in average headway refers to the average change in frequency of service for transit service to the employment
center or analysis area. An increase in service frequency is entered as a negative number. For example, if peak period
transit service frequency increases from 20-minute to 15-minute intervals, the change in average headway would be
entered as "-5.0".
"Change in route travel time" refers to the average change in total route travel time for all transit service to the area. A
decrease in travel time is entered as a negative number. For example, if new express bus service decreases the overall
route travel time by 5 minutes, this would be entered as "-5.0".
"Employment served" refers to the percent of employment in the analysis area which is served by the improved transit
service. (This option is not available for site-specific analysis).
"Increase in daily VMT by transit vehicles" refers to the additional transit vehicle-miles of travel as a result of the
improved transit service. Refer to Section 4.1 of the COMMUTER Model User Manual for guidance on how to calculate
this parameter.
36
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Employer Participation Rate - If you specified an area-wide analysis scope, you will
also need to specify the percent of employers in the analysis area implementing the walk-
access improvements.
Remember, as discussed in Section 3.1, that there are two types of participation rates you
need to consider in setting up the inputs to COMMUTER. The first type is used in
estimating the affected employment inputs and refers to participation in any of the TCM
programs being modeled. The second type, the individual program participation rates,
are actual model inputs, and are used to further restrict the "eligibility" of all affected
employment to individual programs, such as Site Access Improvement programs. Thus,
in an area-wide analysis assuming 100,000 affected employees, a 15% Employer
Participation Rate for Site Access Improvement programs instructs COMMUTER that
15,000 employees (100,000 x 15%) are eligible or affected by site access improvement
strategies. (Note that the model assumes a proportional ratio of employers to employees
in determining affected employment for individual programs.)
The employer participation rate is not used in site-specific analysis because it is assumed
to be 100%.
Transit Service Improvements
Transit service improvements may include providing more frequent bus or shuttle service
to work sites, as well as providing faster transit service through express routes or
operational improvements. These improvements may also include implementing new
route services resulting from the transit planning process.
If you are analyzing improvements that lead to more frequent service, you will need to
enter the "Change in Average Headway." This refers to the average change in the
frequency of transit service to the employment center or analysis area. An increase in
service frequency is entered as a negative number. For example, if peak period transit
service frequency increases from every 20 minutes to every 15 minutes, the change in
average headway would be represented as -5.0 minutes.
"Employment Served" refers to the percent of employment in the analysis area that is
served by the improved transit service. As with the Employment Participation Rate input
for Site Access Improvement programs, Employment Served should reflect the fraction of
all affected employment that are exposed to the transit improvements. As an example,
expanding transit service along a single network corridor would affect only the fraction of
employment served by this transit corridor. Again, you do not need to enter this input if
you are conducting a site-specific analysis.
37
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If you are evaluating faster service improvements, you will need to enter the "Change in
Route Travel Time " This refers to the average change in the time required to travel the
total route for all transit service to the area. A decrease in travel time is represented as a
negative number. For example, if new express bus service decreases the overall route
travel time by 5 minutes, this would be represented as -5.0 minutes.
If transit service improvements are implemented, the change in daily transit vehicle-
miles as a result of increased service must also be considered. For this, you will need to
estimate the following items:
The number of additional daily bus-trips on each route, for routes on which
service is increased; and
The total round-trip route length for each route on which service is increased.
You should be able to obtain information on route-mileage increases from the local
transit agency or you can develop estimates from operating plans for the proposed transit
service. Estimates of daily mileage increases should take into consideration the distance
traveled to and from the storage/maintenance facility to the beginning/end of the route.
In addition, an average travel speed for the affected transit service should be estimated.
This can be done by dividing the total length of each affected route by the time taken to
complete the route.
If transit service improvements are implemented, the change in daily transit vehicle-miles
as a result of increased service must also be considered. This requires estimating the
following items:
The number of additional daily bus-trips on each route, for routes on which
service is increased; and
The total round-trip route length for each route on which service is increased.
Information on route-mileage increases can be obtained from the local transit agency or
can be estimated from operating plans for the proposed transit service. Estimates of daily
mileage increases should take into consideration the distance traveled to and from the
storage/maintenance facility to the beginning/end of the route.
In addition, an average travel speed for the affected transit service should be estimated.
This can be done by dividing the total length of each affected route by the time taken to
complete the route.
38
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4.2 Financial Incentive and Parking Cost Programs
Financial incentives include any policies that affect how much it costs to travel via a
particular mode. Some examples of financial incentives are listed below.
Increased parking charges, especially for single-occupant vehicles.
Reduced parking fees for carpools and vanpools.
Transit subsidies such as free monthly passes.
Parking cash-out programs.
The Financial Incentive and Parking Cost program input screen is shown in Figure 9. A
decrease in cost (i.e., an incentive) is entered as a negative number. Changes in parking
cost are entered on a per-vehicle basis. Changes in other fare costs and other financial
costs are entered based on the change in cost per person per day (i.e., round trip transit
fare).
Figure 9
Financial Incentives Input Screen
FINANCIAL INCENTIVES AND PARKING COSTS
Mode:
Drive Alone
Carpool
Vanpool
Transit
Bicycle
Pedestrian
Change In Daily Cost:
Parking Cost
($/vehicle)
Employer
Participation Rate:
Fare Cost ($/
person/RT)
Other
Financial
Cost ($/
person/RT)
Total Change
($/
person/RT)
$
$
$
$
$
$
"Financial incentives and parking costs" may include higher parking charges for single-occupant vehicles, reduced
parking fees for carpools or vanpools, transit subsidies such as free monthly passes, or other financial incentives for
specific modes. A decrease in cost is entered as a negative number. For example, provision of a transit pass valued
at $30 a month would be entered as a change in fare cost of -$1 .50 ($30 / 20 days). The cost change inputs are
entered on a daily basis.
"Employer participation rate" refers to the percent of employers in the analysis area offering these incentives to their
employees. (This option is not required for site-specific analysis because the "participation rate" is 100%.)
39
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As in other screens, "Employer Participation Rate" refers to the fraction of all affected
employees being offered financial incentives on a percent-of-employers basis. Like the
other program-specific "employer participation rate" inputs, COMMUTER applies the
proportion of participating employers to determine the fraction of all affected employees
being offered financial incentives. It is not used for site-specific analysis.
Two examples are provided below to illustrate how the financial costs should be
calculated and entered.
Sample Calculations for Financial Incentives and Parking Cost Programs:
If parking costs are increased by $2.00 per day for all types of vehicles, you
would enter +$2.00 for Auto-Drive Alone, Carpool, and Vanpool. (The model
will convert the costs per vehicle to the costs per person by dividing by the
assumed average vehicle occupancy as identified in "Local Data.")
If a transit pass worth $30 per month is provided, you would enter a change in
fare cost of -$1.50 ($30 divided by 20 days per month).
Note that you enter these cost inputs in dollars per vehicle per day. COMMUTER
internally converts the Parking Cost and Transit Fare mode-choice coefficients that you
entered in units of cents in the "Edit Coefficients" screen into dollar units before
combining them with the cost inputs entered in this screen in the mode share calculations.
Parking Cash-Out Programs - Parking cash-out programs are modeled in this input screen
by treating the cash-out payment as a "subsidy" for use of eligible alternative modes. For
example, if the cash value of the parking subsidy were $60 per month or $2 per day, a
current Single Occupant Vehicle (SOV) user would see no difference in his/her cost to
drive (park), but the transit user would suddenly find it $2 per day cheaper to use transit.
The same logic applies to all modes that are eligible alternatives, i.e., bike, walk, or
ridesharing (if there is no problem with the cash-out recipient still parking at the site as a
carpooler/vanpooler). In this example, you would enter -$2 in the "Transit" row and
"Parking Cost" column.
So to handle cash-out programs in COMMUTER, you enter nothing for the SOV mode
parking cost, and enter a subsidy for each of the eligible alternative modes. Note that in
the rideshare case, each passenger receives the full value of the subsidy, unlike where you
give a parking discount to carpools and the savings is split among the number of
occupants.
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4.3 Site-Specific Employer Support Programs
There are a number of strategies that employers can use that reduce the number of people
commuting to work in single-occupancy vehicles (SOVs), but do not result in measurable
changes in the time or cost of traveling to work. Research suggests that such "soft"
incentives or support programs can change travel behavior by providing encouragement
to use other modes of travel, informing travelers of alternatives, or removing
impediments. Examples of this type of strategy include selling transit passes at the work
site, providing rideshare matches, marketing and promoting alternative modes, providing
a guaranteed ride home program, forming and supporting a vanpool, and providing
preferential parking for carpools. (Note that these types of programs also apply for an
area-wide analysis, discussed in Section 4.4.)
Figure 10 shows the input screen for site-specific analysis of employer support programs.
As shown in the figure, the first thing you need to do is specify the entry format which
refers to the type of data you will be entering.
For a site-based analysis, it is recommended that you specify existing and proposed
program levels. These refer to the general level of effort spent on the program (which
affects its effectiveness) and are explained below, along with the codes used for data
entry. They are defined separately for carpooling, vanpooling, transit, and bicycle
commuting.
As an alternative, you can specify the expected mode share increase. This expected
increase in each mode of travel is added to the baseline mode share that was specified in
the input data.
CAUTION: You should not, use this alternative entry option unless
you have good data indicating that a proposed program will lead
to a likely mode share increase. If you do specify a mode share
increase, you should document existing support programs and the
programs to be implemented, along with survey or other data that
were used to estimate the mode share increase.
41
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Figure 10
Site-Specific Employer Support Programs Input Screen
EMPLOYER SUPPORT PROGRAMS FOR ALTERNATIVE MODES
SITE-SPECIFIC ANALYSIS
Entry Format (check one only):
BSpecify Program Level
Specify Mode Share Increase
Specify Program Level:
'Program Level" and "Mode Share Increase" input options are mutually
exclusive. You enter input data for either one or the other based on which
Entry Format box you check to the left. See the help box below for an
explanation of each input.
Program
Carpool
Vanpool
Transit
Bicycle
Existing
New
Specify Mode Share Increase:
Program
Carpool
Vanpool
Transit
Bicycle
Existing
0.0%
0.0%
0.0%
0.0%
Increase
New
0.0%
0.0%
0.0%
0.0%
"Employer Support Programs" include programs such as provision for an on-site transportation coordinator, ridematching,
transit information, and other actions aside from time and cost incentives which encourage employees to utilize alternative
modes. Two entry options are available for site-specific analysis:
(1) Specify existing and new program levels for Carpool, Vanpool, Transit, and Bicycle program support. A program level
of "0" represents no program. Program levels of "1" through "4" indicate varying levels of effort for the programs. These
program levels are described in Section 4.3 of the COMMUTER Model User Manual.
(2) Specify an expected mode share increase for each mode. This increase is added to the baseline mode share as
specified in the input data.
IMPORTANT: Entry option (2) should only be utilized if the user has evidence, such as survey data, suggesting a likely
mode share increase as a result of proposed programs. If a mode share increase is specified, the user should document
existing support programs and programs to be implemented, along with survey or other data indicating the basis for the
mode share increase estimates.
Definition of Program Levels
The impact of employer support programs and strategies varies depending on the level of
effort expended on the program. The level of program effort is a particularly important
data input because it defines what is actually meant by, for example, a "carpool support"
program. The program level can vary from 0 to 4, with 0 representing no program and 4
representing a program of maximum effort. (These program level definitions will also
apply for area-wide analyses, as discussed in Section 4.4.) The following program level
descriptions are not requirements for each level, but are intended as suggested guidelines
to help you assign a level designation to the support activities you are trying to model.
42
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Note that preferential parking or direct financial incentives to employees offered as part
of a support program should be captured on the Site Access and Transit Service
Improvement input screen, and the Financial Incentives and Parking Costs input screen,
respectively. They should not be considered in the determination of program support
level.
Carpool Support Programs
Level 0 - no program
Level 1 - includes carpool information activities (tied in with area-wide matching)
and a quarter-time transportation coordinator.
Level 2 - includes an in-house carpool matching service and/or personalized
carpool candidate get-togethers (including information activities) and a quarter-
time transportation coordinator.
Level 3 - includes in-house carpool matching and information services plus
preferential (reserved, inside, and/or especially convenient) parking for carpools, a
policy of flexible work schedules* to accommodate carpools, and a half-time
transportation coordinator.
Level 4 - includes in-house carpool matching and information services plus
preferential parking for carpools, flexible work schedules, and a full-time
transportation coordinator.
Vanpool Support Programs
Level 0 - no program
Level 1 - includes vanpool information activities (tied in with area-wide vanpool
matching and/or third-part vanpool programs), plus a quarter-time
transportation coordinator.
Level 2 - includes in-house vanpool matching services and/or personalized vanpool
candidate get-togethers, and non-monetary vanpool development, plus a
quarter-time transportation coordinator and a policy of flexible work
schedules.
Flexible work schedules as defined under these support programs refers to providing latitude to employees
to accommodate slight variations in arrival/departure to participate in these programs. This differs from a
formal Flex-Time policy, which is defined and discussed later in Section 4.5.
43
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Level 3 - includes in-house vanpool matching services; vanpool development and
operating assistance, including financial assistance, such as vanpool
purchase loan guarantees, consolidated purchase of insurance, and a
startup subsidy (generally, at least two forms of such financial assistance
should be included); and additional services such as van washing and
preferential (reserved, inside, and/or especially convenient) parking for
vanpools, plus a half-time transportation coordinator.
Level 4 - includes in-house vanpool matching services; vanpool development and
operating assistance, including major financial assistance, such as
employer purchase of vans with favorable leaseback (or alternative
continuing subsidy, such as free maintenance, free insurance, and/or
direct subsidy to keep vanpool fares low) in addition to startup subsidy;
several additional incentives such as van washing, preferential parking for
vanpools, guaranteed ride home, and a full-time transportation
coordinator and/or personalized vanpool candidate get-togethers.
Transit Support Programs
Level 0 - no program
Level 1 - includes a transit information center plus a quarter-time transportation
coordinator.
Level 2 - includes a transit information center and a policy of work hours
flexibility to accommodate transit schedules/delays, plus a quarter-time
transportation coordinator.
Level 3 - includes a transit information center and a policy of work hours
flexibility, on-site transit pass sales, plus a half-time transportation
coordinator.
Level 4 - includes a transit information center and a policy of work hours
flexibility, on-site transit pass sales, guaranteed ride home, and a
full-time transportation coordinator.
Bicycle Support Programs
Level 0 - no program
Level 1 - providing on-site bicycle parking (racks or lockers).
44
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Level 2 - providing bicycle parking (racks or lockers) and shower facilities.
Level 3 - providing secure bicycle parking (storage lockers or indoor storage) and
shower facilities, in conjunction with local infrastructure conducive to
bicycling. This includes the presence of (a) off-street bike paths, (b) on-
street bike lanes, and/or (c) local streets with light traffic by which
cyclists can access the workplace.
Level 4 - providing parking, shower, and infrastructure conditions as for Level 3,
and also sponsoring workplace promotional activities. These activities
should include promoting bicycle commuting, identifying the availability
and location of parking and shower facilities, and providing local bicycle
route maps, along with other activities to encourage bicycle commuting.
Some employer support programs may have combinations of characteristics different than
those shown here. In this case, you should choose the program level that most closely
represents the actual program being implemented.
If there is no program level that you feel most closely represents the combination
program being offered, you can specify "combinations" of program levels by running the
program for an area-wide rather than site-specific analysis. For example, if a carpool
program includes all the elements of a Level 3 program except for flexible work
schedules, you may want to model this program as halfway between Level 2 and Level 3
in terms of effectiveness. You can do this by setting the analysis scope to "Area-Wide"
and specifying that 50 percent of employers have a Level 2 program and 50 percent have
a Level 3 program. Note that if you set the employer participation rate at 100 percent for
every program being tested, the area-wide and site-specific analyses will give identical
results.
4.4 Area-Wide Employer Support Programs
The discussion in Section 4.3 of the types of employer support programs that may be
offered also applies here. Although different input formats are used for site-specific and
area-wide employer support programs, the data elements themselves are similar.
Figure 11 shows the input screen for area-wide analysis of employer support programs.
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Figure 11
Area-Wide Employer Support Programs Input Screen
EMPLOYER SUPPORT PROGRAMS FOR ALTERNATIVE MODES
AREA-WIDE ANALYSIS
Percent of Employers Participating
Program None
Carpool 100%
Vanpool 100%
Transit 100%
Bicycle 100%
Percent of Employers Participating
Program None
Carpool 100%
Vanpool 100%
Transit 100%
Bicycle 100%
-- Existing
Program Level
1234
New
Program Level
1234
Total
100%
100%
100%
100%
Total
100%
100%
100%
100%
"Employer Support Programs" include programs such as provision of an on-site transportation coordinator,
ridematching, transit information, and other actions aside from time and cost incentives which encourage employees to
utilize alternative modes.
For an area-wide analysis, the analyst should specify both existing and new (expected) participation rates (percent of
employers participating) by program level for each mode. Program levels of "1" through "4" indicate varying levels of
effort for the programs which are described in Section 4.4 of the COMMUTER Model User Manual.
You should use the definitions of support program levels given in Section 4.3 for area-
wide analyses also. Be sure to read these definitions before proceeding.
For area-wide analysis of employer support programs, you must specify the percent of
employers participating in each of the program levels and modes. For each mode
(carpool, vanpool, transit, and bicycle), you need to enter the percent of employers in the
area participating at each program level. The sum of Levels 0 through 4 for each mode
should equal 100%. Employers who are not participating in any program would be
included in the "Level 0" program level. Participation rates should be specified for both
the base case (existing conditions) and the proposed program levels being evaluated.
4.5 Alternative Work Schedule Programs
This class of commuter-related TCM strategies is aimed at reducing how often commute
trips are made or shifting the timing of the trip out of the peak hour. For example, flex-
time and staggered work hour strategies have the effect of merely shifting commute travel
to a less-congested time period. These strategies will not affect the number of overall
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trips or the amount of VMT, but they will change the distribution of trips, VMT, and
emissions between the peak and off-peak time periods. They may also affect overall
emissions slightly by affecting the average speed in the peak and off-peak periods.
Definitions of the various work schedule programs and their likely impacts are discussed
later in this section.
Figure 12 shows the input screen for entering information on alternative work schedules
and telecommuting programs. As shown, you will first need to choose an entry format
option, as explained below:
Eligibility Rate - This indicates the percent of all employees in the analysis
system* who are offered the program. The model then applies an assumed
participation rate to the total number of employees that are eligible. Note that the
employees eligible for each alternative work schedule and those not eligible for
any strategy must sum to 100 percent. In other words, only one alternative work
schedule strategy may be offered to an employee at a time. This simplifying
assumption is used in the manual and spreadsheet model because employees are
unlikely to combine more than one alternative work strategy at a time (for
example, those employees working a compressed work week are unlikely to be
allowed to telecommute on regularly scheduled work days). This parameter
relates mainly to the logic of applying this strategy to different employment
segments. For example, manufacturing or retail employees are not reasonable
candidates for participation in telecommuting programs. You should consider the
characteristics of the employment base you are analyzing when determining the
value to use for this parameter.
Participation Rate - As an alternative, you can specify existing and expected
actual participation rates for each program. If you do specify the participation
rates, you should document the existing support programs and the programs to be
implemented, along with the survey or other data that formed the basis for the
participation rate estimates.
Alternative Work Schedules are more commonly implemented by employers as an
employee benefit or workplace efficiency measure, rather than as a mode shift strategy.
As such, the proportion of employees that might adopt these schedules is highly
dependent on how and why the employer is implementing the program. The default
proportions using the "eligibility rate" option are currently set to 22 percent for Flexible
Work Hours, Staggered Work Hours, and 4/40 Compressed Work Weeks, and to 11
percent for 9/80 Compressed Work Weeks. These figures reflect voluntary adoption of
alternative work schedules if made available and optional. The user can change the
For an area-wide analysis, this will be the percent in the area-wide employment base; for a site-
specific (single employer) analysis, it will be the percent of employees within the firm.
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proportion of employees who would shift to each schedule to reflect local knowledge of
such programs. For example, if a given employer or set of employers decides to require
staggered hours to addressed localized congestion or compressed work weeks to reduce
overall operating costs, the proportion of employees shifting schedules could be
considerably higher.
Figure 12
Alternative Work Schedules Input Screen
ALTERNATIVE WORK SCHEDULES
Use
Default
Data
Alternative Work Schedule Parameters
Telecommute: Avg. Days/Week
Flex Time/Staggered Hours: Percent of trips
shifted from peak period
Participation Entry Format (check one only):
BSpecify Eligibility for Participation
Specify Before/After Participation Rates
1.5
A. Eligibility for Participation
Program
Flex Time
Compressed 4/40
Compressed 9/80
Staggered Hours
Telecommute
Not Eligible
Total
% Eligible
Existing
1 00%
1 00%
New
100%
100%
B. Participation Rates
Program
Flex Time
Compressed 4/40
Compressed 9/80
Staggered Hours
Telecommute
Not Participating
Total
% Participating
Existing
1 00%
1 00%
New
100%
100%
"Alternative Work Schedules" include the option to allow employees to utilize flex time, compressed work weeks, staggered work hours, or
telecommuting. Flex time and staggered hours will have the effect of shifting some trips outside of the peak period, while compressed
work weeks and telecommuting will have the effect of eliminating some work trips. Two program entry options are available:
(1) The user can specify the percentage of employees eligible for each program. Both existing and new levels of eligibility should be
specified.
(2) The user can specify existing and expected participation rates for each program.
To accomodate instances where employees are eligible for, or participate in multiple programs, the model allows the user to enter rates
that exceed 100% when summed across all alternative programs. The model then internally normalizes the rates before using them in
the travel calculations. Section 4.5 of the COMMUTER Model User Manual presents an example for this situtation.
IMPORTANT: Entry option (2) is preferred if the user can obtain data indicating a likely participation rate as a result of proposed
programs. If participation rates are specified, the employer/analyst should document existing support programs and programs to be
implemented, along with survey or other data indicating the basis for the participation rate estimates. If the user does not have survey
data indicating likely participation rates or another strong basis for estimating expected local participation rates, entry option (1) should be
used.
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Definition of Alternative Work Schedule Strategies
Flex-Time - In this policy, employees can adjust their work schedule (based on when they
arrive at and depart from the work site) in order to travel during the off-peak hours, when
there should be less traffic congestion. COMMUTER assumes a formal Flex-Time
policy rather than flexible work schedules. Flexible work schedules are seen as simply
allowing employees who would carpool or take transit to arrive or leave with slight
variations in order to be compatible with the pool/bus schedule. In contrast, a Flex-Time
policy involves formally moving the time of arrival or departure to a set of consistent
work hours that are different from the employer's official hours. This type of policy may
actually detract from employees' incentive to carpool or take transit as a means of
avoiding traffic congestion. The only assumed effect of this strategy is to shift the time
of the trips, no vehicle trips are eliminated.
Staggered Work Hours - Under this strategy, employers establish different starting times
for groups of employees in order to avoid having the entire workforce arrive or leave at
the same time. Some work sites have a large number of employees arriving within a very
narrow time period, so staggering starting hours can help reduce localized traffic
problems. This strategy is also assumed to affect only the timing of the trips, not the
number of vehicle trips.
Compressed Work Week - Under this strategy, employees are allowed to reduce the
number of work trips made by working longer hours on fewer days per week. Options
include the 4/40 schedule where 40 hours are worked in 4 days with the fifth day off and
the 9/80 schedule where 80 hours are worked in 9 days with the tenth day off.
COMMUTER assumes that the 4/40 schedule eliminates one round-trip a week (1/5 of a
daily trip) and that the 9/80 schedule eliminates one round-trip every two weeks (1/10 of
a daily trip) for each participating employee.
Telecommuting - This strategy involves allowing employees to work off-site, usually at
home via telecommunications linkups, one or more days per week. Telecommuting thus
reduces the demand for travel to the workplace. This is accounted for in COMMUTER
by simply removing person trips, along with the equivalent number of vehicle trips, from
the total amount of travel. (A more sophisticated analysis would consider how some of
the commute trips might be replaced by non-work travel.)
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5. EMISSIONS-RELATED INPUT SCREENS
In the final two input screens, you will supply the information that COMMUTER needs
to calculate emission reductions. (If you are only interested in using COMMUTER to
compute travel impacts, you don't need to enter any input information these two screens.)
To make this easier, a large matrix of MOBILE6.2 emission factors was generated for a
series of local conditions and provided with the program. (A total of 192 different sets of
emission factors are provided with COMMUTER.) To use these factors, all that you need
to do is supply a simple set of vehicle fleet characteristics, and COMMUTER will then
look up the appropriate set of MOBILE6.2 factors and use them to calculate emission
reductions from the TCM programs being evaluated. Thus, you do not have to supply
detailed, locally generated MOBILE6.2 emission factors.
If you are an experienced MOBILE6.2 user, however, and want to use emission factors
that exactly match your local conditions, you can optionally direct COMMUTER to
import and apply your locally generated factors. (Refer to Section 2.7 for step-by-step
details on generating and properly importing your own MOBILE6.2 emission factors into
COMMUTER.)
5.1 Fleet Emissions Information
In the first emissions-related input screen, you will provide the data needed for the
program to select the appropriate set of pre-loaded MOBILE6.2 emission factors or
activate the User-Supplied Emission Factors" option if you want to use your own locally
generated MOBILE6.2 factors.
Figure 13 shows the layout of this screen. If you want to use the pre-loaded emission
factors contained in COMMUTER, follow the input requirements under "Using Pre-
Loaded Factors." To use your own factors, see "Using Locally Generated Factors."
Using Pre-Loaded Factors - To use pre-loaded factors, you must select from the available
fleet characteristic options in the MOBILE Scenario section at the top of the screen that
best match your local conditions. Once you've specified all of the fleet characteristics or
changed any of these characteristics, you will be reminded to import the scenario-specific
emission factors using the "Import Default Emission Factors" command on the "File"
menu. You do not need to re-import the default emission factors if you only change the
calendar year of analysis, as each default emission factor file contains factors for all six
calendar years available. (Leave the "User-Supplied Emission Factors" and "Calendar
Year of User EFs" cells toward the bottom of the screen blank.)
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Figure 13a
Fleet Emissions Information Input Screen (p. 1)
FLEET EMISSIONS INFORMATION
Field Data Notes
MOBILE Scenario Inputs
Enter either 2007, 2009, 2010, 2013, 2019, or 2021
Calendar Year of Analysis
Season
Climate Type
I/M Program Type
Fuel Type
PADD
S = Summer, W = Winter
1 = Mild, 2 = Moderate, 3 = Severe
0 (zero) = none, 1 = Basic I/M, 2 = Enhanced I/M, 3 = OBD Only
C = Conventional, R = RFC
1, 2, 3, 4, or 5 (based on state - see below)
The "MOBILE Scenario" inputs are used by the program to select a specific set of MOBILES.2 emission factors from a series of
stored tables that best represent local conditions and emission control programs being modeled. These inputs are familiar to
MOBILES.2 users. Further clarification of these inputs for users less familiar with the MOBILES.2 emission factor model is
provided below Once the user has entered all scenario Inputs, or changed an Input, he or she must Import the scenario
emission factors using the "Import Default Emission Factors" command from the File menu.
Calendar Year - Because new vehicle emission levels continue to decrease with the introduction of each model year, current and
future vehicle fleet emissions will depend on the calendar year being analyzed.
Season - This input affects the temperature range for which emissions are modeled (emissions characteristics of vehicles vary
depending upon the temperature range in which the vehicle is being operated.) The choice of season may depend upon which
pollutants are of greatest interest. Since ozone is typically a summer problem and carbon monoxide (CO) is typically a winter
problem, summer should generally be used if ozone is of primary interest, while winter should be used if reducing CO is of
primary interest. The seasonal importance of other pollutants may vary regionally.
Climate Type - This input is used on conjunction with the "season" input to determine default temperature ranges for the model.
Choose the climate type (1 = mild, 2 = moderate, 3 = severe) that most closely matches the average daily minimum and
maximum temperatures in your area (in deg F) as specified below:
Summer-Mild: min 55/max 75
Summer - Moderate: min 65/max 85
Summer - Severe: min 75/max 95
Winter - Mild: min 52/max 72
Winter - Moderate: min 32/max 52
Winter - Severe: mini 2/max 32
If the user is interested, monthly normal temperatures for 250 cities can be looked up through the National Climatic Data Center,
http://www.ncdc.noaa.aov/oa/ncdc.html.
I/M Program Type - The type of Inspection and Maintenance (I/M) program, if any, being operated. Basic I/M refers to a program
where a simple "no-load" idle or 2500 RPM test is performed. Enhanced I/M represents programs in which a loaded IM240 or
ASM test are run on a dynamometer. OBD Only represents programs in which vehicles are not subject to an annual or biennial
inspection, but instead emissions malfunctions are identified by a vehicle's on-board diagnostics (OBD) system.
si Type - Under the 1990 amendments to the Clean Air Act, certain areas of the country must use reformulated gasoline (RFG)
beginning in 1995. This input allows the user to specify whether RFG is being used. A map and list of counties in which RFG is
required is provided on the EPA's web site, http://www.epa.gov/OMSWWW/rfg/wherevoulive.htm.
PADD - (Petroleum Administration for Defense District) - PADD's were delineated during World War II to facilitate oil allocation.
The characteristics of refined fuels, and therefore the emissions characteristics of vehicles, vary generally by PADD. The most
significant effect is on emissions of air toxics. Select the appropriate PADD (1 - 5) based on your analysis state:
1 - East Coast: Connecticut, Delaware, District of Columbia, Florida, Georgia, Maine, Maryland, Massachusetts, New
Hampshire, New Jersey, New York, North Carolina, Pennsylvania, Rhode Island, South Carolina, Vermont, Virginia, West
Virginia.
2 - Midwest: Illinois, Indiana, Iowa, Kansas, Kentucky, Michigan, Minnesota, Missouri, Nebraska, North Dakota, South Dakota,
Ohio, Oklahoma, Tennessee, Wisconsin.
3 - Gulf Coast: Alabama, Arkansas, Louisiana, Mississippi, New Mexico, Texas.
4-Rocky Mountain: Colorado, Idaho, Montana, Utah, Wyoming.
5 - West Coast: Alaska, Arizona, California, Hawaii, Nevada, Oregon, Washington.
For a map of PADDs, see: http://www.eia.doe.gov/pub/oil_gas/petroleum/analysis_publications/oil_market_basics/paddmap.htm.
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Figure 13b
Fleet Emissions Information Input Screen (p. 2)
User-Supplied MOBILE Emission Factors
^^ Mark the box to the left (with an "X") to compute emission reductions
User-Supplied Emission Factors | | using alternate MOBILES.2 emissions factors instead of the
pre-loaded factors already contained in the COMMUTER model
[Calendar Year of User EFs | | Select the calendar year of the user-supplied emission factors
The COMMUTER model has been designed to use pre-loaded MOBILES.2 emission factors for a defined range of input
conditions or a set of user-supplied emission factors for specific local conditions. Before user-supplied emission factors can be
used, the user must load these factors into the model using a two-step process:
1) MOBILES.2 database format output must be processed, using the "Process MOBILE Output" command from the File menu.
This routine requests the user to select a MOBILES.2 output file (TB1), and then produces a text file with the extension "TBZ,"
that is formatted for import into the COMMUTER Model.
2) The TBZ data file must be imported, using the "Import User Emission Factors" command from the File menu. The user can
choose a different TBZ file without having to process MOBILE output every time.
The "Process MOBILE Output" command requires the availability of a MOBILES.2 output file in database format (TB1 file
extension), along with corresponding toxics (TOX) and particulate (.PM) output files that have the same base file name as the
TB1 file. The resulting TBZ file can be stored with the COM M UTER Model for future use, and the TB1, TOX, and . PM files
deleted or moved if desired. The database output options must be specified as shown in the sample MOBILES.2 input file
provided and described in Section 5 of the User Manual. The "Calendar Year of User EFs" input identifies the specific calendar
year factors from the set of user-supplied factors. The calendar year can be any year between 1960 and 2050, but must match
one of the available calendar years in the user-provided MOBILES.2 output files. (These output files may include a maximum of
six calendar year scenarios.)
Each of these "pre-loaded" fleet characteristics inputs is explained below.
Calendar Year - Since vehicle fleet emission levels change as new technology
improvements are introduced on newer cars, the calendar year that represents the
analysis scenario must be entered.
You can choose either 2007, 2009, 2010, 2013, 2019, or 2021. If you are
interested in an analysis year between two of those years, the model should be
run for both of the surrounding years (for example, if you are interested in 2008,
you should run analyses for both 2007 and 2009). You will then need to
interpolate the resulting travel and emission impacts to represent impacts in the
year of interest.
When you choose the year, you should keep in mind the time period when the
TCMprograms being modeled will actually be implemented. For example, in
evaluating improved levels of transit service, it may take a couple of years to
implement the service improvements.
Season - Vehicle emissions vary depending upon the ambient temperature and,
in some areas, fuel controls are imposed only in certain seasons. You therefore
need to enter the season for the analysis of interest, selecting either "S" (summer)
or "W" (winter). If you are an air quality planner, you will generally select
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summer when evaluating ozone-related emission reductions (including VOC and
NOx), and winter for carbon monoxide evaluations. The seasonal importance of
other pollutants may vary regionally.
Climate Type - This input is used in conjunction with the "season" input to
determine temperature ranges for the model. You should choose the climate type
(1 = mild, 2 = moderate, 3 = severe) that most closely matches the average daily
minimum and maximum temperatures in your area (in degrees Fahrenheit), in
either summer or winter depending upon your analysis season:
Summer - Mild (S, 1): min 55/max 75
Summer - Moderate (S, 2): min 65/max 85
Summer - Severe (S, 3): min 75/max 95
- Winter - Mild (W, 1): min 52/max 72
- Winter - Moderate (W, 2): min 32/max 52
- Winter - Severe (W, 3): min 12/max 32
You may, if you choose, look up monthly normal temperatures for your city
through the National Climatic Data Center,
http://www.ncdc.noaa.gov/oa/ncdc.html. Data for 250 cities are provided at no cost
on this web site. In most areas, summer temperatures for July and winter
temperatures for January (when temperatures are at their highest and lowest) should
be used.
I/M Program Type - The type of Inspection and Maintenance (I/M) program, if
any, being operated in your area will affect fleet emissions. If you do not know
what type of I/M program is in place in your area, your state department of
environmental protection or department of motor vehicles should be able to tell
you. The following I/M program options are available:
None (0) - No I/M program exists in your area.
Basic I/M (1) - A program where a simple "no-load" idle or 2500 RPM test is
performed along with a visual inspection;
Enhanced I/M (2) - A program in which a loaded IM240 or ASM test are run
on a chassis dynamometer in conjunction with a visual and functional
emission control system inspection;
OBD Only (3) - A program in which vehicles are not subject to an annual or
biennial inspection, but instead emissions malfunctions are identified by a
vehicle's on-board diagnostics (OBD) system.
Fuel Type - Under the 1990 amendments to the Clean Air Act, certain areas of
the country must use reformulated gasoline (RFG) beginning in 1995. This input
allows the user to specify whether RFG is being used. A map and list of counties
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in which RFG is required is provided on the EPA's web site,
http://www.epa.gov/OMSWWW/rfg/whereyoulive.htm.
PADD - (Petroleum Administration for Defense District) - PADDs were
delineated during World War II to facilitate oil allocation. The characteristics of
refined fuels, and therefore the emissions characteristics of vehicles, vary
generally by PADD. The most significant effect is on emissions of air toxics.
Select the appropriate PADD (1 - 5) based on your analysis state:
1 - East Coast: Connecticut, Delaware, District of Columbia, Florida, Georgia,
Maine, Maryland, Massachusetts, New Hampshire, New Jersey, New York,
North Carolina, Pennsylvania, Rhode Island, South Carolina, Vermont,
Virginia, West Virginia.
2 - Midwest: Illinois, Indiana, Iowa, Kansas, Kentucky, Michigan, Minnesota,
Missouri, Nebraska, North Dakota, South Dakota, Ohio, Oklahoma,
Tennessee, Wisconsin.
3- Gulf Coast: Alabama, Arkansas, Louisiana, Mississippi, New Mexico,
Texas.
4 - Rocky Mountain: Colorado, Idaho, Montana, Utah, Wyoming.
5 - West Coast: Alaska, Arizona, California, Hawaii, Nevada, Oregon,
Washington.
For a map of PADDs, see:
http://www.eia.doe.gov/pub/oil_gas/petroleum/analysis_publications/oil_market_ba
sics/paddmap.htm.
Using Locally Generated Factors - Once you have successfully imported your own
locally generated MOBILE6.2 emission factors into COMMUTER as described in
Section 2.7, you can direct COMMUTER to apply them in the emission reduction
calculations by marking the "User-Supplied Emission Factors" box (with an "X") toward
the bottom of the screen. Once you activate this option, you must then enter the specific
calendar year of the emission factors you've imported in the "Calendar Year of User EFs"
input cell. (This input is used to select a specific calendar year from a set of factors
you've imported that may encompass multiple calendar years. Even if you've only
imported emission factors for a single year, you must enter it into this input cell.)
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NOTE: When you activate the "User-Supplied Emission Factors"
option, any entries you may have made in the "MOBILE Scenario
Inputs" cells at the top of the screen are ignored. In addition, the
vehicle fleet mix and VMTmix by facility type that you've specified
in your locally generated emissions factors file is automatically
loaded into the appropriate cells in the "Other Emissions-Related
Data " screen that follows.
5.2 Other Emissions-Related Data
In this final input screen, you will provide additional emission-related inputs that
COMMUTER will then use in conjunction with the MOBILE6.2 emission factors
discussed in Section 5.1 to calculate "before TCM" (i.e., existing) and "after TCM" daily
emissions for the vehicle fleet. It will then determine the resulting emission reductions
from the TCMs being evaluated.
Figure 14 shows the Other Emissions-Related Data input screen. Each of the inputs you
will be required to enter is described below.
Vehicle Fleet VMT Mix - The light-duty vehicle fleet is composed of nine different
classes of vehicles, which are listed on the screen. The VMT mix for the vehicle fleet
refers to the percent of the total travel (VMT) that is driven by each of the nine vehicle
classes. The emission factors in MOBILE6.2 are based on vehicle class. COMMUTER
will calculate emissions for the entire vehicle fleet (referred to as the fleet composite
emissions) based on the percentage of VMT in each vehicle class, by weighing the
emission factors together according to the fleet mix input.
If known, you should supply local data on fleet mix for the analysis area in the "Local"
column. Only the light-duty vehicle mix (vehicles <8,500 Ib.) is required, since the
strategies analyzed by COMMUTER are not intended to affect travel by heavy-duty
vehicles (trucks). You may enter the vehicle mix either as a percentage of all light-duty
vehicles (in which case the total should sum to 100%), or as a percentage of all vehicles
including heavy-duty vehicles. If the total you enter is less than 100%, COMMUTER
will assume that you have selected the second alternative and will normalize the
percentages to 100%, to represent the fractions of light-duty vehicles.
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Figure 14
Other Emissions-Related Data Input Screen
OTHER EMISSIONS-RELATED DATA
Use
Default
Data
Local Default
Explanatory Notes
Vehicle Fleet VMT Mix |__
LDGV - Light-Duty Gas Vehicles
LDGT1 - Light-Duty Gas Trucks 1
LDGT2 - Light-Duty Gas Trucks 2
LDGT3 - Light-Duty Gas Trucks 3
LDGT4 - Light-Duty Gas Trucks 4
LDDV - Light-Duty Diesel Vehicles
LDDT12 - Light-Duty Diesel Trucks 1 & 2
LDDT34 - Light-Duty Diesel Trucks 3 & 4
MC - Motorcycles
TOTAL
Affected Vehicle Speed (mph) ^
Peak Period Average Speed - Freeways
Off-Peak Period Average Speed - Freeways
Peak Period Average Speed - Arterials
Off-Peak Period Average Speed - Arterials
Percent of VMT by Facility Type ^
Freeway
Arterial
Local Road
Ramp
TOTAL (must add to 100%)
Percentages of total VMT by vehicle type
Passenger Cars
0-6,000 Ibs. GVWR, 0-3,750 Ibs. LVW
0-6,000 Ibs. GVWR, 3,750-3,750 Ibs. LVW
6,000-8,500 Ibs. GVWR, 0-5,750 Ibs. ALVW
6,000-8,500 Ibs. GVWR, over 5,750 Ibs. ALVW
Passenger Cars
0-6,000 Ibs. GVWR
6,000-8,500 Ibs. GVWR
Gasoline
If not 100%, model will normalize
Average speed (mph) of TCM-affected trips
Vehicle Fleet VMT Mix
MOBILE6 generates emission factors for each of the nine different vehicle classes listed. Fleet "composite" emission factors
are then calculated by weighting these emission factors by the percentage of travel (i.e., VMT) in each vehicle class. The
default VMT mixes provided by this program are MOBILE6 national default values. These defaults are calendar year specific;
you must enter a calendar year under the Fleet Emissions Information screen before the defaults will appear. If you
are using user-supplied emission factors, the emissions factor import routine will automatically generate and look up a VMT
mix from your MOBILE6 output file. If you are using default emission factors and do not enter local data for a VMT mix, the
model will use the default MOBILE6 VMT mix.
Only the light-duty vehicle mix (vehicles <8,500 Ib.) is required, since the strategies analyzed by COMMUTER are not intended
to affect travel by heavy-duty vehicles (trucks). The user may specify the VMT mix either as a percentage of a|| vehicles, or as
a percentage of light-duty vehicles. If the total of the light-duty vehicle categories entered is less than 100%, the model will
assume that the user is entering the percentage of all vehicles (including heavy-duty) and will normalize these percentages to
total 100% (representing the fraction of light-duty vehicles).
Note: GVWR = Gross Vehicle Weight Rating; LVW = Loaded Vehicle Weight; ALVW = Adjusted Loaded Vehicle Weight.
Affected Vehicle Speed
Vehicle emissions vary with speed. The values entered here should represent regional network average speeds during the
peak and off-peak periods. Default values supplied are based upon HPMS (Highway Performance Monitoring System)
averages compiled by urban area size.
Percent of VMT by Facility Type
Vehicle emissions vary by roadway facility type because of the different traffic operating characteristics on different facilities
(e.g., freeway travel typically involves less starting and stopping than travel on other roads). MOBILE6 defines four facility
types: freeways, arterials, local roads, and freeway ramps. If user-supplied emission factors are provided, the facility mix will
be read from the user-supplied MOBILE output files and the user does not need to specify the mix. If default emissions factors
provided with the COMMUTER model are used, you may either specify a local facility mix or use the default mix that is
provided with the model.
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If local data are not available, you can check the boxes in the "Use Default" column to
use the national default fleet mixes obtained from MOBILE6.2. Note that the default
fleet mixes vary by calendar year.
As indicated in Section 5.1, if you are using your own locally generated emission factors,
the VMT mix from your MOBILE6.2 emission factor file is automatically loaded into
these input cells.
Affected Vehicle Speeds - The values you enter here should represent existing average
vehicle speeds in your region. You should be able to obtain data on average travel speeds
from transportation planning staff at the regional transportation planning agency. Even if
you are running a site-specific analysis, enter speeds that represent averages for your
urban region.
You will need these values for both peak and off-peak periods, and for freeways as well
as arterials.* Peak period travel speed should be the average of travel speeds in the AM
and PM peak periods, if these values differ.
CAUTION: Do not specify travel speeds at a geographic area
smaller than the county level. Even if you are performing a site-
specific analysis, the speed inputs should reflect average regional
network travel speeds that employees at the site experience driving
to and from work.
You may also choose to use default travel speeds, shown in Table 2, if local data from the
regional MPO are not available. These default values have been estimated from national
highway data. Travel speeds will vary depending on metropolitan area size, since larger
areas tend to be more congested.
In most cases, the MPO for a given region is responsible for both transportation planning and emissions
analysis. The MPO maintains local data related to travel demand, speed, and emissions inventories for
regional planning purposes. These data are typically available to member agencies (counties, cities, transit
operators) and businesses. Metropolitan-level emissions inventory data sets generally provide local data on
travel speeds by peak and off-peak periods that are generated from the travel demand modeling process and
used in regional air quality conformity analysis.
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Table 2
Default Speeds (mph) by Area Size
Period
Peak
Off-Peak
Highway
Type
Freeway
Arterial
Freeway
Arterial
Large
40.2
22.6
49.0
25.1
Urban Area Size
Medium
46.8
23.2
54.7
25.5
Small
50.5
24.2
56.4
26.0
VMT by Facility Type
Vehicle emissions vary by roadway facility type because of the different traffic operating
characteristics on different facilities (e.g., freeway travel typically involves less starting
and stopping than travel on other roads). MOBILE6 defines four facility types: freeways,
arterials, local roads, and freeway ramps. If user-supplied emission factors are provided,
the facility mix will be read from the user-supplied MOBILE output files and you do not
need to specify the mix. If the default emissions factors provided with the COMMUTER
model are used, you may either specify a local facility mix or use the default mix that is
provided with the model.
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6. REFERENCES
J. R. Kuzmyak, et. al., "Procedures Manual for Estimating Emission Reductions
from Voluntary Measure and Commuter Choice Incentive Programs", prepared for
the U.S. Environmental Protection Agency," Draft Final Report, September 19,
1999.
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