Commuter Programs:
Quantifying and Using Their
Emission Benefits in SIPs and
Conformity
Guidance for State and Local Air and
Transportation Agencies
&EPA
United States
Environmental Protection
Agency
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Commuter Programs:
Quantifying and Using Their
Emission Benefits in SIPs and
Conformity
Guidance for State and Local Air and
Transportation Agencies
Transportation and Climate Division
Office of Transportation and Air Quality
U.S. Environmental Protection Agency
NOTICE
This technical report does not necessarily represent final EPA decisions or
positions. It is intended to present technical analysis of issues using data
that are currently available. The purpose in the release of such reports is to
facilitate the exchange of technical information and to inform the public of
technical developments.
United States
Environmental Protection
Agency
EPA-420-B-14-004, February 2014
Supersedes EPA-420-B-07-015
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Contents
Section 1: Background Information 4
1.1 What is the purpose of this guidance? 4
1.2 What are commuter programs, and how do they work? 5
1.3 Does this guidance create any new requirements? 6
1.4 Who should I contact if I have questions on this guidance? 6
Section 2: Basic Requirements for Using Emissions Reductions from Commuter
Programs 7
2.1 What are the basic requirements for using emission reductions in SIPs? 7
2.2 What must a state submit to EPA to meet the requirements for incorporating a
commuter program as a control measure in a SIP? 8
2.3 How can the estimated emission reductions be used for SIP purposes? 9
2.4 How can the emission reductions be used for transportation conformity
purposes? 9
2.5 What quantification methodologies are available to estimate emission reductions
of commuter programs for SIPs and transportation conformity
determinations? 11
2.6 What types of penalties can be assessed for not complying with CAA
requirements? 13
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Section 1: Background Information
1.1 What is the purpose of this guidance?
The purpose of this guidance is to help states or agencies1 estimate the emission benefits
of commuter programs and, under appropriate circumstances, take credit for them in SIPs
and conformity determinations. "Commuter programs" are programs that provide
incentives or support to employees to reduce the frequency that they drive alone to work,
and are offered by private- and public-sector employers throughout the country. Through
these commuter programs, the numbers of vehicle trips and miles, and hence, emissions
of criteria pollutants, as well as greenhouse gases, are reduced in many communities.
This has led to an interest on the part of planners in some areas to incorporate the criteria
pollutant benefits into their state implementation plans (SIPs) or transportation
conformity determinations.
Commuter programs can be incorporated into the SIP as mandatory measures, an
Economic Incentive Program (EIP) or as a voluntary mobile source measure. For each
of these options, a different entity may administer and evaluate the commuter program's
measures. For example, a voluntary measure program may be entirely administered by
individual employers. EPA has issued comprehensive guidance documents for each of
these types of SIP measures, and you should consult the guidance for the type of SIP
submission in which you are interested as this guidance does not reiterate all the
requirements for each.
Quantifying the emissions benefits from commuter programs is covered in Section 2,
which has information regarding the basic submission and quantification requirements for
commuter programs in SIPs and conformity.
This guidance supersedes the 2007 document, "Guidance for Quantifying and Using
Emission Reductions from Best Workplaces for Commuter Programs in State
Implementation Plans and Transportation Conformity" (EPA420-B-07-015). In addition,
with the release of EPA's MOtor Vehicle Emissions Simulator (MOVES) model, the
COMMUTER model described in the 2007 guidance can no longer be used, as it was
based on MOBILE, the model that preceded MOVES. The 2007 guidance and the
COMMUTER model have been removed from EPA's website.
This document uses "state or agency" to refer to those entities that have authority to submit a SIP or
conformity determination, such as a local or state government, regional transit authority, local or regional
transportation planning agency or state or regional air quality agency.
EPA's Economic Incentive Program guidance and Mobile Source Voluntary Measures Policy can be
found on EPA's web site at: http://www.epa.gov/otaq/stateresources/policv/pag guidance.htm and also at:
http://www.epa.gov/ttn/ecas/incentiv.html.
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1.2 What are commuter programs, and how do they work?
Commuter programs are those programs that reduce the frequency that employees drive
alone to work. These programs are usually offered to employees by their employer, but
other organizations, such as a business park,
downtown district, developer, or property
owner may provide them. These programs
can consist of any of the following
components:
Commuter Choice program means an
organized program to encourage employers to
offer flexible commuter benefit options to
employees.
cn/i
Best Workplaces for Commuters is a
innovative membership program that provides
qualified employers with national recognition for
offering outstanding commuter benefits. BWC
assists participating employers by offering public
recognition and promotion, technical assistance,
training, web-based tools, and forums for
information exchange.
Commuter benefit options are any of a number
of flexible commute benefits offered by
employers. Basic Commuter Choice alternatives
include transit benefits, vanpool benefits, cash,
or parking.
• Free or reduced cost fares for public
transportation (such as subway cards,
bus tokens, or train tickets),
• Transit and vanpool vouchers and
subsidies,
• Services to facilitate vanpools and
carpools (such as providing vans, ride-
matching, and guaranteed ride home
services),
• Park and Ride subsidies,
• Telecommuting options (so employees
can work at home more often),
• Proximate Commuting: a program that matches employees of multi-site
employers (such as banks or chain stores) to the branch office nearest their home,
• Incentives to bike and walk, and
• Parking Cash Out: employees can trade employer-paid parking space for cash or
other benefits.
With more options, commuters can be expected to use single-occupant vehicles less
often. Reducing the frequency that commuters drive alone generates air quality benefits.
Air quality improvements are due to the reduction of emissions associated with a
reduction in vehicle miles traveled. The Clean Air Act acknowledges these types of
programs at Section 108(f), which includes a list of categories of "transportation control
measures." Several of the categories on the Section 108(f) list could describe commuter
programs, or the components of one, such as,
• "(iii) employer-based transportation management plans, including incentives;"
• "(viii) programs for the provision of all forms of high-occupancy, shared-ride
services;" and
• "(x) programs for secure bicycle storage facilities and other facilities.
among others.
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1.3 Does this guidance create any new requirements?
This guidance does not create any new requirements, but explains to state and local air
agencies, transportation agencies, MPOs, and the general public how the air quality
benefits of commuter programs could be included in a SIP or in a transportation
conformity determination. The Clean Air Act (CAA) and implementing regulations
contain legally binding requirements. SIP requirements can be found in Clean Air Act
sections 110(a)(2) and 172(c). Transportation conformity requirements can be found in
Clean Air Act section 176(c) and applicable regulations (40 CFR Parts 51 and 93). This
guidance document does not substitute for those provisions or regulations, nor is it a
regulation itself. Thus, it does not impose binding, enforceable requirements on any
party, and may not be applicable in all situations. EPA and State decision makers retain
the discretion to adopt approaches for approval of SIP measures that differ from this
guidance where appropriate and consistent with applicable law and regulations. Any
final decisions by EPA regarding a particular SIP measure will only be made based on
the statute and regulations in the context of EPA notice and comment rulemaking on a
submitted SIP revision. This guidance may be revised periodically without public notice.
1.4 Who should I contact if I have questions on this guidance?
If you are interested in including the emission benefits of a commuter program into a SIP
or transportation conformity determination, please contact the EPA Regional Office with
responsibility for air quality planning in the relevant area. A contact list of EPA Regional
Offices is available at the following web address:
http://www.epa.gov/otaq/transp/conform/contacts.htm
For general questions regarding this document, please contact Laura Berry at (734) 214-
4858 or berry.laura@epa.gov.
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Section 2: Basic Requirements for Using Emissions Reductions
from Commuter Programs
2.1 What are the basic requirements for using emission reductions in
SIPs?
In order to be approved as a measure which provides additional emission reductions in a
SIP, a control measure - in this case, a commuter program - cannot interfere with other
requirements of the CAA, and would need to be consistent with SIP reasonable further
progress, attainment, or maintenance requirements, as applicable. In addition, the control
measure must provide emission reductions that meet the requirements described below.
(A) Quantifiable - The emission reductions from a control measure are quantifiable if
they can be reliably measured or modeled, and the quantification can be replicated.
Emission reductions must be calculated for the time period for which the reductions will
be used in the SIP. See Section 2.5 for more information on quantifying emission
reductions from commuter programs.
(B) Surplus - Emission reductions are generally surplus if they are not otherwise relied
on to meet other applicable air quality attainment and maintenance requirements (i.e., no
double-counting of emission reductions). In the event that the measure is used to meet
such air quality-related program requirements, the measure is no longer surplus and may
not be used for additional credit.
(C) Federally Enforceable - Depending on how the emission reductions are to be used,
control measures must be enforceable through a SIP. Where the emission reductions are
part of a rule or regulation for SIP purposes, they are considered federally enforceable if
they meet all of the following requirements:
• They are independently verifiable.
• Violations are defined, as appropriate.
• The state or agency and EPA have the ability to enforce the measure if
violations occur.
• Those liable for violations can be identified.
• Citizens have access to all the emissions-related information obtained
from the responsible party.
• Citizens can file suits against the responsible party for violations.
• Violations are practicably enforceable in accordance with EPA guidance
on practicable enforceability.
• A complete schedule to implement and enforce the measure has been
adopted by the implementing agency or agencies.
Because commuter programs may rely on voluntary actions of individuals and other
parties, these programs may be considered under EPA's "Guidance on Incorporating
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Voluntary Mobile Source Emission Reduction Programs in State Implementation Plans
(SIPs)" (the VMEP guidance).3 The purpose of the VMEP guidance is to support
innovative methods in achieving emission reductions for SIPs. If a SIP revision that
relies on the VMEP guidance is approved, the state is responsible for assuring that the
reductions credited in the SIP occur. The state would need to make an enforceable SIP
commitment to monitor, assess and report on the emission reductions resulting from the
voluntary measure and to remedy any shortfalls from forecasted emission reductions in a
timely manner.
Under the VMEP guidance, the amount of emission reductions allowed for voluntary
mobile source measures, including commuter programs, in a SIP is not expected to
exceed three percent of the total reductions needed to meet any requirements for
reasonable further progress, attainment or maintenance, as applicable. 4
(D) Permanent - The emission reduction must be permanent throughout the time period
that the reduction is used in the applicable SIP.
(E) Adequately Supported - The state must demonstrate that it has adequate funding,
personnel, and other resources to implement the control measure on schedule.
2.2 What must a state submit to EPA to meet the requirements for
incorporating a commuter program as a control measure in a
SIP?
The state must submit to EPA a document which:
• Identifies and describes the commuter program and its implementation schedule
to reduce emissions within a specific time period;
• Contains estimates of emission reductions attributable to the commuter program,
including the methodology and all other relevant technical support documentation
for your estimates (you must rely on the most recent information available at the
time the SIP is developed);
• Either contains federally enforceable requirements for the state to implement,
track, and monitor the commuter program; or if the measure is developed under
the VMEP guidance, the state includes an enforceable commitment to monitor,
assess and report the resulting emission reductions of the commuter program;
3 This guidance is found at: www.epa.gov/otaq/stateresources/policv/pag guidance.htm.
4 EPA acknowledges that it may be possible to demonstrate that voluntary measures may achieve credible
reductions higher than the three percent cap. In that case, EPA will re-evaluate that cap on a case-by-case
basis and allow the cap to be exceeded if the cap hinders the implementation of effective voluntary control
measures, subject to notice and comment during SIP approval. Interested parties should refer to the VMEP
guidance for more information when a specific commuter program is under development.
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• If the measure is developed under the VMEP guidance, includes an enforceable
commitment to remedy any SIP emissions shortfall in a timely manner in the
event that the commuter program does not achieve the estimated emission
reductions; and
• Meets all other requirements for SIP revisions under sections 110 and 172 of the
CAA.
2.3 How can the estimated emission reductions be used for SIP
purposes?
For a reasonable further progress, attainment or maintenance SIP, you can use the
emission reductions produced from the commuter program by applying the following
criteria:
(A) Where required, emission reductions must account for seasonality. For
example, if your SIP credits only those reductions which take place during the
summer ozone season, then only reductions which take place during that season
may be credited.
(B) An appropriate baseline must be chosen, so that the reductions are estimated
only from measures that are not already accounted for in the baseline estimates.
For example, if commuter programs were already in effect when the SIP was
developed and were accounted for in the SIP's baseline, the emission reductions
associated with implementation or continuation of those same programs cannot be
included as surplus emission reductions for the SIP.
(C) As required by Clean Air Act section 172(c)(3) and EPA's regulation at 40
CFR 51.112(a), states must use the latest planning assumptions available at the
time that the SIP is developed. In addition, the latest emissions model approved
by EPA must be used in quantifying reductions from SIP control measures that
are under development. State, local, and other interested agencies should consult
with their EPA Regional Office on the latest approved MOVES model for use in
quantifying motor vehicle emissions in most states and the latest approved
EMission FACtor (EMFAC) model for use in California.
2.4 How can the emission reductions be used for transportation
conformity purposes?
The transportation conformity regulation (40 CFR Part 93) describes the requirements for
including emission reductions from on-road mobile control measures in a conformity
determination for a transportation plan, transportation improvement program (TIP), or
transportation project. The conformity rule requires a regional emissions analysis be
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conducted for the transportation plan and TIP. In the regional emissions analysis, the
emissions from the planned transportation system are estimated or modeled, just as they
are when creating or revising a SIP's motor vehicle emissions budget. If credit is
obtained for a commuter program in the SIP's motor vehicle emissions budget,
transportation agencies should also include the credit in the regional emissions analysis of
the transportation conformity determination to the extent the program is being or will be
implemented and appropriate commitments have been made, as described below.
To include emission reductions from a commuter program in a regional emissions
analysis, the appropriate jurisdictions must be committed to implementing the measure.
The appropriate level of commitment varies according to the requirements outlined in 40
CFR 93.122(a), which are described as follows:
(A) If the measure does not require a regulatory action to be implemented, it can
be included in an emissions analysis if it is included in the transportation plan and
TIP with sufficient funding and other resources for its full implementation.
(B) If the measure requires a regulatory action to be implemented, it can be
included in an emissions analysis if one of the following has occurred:
(1) The regulatory action for the measure is already adopted by the
enforcing jurisdiction (e.g., a state has adopted a rule to require a control
measure);
(2) The measure has been included in an approved SIP; or
(3) There is a written commitment to implement the measure in a
submitted SIP with a motor vehicle emissions budget that EPA has found
adequate.
(C) If an on-road mobile measure is not included in the transportation plan and
TIP or the SIP, and it does not require a regulatory action to be implemented, then
it can be included in the regional emissions analysis if the conformity
determination contains a written commitment from the appropriate entities to
implement the measures. Section 93.101 of the conformity rule defines what is
intended by a "written commitment."
Whatever the case, the emission reductions from a commuter program can only be
applied in a conformity determination for the time period or years in which the measure
will be implemented and in effect. Written commitments must come from the agency
with the authority to implement the measure. The latest emissions model and planning
assumptions that are available must be used when calculating emission reductions from
the measure, according to 40 CFR 93.110 and 93.111.
Areas should utilize the conformity interagency consultation process to discuss the
methods and assumptions used to quantify the reductions from the measure. The
conformity determination should include documentation of the methodology,
assumptions, and models that were used to calculate emission reductions from the
commuter program as well any commitments that are necessary for implementation, as
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described above.
2.5 What quantification methodologies are available to estimate
emission reductions of commuter programs for SIPs and
transportation conformity determinations?
If a commuter program is considered to be regionally significant, then the travel impacts
of the program should be considered in the context of a nonattainment or maintenance
area's regional travel demand forecasting.5 (See 40 CFR 93.122 for applicable
procedures for determining regional transportation-related emissions.) The interagency
consultation process should be used to determined which projects are considered
regionally significant (see 40 CFR 93.105(c)(l)(ii)). An example of the regionally
significant project may be a campaign to implement commuter programs for all
employers of a certain size or number of employees throughout a metropolitan area.
However, EPA expects that the majority of commuter programs would not be regionally
significant, and therefore the emission reductions could be quantified using modeling
techniques other than regional travel models (i.e., "off-model" techniques or
methodologies). State, local, and federal air quality and transportation agencies should
consult on what methods and data are appropriate for quantifying the impacts of
commuter programs for SIPs and conformity determinations.
To estimate the emission reductions due to commuter programs, the recommended
approach is to estimate the number of commuters who would change their mode of travel
(i.e., single-occupant vehicle (SOV), carpool, vanpool, transit, bicycle, etc.) or trip-
making behavior (e.g., telecommuters will no longer be making regular worktrips) in
response to incentives, assistance, or support offered through a commuter program. From
this, the resultant change in vehicle activity could be calculated. The next step would be
to use this information with the latest emissions model approved by EPA (i.e., the latest
version of MOVES or EMFAC in California) to estimate the emissions that the
commuter program would reduce.6
Forecasting travel behavior impacts is typically the most challenging aspect of
quantifying a commuter program. Commuter programs can have a wide range of
effectiveness, based on the details of the particular programs and their implementation
context. The following paragraphs describe currently available tools for quantifying the
5Section 93.101 of the transportation conformity rule defines a "regionally significant project" as applying
to a project that is on a facility that 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.
6 The latest version of EPA's Motor Vehicle Emission Simulator (MOVES) model, as well as model
guidance, the user guide, and other documentation can be found on EPA's website at:
http://www.epa.gov/otaq/models/moves/index.htm. The latest version of California's EMFAC model and
model documentation can be found on the California Air Resources Board website at:
http ://www. arb .ca. gov/msei/modeling. htm.
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travel impacts of non-regionally significant commuter programs.
Available Tools for Non-regionally Significant Measures
For commuter programs that are not regionally significant, EPA may accept the use of
other methodologies and analytic tools, in combination with the latest emissions model
approved by EPA, to estimate the emission reductions of commuter programs for SIPs
and conformity purposes. As mentioned above, EPA expects that the majority of
commuter programs would not be regionally significant.
For example, the Center for Urban Transportation Research TREVIMS (Trip Reduction
Impacts of Mobility Management Strategies) is one such tool that can estimate the
change in vehicle activity from a commuter program, and others are also available.
Considerations for Data for Quantification of All Commuter Programs
When quantifying the impacts of commuter programs, a state or agency should
carefully consider the underlying data utilized to estimate travel behavior, especially if
using off-model and sketch planning techniques. The interagency consultation process
should be used when deciding the appropriate inputs and methods for quantifying the
emissions reductions associated with commuter programs. The following items should
be considered when quantifying the travel impacts of any commuter program.
(A)Reasonable assumptions for employee participation. A state or agency should
assume a reasonable level of participation from eligible employees, since not every
eligible employee may be expected to take advantage of a commuter program.
Survey methods can be used to capture the level of employee participation, both
before and after a measure has been implemented. For example, a survey of
employees at an employment site may be performed to determine how many people
expect to use or have actually used employer-subsidized transit passes. Pre- and post-
implementation surveys of actual travel behavior are often both feasible and
necessary if the effectiveness of a commuter program is to be evaluated
retrospectively.
(B) Experience from other areas. In some cases, a state or agency may be able to use
input information from other nonattainment or maintenance areas when an area does
not have such local information. For example, a study may have found in another
area that five percent of office workers will telecommute one day a week if provided
the opportunity. It is important to consider whether information from another area is
appropriate to apply to your area.
(C) Elasticities. Finally, a state or agency should use the most appropriate elasticity
assumptions for travel decisions when quantifying commuter programs. An elasticity
says that an X percent change of an input variable (e.g., the cost of parking) produces
a Y percent change of an output variable (e.g., drive-alone mode share). Elasticities
may be developed from direct observation or from coefficients of a model such as a
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mode choice model. While such elasticities can account for different levels of the
input variable, they are not necessarily valid outside the range for which they were
developed. For example, an increase in the cost of parking from $0.00 to $1.00 is an
infinite percentage change, producing meaningless results. Also, elasticities
developed in one setting cannot necessarily be assumed accurate in another setting.
For example, the elasticity describing how driving alone varies with the percentage
change in the cost of parking developed from a dense urban area with extensive
transit alternatives would be different from that same elasticity developed in a
suburban area with limited transit.
Another important consideration is interaction among strategies. Some strategies may
complement each other (e.g., parking management and ridesharing incentives), leading to
cumulative effects greater than the sum of the effects of the strategies if applied
individually. Conversely, in some cases the effects of multiple programs may be smaller
than the sum of their individual effects.
2.6 What types of penalties can be assessed for not complying with
CAA requirements?
Use of this guidance does not relieve you of any obligation to comply with all otherwise
applicable CAA requirements, including those pertaining to the crediting of emission
reductions for your SIP, such as for your attainment demonstration or maintenance plan.
Violations of CAA requirements are subject to administrative, civil, and/or criminal
enforcement under Section 113 of the CAA, as well as to citizen suits under Section 304
of the CAA. The full range of penalty and injunctive relief options would be available to
the federal or state government (or citizens) bringing the enforcement action.
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