Guidance for Implementing the Clean Air 

Act Section 176(c)(8) Transportation 

Control Measure Substitution and Addition 

Provision 
Guidance for Implementing the Clean Air 


Act Section 176(c)(8) Transportation 


Control Measure Substitution and Addition 


Provision


Transportation and Regional Programs Division 

Office of Transportation and Air Quality 

U.S. Environmental Protection Agency 

EPA-420-B-09-002 

January 2009 
TABLE OF CONTENTS 

Page 

Section 1: Introduction.................................................................................................................1 

1.1 What is the purpose of this guidance? 

1.2 What TCMs are addressed by Clean Air Act section 176(c)(8) and this guidance document? 

1.3 What are the transportation conformity rule’s requirements for timely implementation of 

TCMs? 

1.4 Is a conformity determination or a SIP revision required when a substitution is made or 

when a TCM is added to the SIP? 

1.5 Does this guidance create new requirements? 

1.6 Who can I contact for more information? 

1.7 Where can I find more information on the web? 

Section 2: Substituting Transportation Control Measures in an Approved SIP....................5 

2.1 When can states use the TCM substitution provision in the Clean Air Act? 

2.2 What does the Clean Air Act require in order for a TCM substitution to occur? 

2.3 What additional information should be provided to support a TCM substitution? 

2.4 How does a state air agency, MPO or other transportation agency demonstrate that a 

substitute TCM provides equivalent emissions reductions? 

2.5 If the SIP does not include any emissions reductions from a TCM, can it be substituted with 

another TCM without an analysis? 

2.6 Can the TCM substitution process be used to remove a TCM from the applicable SIP 

without providing a substitute measure? 

2.7 If a substitute TCM cannot be implemented on the same schedule as the original TCM, what 

is necessary in order to fulfill the Clean Air Act requirement that “the replacement TCM 

must be implemented as soon as practicable but not later than the date on which emissions 

reductions are necessary to achieve the purpose of the implementation plan?” 

2.8 Can the substitution process be used if the substitute TCM could not be implemented until 

after the date on which emissions reductions are necessary to achieve the purpose of the 

implementation plan? 

2.9 How would the TCM substitution process work in an area that is nonattainment and/or 

maintenance for two or more pollutants, where the original TCM is included in the SIP for 

only one pollutant? 

2.10 Can the TCM substitution process be used to replace a TCM in an approved SIP for an air 

quality standard that has been revoked if the area remains nonattainment and/or 

maintenance for other pollutants? 

2.11 When can an MPO make a conformity determination based on a substitution? 

2.12 What must a state air agency do if a substitute TCM provides greater emissions reductions 

than the original TCM and the agency wants to incorporate the additional reductions into its 

control strategy SIP or maintenance plan? 

i 
Section 3: Adding Transportation Control Measures to an Approved SIP..........................13 

3.1 What is required in order for a new TCM to be added to an area’s approved SIP through the 

process established in Clean Air Act section 176(c)(8)? 

3.2 What additional information should be provided to support the addition of a TCM to an 

approved SIP? 

3.3 Can all nonattainment and maintenance areas add TCMs to their approved SIPs? 

3.4 What must a state air agency do if it wants to incorporate the emissions reductions from an 

additional TCM into its control strategy SIP or maintenance plan? 

Section 4: Process Requirements That Apply When Substituting or Adding 

Transportation Control Measures to an Approved SIP.......................................15 

4.1 What is necessary for an MPO or other implementing agency to show that it has adequate 

personnel and funding to implement the substitute or additional TCM? 

4.2 What is necessary for an MPO or other implementing agency to demonstrate that there is 

adequate authority under state or local law to implement, monitor and enforce the substitute 

or additional TCM? 

4.3 What agencies would be involved in developing substitute and additional TCMs in 

metropolitan areas? 

4.4 What transportation agency would concur when a TCM substitution or addition is made in a 

donut area or isolated rural area? 

4.5 What is necessary to demonstrate that the collaborative process used to develop substitute 

and additional TCMs included reasonable public notice and opportunity for comment? 

4.6 How and when do the involved agencies indicate their concurrence on the substitution or 

addition? 

4.7 Who must concur for EPA on the substitution or addition of TCMs? 

4.8 What action will EPA take to incorporate the substitute or additional TCM into the codified 

SIP? 

Appendix A: Clean Air Act Section 176(c)(8) -- Substitution and Addition of Transportation 

Control Measures in Approved SIPs.......................................................................19 

Appendix B: Clean Air Act Section 108 -- Transportation Control Measures.............................21 

Appendix C: Example of How to Substitute a TCM Using Clean Air Act Section 176(c)(8).....23 

Appendix D: Example of How to Add a TCM to an Approved SIP Using Clean Air Act 

Section 176(c)(8).....................................................................................................29 

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Section 1: Introduction 

1.1 What is the purpose of this guidance? 

The purpose of this document is to provide nonattainment and maintenance areas with guidance 

on implementing the transportation control measure (TCM) substitution and addition provision 

contained in the Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for 

Users (SAFETEA-LU). SAFETEA-LU, which was signed into law on August 10, 2005, revised 

a number of aspects of the Clean Air Act’s section 176(c) transportation conformity provisions. 

In addition to amendments to the transportation conformity provisions, SAFETEA-LU also 

added a provision to section 176(c) to allow states to substitute or add TCMs into approved state 

implementation plan (SIPs) without the standard SIP revision process.1 2 Under this Clean Air 

Act provision, states are no longer required to include a TCM substitution mechanism in their 

SIPs in order to expedite the process for making TCM substitutions. The provision also provides 

a streamlined process for adding TCMs to an approved SIP. 

EPA revised the transportation conformity rule (40 CFR parts 51 and 93) on January 24, 2008 

(73 FR 4419) to address the transportation conformity-related Clean Air Act amendments made 

by SAFETEA-LU. EPA determined that it was not necessary to promulgate regulations in order 

to successfully implement the TCM substitution and addition statutory provision. (73 FR 4432) 

We are issuing this guidance to assist areas in making TCM substitutions and additions. This 

guidance document supersedes the guidance on TCM substitutions and additions that was 

included in the guidance document titled, “Interim Guidance for Implementing the 

Transportation Conformity Provisions in the Safe, Accountable, Flexible, Efficient 

Transportation Equity Act: A Legacy for Users” that was issued on February 14, 2006.3 

Areas are likely to use this statutory process either to make a TCM substitution in an approved 

SIP or to add a TCM to an approved SIP because the Clean Air Act process will take less time to 

complete than a standard SIP revision. A standard SIP revision requires rulemaking by both the 

state air agency and by EPA to complete either a TCM substitution or addition and therefore 

takes more time to complete than the streamlined Clean Air Act process. 

For example, a metropolitan planning organization (MPO) that is beginning work on its next 

conformity determination may find that a TCM in the area’s approved SIP has become delayed. 

In order for the MPO to both comply with the transportation conformity rule’s requirements for 

timely implementation of TCMs (40 CFR 93.113) and to complete its conformity determination 

as scheduled, the MPO may use the Clean Air Act process to replace the delayed SIP TCM with 

a new TCM. 

An area would also be interested in this guidance if it is considering adding a new TCM to the 

SIP through this more streamlined process. 

1

 The statutory text of Clean Air Act section 176(c)(8) is included in Appendix A of this guidance document. 2

 The standard SIP revision process requires notice and comment rulemaking by both the state air agency and EPA 

in order for the state to revise its SIP and for EPA to approve the revision. 3

 It should be noted that the original TCM substitution guidance that was issued on April 7, 2004 was previously 

withdrawn when EPA issued the SAFETEA-LU interim conformity guidance in February 2006. 

1
There are limited cases where using either the TCM substitution or addition process would not 

be appropriate. For example, if a state needed to increase the amount of emissions reductions 

attributed to TCMs in a control strategy SIP or maintenance plan, it could not accomplish its goal 

solely through the Clean Air Act process to substitute or add TCMs to an approved SIP because 

the Clean Air Act process does not provide a streamlined process for revising control strategy 

SIPs or maintenance plans. The state could use the Clean Air Act process to substitute or add 

new TCMs to its SIP; however, as discussed in Questions 2.12 and 3.4, the state would also need 

to complete a standard SIP revision to revise the relevant control strategy SIP or maintenance 

plan and EPA would need to approve that revision in order to incorporate the additional 

emissions reductions from the substitute or additional TCM into the SIP in order to accomplish 

the state’s goal of increasing the amount of emissions reductions attributable to TCMs. Other 

situations where it would not be appropriate to use the TCM substitution process are discussed in 

Questions 2.6 and 2.8. 

TCMs can still be substituted or added to an area’s SIP through the normal SIP revision process, 

if desired or when necessary. 

1.2 What TCMs are addressed by Clean Air Act section 176(c)(8) and this guidance 

document? 

Clean Air Act section 176(c)(8) and this guidance document pertain to TCMs that apply, or will 

apply once included in the SIP, for conformity. TCMs that apply for conformity are those in 

approved SIPs that affect vehicle use or travel. Section 93.101 of the transportation conformity 

rule defines a TCM as: 

any measure that is specifically identified and committed to in the applicable 

implementation plan, including a substitute or additional TCM that is incorporated into 

the applicable SIP through the process established in CAA section 176(c)(8), that is 

either one of the types listed in CAA section 108(f), or any other measure for the purpose 

of reducing emissions or concentrations of air pollutants from transportation sources by 

reducing vehicle use or changing traffic flow or congestion conditions. Notwithstanding 

the first sentence of this definition, vehicle technology-based, fuel-based, and 

maintenance-based measures which control the emissions from vehicles under fixed 

traffic conditions are not TCMs for the purposes of this subpart. 

We have included the list of measures from Clean Air Act section 108(f) in Appendix B of this 

guidance document. 

Similar types of measures that are included only in an area’s transportation plan and 

transportation improvement program (TIP) and not in the area’s approved SIP are not considered 

TCMs for the purposes of conformity. Because they are not in the SIP, they can be changed 

without either a standard SIP revision or without using the process in Clean Air Act 176(c)(8). 

Furthermore, because vehicle technology-based measures (including diesel retrofit projects, 

vehicle fuel-related programs, and vehicle inspection and maintenance programs) are specifically 

excluded as TCMs under the transportation conformity rule’s TCM definition, these types of 

2
programs cannot be substituted or added into a SIP using the process in Clean Air Act section 

176(c)(8). 

1.3 What are the transportation conformity rule’s requirements for timely implementation 

of TCMs? 

Transportation conformity is required, under Clean Air Act section 176(c), to ensure that 

federally supported highway and transit project activities are consistent with (“conform to”) the 

purpose of the SIP. Conformity to the purpose of the SIP means that transportation activities 

will not cause new air quality violations, worsen existing violations, or delay timely attainment 

of the relevant national ambient air quality standards (NAAQS or “standards”). 

Clean Air Act section 176(c)(2)(B) and section 93.113 of the transportation conformity rule (40 

CFR) require that TCMs in an approved SIP that are eligible for federal funding under title 23 

U.S.C. or under the Federal Transit Laws (Title 49 U.S.C.) must be implemented on the schedule 

established in the SIP. If a TCM falls behind schedule and the area still intends to implement it, 

the MPO must demonstrate that past obstacles to implementation have been identified and have 

been overcome and that state and local agencies with funding authority are giving the delayed 

TCM maximum priority, according to 40 CFR 93.113(c)(1). If the area no longer wants to 

implement a delayed TCM, the area can either use the standard SIP revision process to revise the 

SIP or use the Clean Air Act section 176(c)(8) TCM substitution process to remove the delayed 

TCM from the SIP and to replace it in the SIP with a new TCM. It should be noted that the 

original TCM remains in the approved SIP and subject to the conformity rule’s timely 

implementation requirements until either the replacement TCM is adopted through the Clean Air 

Act substitution process or EPA approves the SIP revision in cases where an area chooses that 

approach.4 

1.4 Is a conformity determination or a SIP revision required when a substitution is made 

or when a TCM is added to the SIP? 

No, neither a conformity determination nor a SIP revision is required when an area makes a 

substitution or adds a new TCM to the approved SIP using the Clean Air Act section 176(c)(8) 

process. Clean Air Act section 176(c)(8)(D) specifically states that the substitution or addition 

of a TCM does not require a new conformity determination or SIP revision. However, if the 

transportation plan and/or TIP need to be amended in order to implement the substitute or 

additional TCM, the applicable United States Department of Transportation (DOT) 

transportation planning requirements (23 CFR 450 and 49 CFR 613) would have to be met. If an 

MPO is making other changes to its transportation plan and/or TIP in addition to a TCM 

substitution or addition, and, if these other changes would require a plan and/or TIP amendment, 

a conformity determination would be required. In such situations the relevant EPA and DOT 

offices are available to assist the MPO to ensure that all transportation conformity and 

transportation planning requirements are met. 

1.5 Does this guidance create new requirements? 

4

 The course of action to be taken if a TCM in an approved SIP falls behind schedule must be determined through 

interagency consultation, per 40 CFR 93.105(c)(1)(iv). 

3
No, this guidance is based on the requirements for transportation control measure substitutions 

and additions contained in Clean Air Act section 176(c)(8) and does not create any new 

requirements. This guidance merely explains how to implement those TCM substitution and 

addition-related provisions and any other related requirements. 

The statutory provisions and the US Environmental Protection Agency (EPA) regulations 

described in this document contain legally binding requirements. This document is not a 

substitute for those provisions or regulations, nor is it a regulation itself. Thus, it does not 

impose legally binding requirements on EPA, DOT, states, or the regulated community, and may 

not apply to a particular situation based upon the circumstances. EPA retains the discretion to 

adopt approaches on a case-by-case basis that may differ from this guidance, but still comply 

with the statute and SIP and conformity regulations. Any decisions regarding a particular TCM 

substitution or addition will be made based on the statute and regulations, after appropriate 

public input and rulemaking procedures where applicable. This guidance may be revised 

periodically without public notice. 

1.6 Who can I contact for more information? 

For specific questions concerning a particular nonattainment or maintenance area, please contact 

the SIP or transportation conformity staff person responsible for your state at the appropriate 

EPA regional office. A listing of EPA regional offices, the states they cover, and contact 

information for EPA regional conformity staff can be found at the following website: 

http://www.epa.gov/otaq/stateresources/transconf/contacts.htm . 

General questions about this guidance can be directed to: 

Rudy Kapichak at EPA’s Office of Transportation and Air Quality, 

kapichak.rudolph@epa.gov or 734-214-4574. 

1.7 Where can I find more information on the web? 

Additional information on the transportation conformity rule and associated guidance can be 

found on EPA’s website at: http://www.epa.gov/otaq/stateresources/transconf/index.htm . 

4
Section 2: Substituting Transportation Control Measures in an Approved SIP 

2.1 When can states use the TCM substitution provision in the Clean Air Act? 

Nonattainment and maintenance areas that do not have TCM substitution mechanisms in their 

approved SIPs have been able to rely on this statutory mechanism to make TCM substitutions 

since August 10, 2005, when SAFETEA-LU was signed into law. 

Several nonattainment and maintenance areas adopted TCM substitution mechanisms in their 

approved SIPs prior to SAFETEA-LU’s enactment.5 These areas must continue to use their SIPapproved TCM substitution mechanisms in addition to the new statutory provision as applicable 

to make substitutions. However, there may be conflicts between an already approved 

mechanism and Clean Air Act section 176(c)(8). In the event of such a conflict, the area would 

follow the Clean Air Act requirements. EPA will work with areas with approved mechanisms on 

a case-by-case basis to answer any questions. These areas may revise their SIPs to remove the 

approved TCM substitution mechanism, and rely solely on the federal statute for future actions 

once EPA approves the SIP revision. 

2.2 What does the Clean Air Act require in order for a TCM substitution to occur? 

For a TCM in an approved SIP to be removed and replaced with a substitute TCM, the Clean Air 

Act requires that: 

• the substitute TCM(s) must achieve equal or greater emissions reductions; 

• the substitute TCM(s) must be implemented on a schedule that is consistent with the 

schedule for the TCM(s) being removed from the SIP; or, if the implementation date has 

passed for the TCM(s) being replaced, the replacement TCM must be implemented as 

soon as practicable but not later than the date on which emissions reductions from the 

TCM(s) are necessary to achieve the purpose of the SIP; 

• the substitute TCM(s) must be accompanied by evidence of adequate personnel, and 

funding and authority under state or local law to implement, monitor and enforce the 

TCM(s); 

• the substitute TCM(s) must be developed through a collaborative process that includes 

participation by all affected jurisdictions (state and local air pollution control agencies 

and state and local transportation agencies such as the MPO, state DOT, and transit 

providers); consultation with EPA; and reasonable notice and opportunity for public 

comment; and 

• the equivalency of the substitute TCM(s) must be concurred on by the state air pollution 

control agency, the MPO,6 and EPA. That is, EPA, the state air agency, and the MPO 

must all agree that on the estimated emissions reductions from the substitute TCM(s) and 

agree that the estimated emissions reductions equal or surpass those that would have 

resulted from the original TCM(s) in the approved SIP. 

5

 Portland, OR; Albuquerque, NM; and Texas; have TCM substitution mechanisms in their approved SIPs. 6

 The state DOT would concur on TCM substitutions in isolated rural areas because these areas do not have MPOs. 

See question 4.4 for more information. 

5
The remainder of this section and Section 4 below contain further details on how to comply with 

these specific requirements. Appendix C contains an example of how to carry out a TCM 

substitution using the process in Clean Air Act section 176(c)(8). 

2.3 What additional information should be provided to support a TCM substitution? 

The material prepared to support a substitution should clearly identify and describe the original 

TCM in the approved SIP and the substitute TCM. The substitute TCM should meet all of the 

requirements of Clean Air Act section 110 and EPA’s 1989 TCM SIP Guidance (EPA 450/2-89-

020), which can be found at: 

http://www.epa.gov/otaq/stateresources/policy/transp/tcms/state_plan_guidance.pdf. 

The documentation for each TCM substitution must include all of the information necessary to 

demonstrate that the Clean Air Act requirements are met including the demonstration that the 

substitute TCM provides equivalent or greater emissions reductions. The documentation for 

each substitution should also include: 

1) the name of the original TCM in the approved SIP that is proposed to be replaced; 

2) the name of the proposed substitute TCM; 

3) a brief but thorough description of both the original and substitute TCMs including 

their locations and implementing agencies; 

4) the steps and schedule for completing and operating the substitute TCM; and 

5) a brief explanation of why the substitution is necessary. 

2.4 How does a state air agency, MPO or other transportation agency demonstrate that a 

substitute TCM provides equivalent emissions reductions? 

In order to demonstrate that the new TCM provides equal or greater emissions reductions, the 

emissions benefits of the substitute TCM must be analyzed in a manner consistent with the 

planning assumptions and modeling used for analysis of the existing TCMs in the approved SIP, 

unless more recent planning assumptions and/or a newer emissions model are now available. If 

updated assumptions and/or a newer emissions model are available, the relevant state or local 

agency must recalculate the emissions benefits of the original TCM and use that emissions 

estimate in determining if the substitute TCM provides equivalent or greater emissions 

reductions as required by Clean Air Act section 176(c)(8)(A)(i). If the SIP relied upon emissions 

reductions from a TCM to address a localized violation, a new hot-spot analysis must be done to 

ensure that the SIP continues to fulfill its purpose and meet all applicable SIP requirements.7 If 

such a hot-spot analysis were necessary it would be completed for SIP purposes not to fulfill the 

transportation conformity rule’s project-level requirements. 

In determining whether or not a substitute TCM provides equivalent or greater emissions 

reductions, the agency preparing the analysis should document that the substitute TCM provides 

emissions reductions that are: 

7 Applicable requirements may include approved methodologies such as those specified in 40 CFR part 51, 

Appendix W (Guideline on Air Quality Models) for CO analyses or applicable requirements for PM10 and PM2.5 

analyses. 

6
$ permanent for the time period relied upon in the applicable SIP; 

$ for the same time of year (e.g., during the winter carbon monoxide season) or during a 

specific time of day (e.g., the morning or evening rush hour) relied upon in the applicable 

SIP; 

$ for the same pollutant or precursor as the original SIP TCM, unless the area has a SIPapproved trading mechanism that would allow trading between precursors or between a 

pollutant and its precursor(s); and 

$ for the same geographic location, if such a location is identified as critical for the 

emissions reductions in the applicable SIP. For example, if a TCM was included in an 

approved SIP to address a specific local air quality problem such as a violation of the CO 

standard, the substitute TCM would have to be implemented in a location to address the 

same violation. Alternatively, if a facility such as a park-and-ride lot was included in the 

SIP to serve a particular community or development project, the substitute TCM would 

need to be located so that it serves the same community or development project. 

In order to ensure equivalent or greater reductions in all cases, the agency doing the analysis 

must also consider whether or not the substitution will have an effect on any other SIPs for the 

area. For example, if a TCM is relied upon in more than one SIP (e.g., a TCM provides both 

VOC and NOx emissions reductions in an approved ozone attainment demonstration and 

provides carbon monoxide emissions reductions in an approved carbon monoxide maintenance 

plan), the emissions analysis that is performed for the substitution would need to demonstrate 

that the substitute TCM provides equivalent or greater emissions reductions of all of the same 

pollutants and precursors as the original TCM in the approved SIPs. Another example could 

occur if an area is nonattainment or maintenance for several pollutants and a TCM is included in 

an approved SIP for one pollutant but not explicitly included in the approved SIP or maintenance 

plan for other pollutants. This situation is discussed in Question 2.9. 

Nonattainment and maintenance areas must meet all relevant Clean Air Act requirements. 

Nonattainment areas must continue to meet the Clean Air Act’s requirements for implementation 

of Reasonably Available Control Measures (RACM);8 and serious PM10 nonattainment areas 

must continue to meet requirements for implementation of Best Available Control Measures 

(BACM).9

 Serious, severe and extreme ozone areas and moderate and serious carbon monoxide 

areas that have adopted TCMs to comply with Clean Air Act sections 182(c)(5), 182(d)(1)(A), 

182(e)(4), 187(a)(2)(A) or 187(b)(2) may substitute TCMs through the Clean Air Act 

substitution process; however, they must continue to comply with the Clean Air Act 

requirements that apply in ozone and carbon monoxide nonattainment areas. 

8

 RACM requirements do not apply in maintenance areas. 9

 Provided that all applicable RACM and BACM requirements are met, EPA believes that TCMs substituted through 

the use of the Clean Air Act TCM substitution mechanism would fulfill the requirements of Clean Air Act section 

193 because the substitute TCMs provide equivalent emission reductions and therefore would not interfere with 

reasonable further progress or attainment. The requirements in Clean Air Act section 110(l) would not apply to 

substitutions made through this mechanism because section 110(l) only applies to control measures approved into 

the SIP by EPA and these substitutions do not require EPA SIP approval. 

7
2.5 If the SIP does not include any emissions reductions from a TCM, can it be substituted 

with another TCM without an analysis? 

No. Some approved SIPs include TCMs for which no emissions reduction credit was claimed. 

If such a TCM is to be replaced through a TCM substitution, an emissions analysis must be 

performed for both the existing SIP-approved TCM and the proposed substitute TCM in order to 

demonstrate that there will be an equivalent or greater reduction in emissions as a result of the 

substitution, as required by Clean Air Act section 176(c)(8)(A)(i). 

2.6 Can the TCM substitution process be used to remove a TCM from the applicable SIP 

without providing a substitute measure? 

No. The Clean Air Act section 176(c)(8) TCM substitution process only provides legal authority 

for an area to remove a TCM from the applicable SIP if it is replaced with a TCM that provides 

equivalent or greater emissions reductions, even if these reductions are not claimed in the SIP’s 

demonstration. TCMs can be removed from an applicable SIP without substitution through a 

standard SIP revision. Such a SIP revision would have to be shown to meet Clean Air Act 

section 110(l) requirements (e.g., the area would have to show that removal of the TCM would 

not interfere with any applicable requirement concerning attainment and reasonable further 

progress, or any other applicable Clean Air Act requirement). 

2.7 If a substitute TCM cannot be implemented on the same schedule as the original TCM, 

what is necessary in order to fulfill the Clean Air Act requirement that “the replacement 

TCM must be implemented as soon as practicable but not later than the date on which 

emissions reductions are necessary to achieve the purpose of the implementation plan?” 

If it is not possible for the substitute TCM to be implemented by the same deadline as the 

original TCM, the substitute TCM would have to be implemented as expeditiously as practicable 

so that emissions reductions can be achieved by the year required by the SIP. For example, 8-

hour ozone nonattainment areas classified as moderate have an attainment date of June 2010. In 

such an area, if the TCM being replaced was to be implemented in 2008 and was included in the 

area’s 8-hour ozone attainment demonstration, the substitute TCM should be fully implemented 

no later than the beginning of the 2009 ozone season (i.e., the final complete ozone season before 

the June 2010 attainment date). In this example, the substitute TCM would be implemented by 

the time reductions are needed to support the SIP, in this case by the beginning of the 2009 

ozone season. 

2.8 Can the substitution process be used if the substitute TCM could not be implemented 

until after the date on which emissions reductions are necessary to achieve the purpose of 

the implementation plan? 

No, reliance on the TCM substitution provision would not be appropriate in the case where both 

the implementation date for the original TCM and SIP milestone date have passed. The TCM 

substitution process cannot be used for a given substitution if it would interfere with any 

applicable requirement for reasonable further progress, timely attainment, or maintenance of any 

NAAQS. For example, if a TCM that was included in an attainment demonstration for a 

8
moderate 8-hour ozone nonattainment area was to be in place at the beginning of 2009 and 

became delayed, it would not be appropriate to use the TCM substitution mechanism to replace it 

with a TCM that could not be implemented until 2011. In this case, a standard SIP revision 

would be required to address the attainment demonstration as well as the substitute TCM, to 

ensure that sufficient control measures are in place to demonstrate timely attainment. 

2.9 How would the TCM substitution process work in an area that is nonattainment 

and/or maintenance for two or more pollutants, where the original TCM is included in the 

SIP for only one pollutant? 

An area could use the TCM substitution process to replace a TCM that is included in an 

approved SIP for one pollutant but not explicitly included in the approved SIP or maintenance 

plan for other pollutants if certain conditions are met. The substitution must meet all of the 

requirements of Clean Air Act section 176(c)(8). The documentation for the substitution must 

include an emissions analysis that demonstrates that the substitute TCM provides equivalent or 

greater emissions reductions for the same pollutants and precursors that original TCM provided 

in the applicable SIP. The material must also document that the substitution will not result in 

increased emissions of the other pollutants and precursors for which the area is designated 

nonattainment or maintenance. This additional information for the other pollutants and/or 

precursors is necessary to demonstrate that the substitution will not interfere with any applicable 

requirement concerning attainment, reasonable further progress, maintenance or any other 

applicable Clean Air Act requirement that applies to the other pollutants for which the area is 

designated nonattainment or maintenance. If the substitution does not include information to 

document that it provides equivalent or greater emissions reductions for all pollutants for which 

the area is designated nonattainment or maintenance, the net effect of the substitution could be an 

increase in emissions for the pollutants and/or precursors not addressed in the demonstration, and 

call into question the air quality demonstrations supporting the SIPs for those pollutants. 

2.10 Can the TCM substitution process be used to replace a TCM in an approved SIP for 

an air quality standard that has been revoked if the area remains nonattainment and/or 

maintenance for other pollutants? 

Yes, a nonattainment or maintenance area could use the TCM substitution process to replace a 

TCM in an approved SIP for an air quality standard that has been revoked if certain conditions 

are met. First, the substitution would have to meet any applicable anti-backsliding requirements 

associated with the revoked air quality standard. Second, the substitution must meet all of the 

requirements of Clean Air Act section 176(c)(8). The documentation for the substitution must 

include an emissions analysis that demonstrates that the substitute TCM provides equivalent or 

greater emissions reductions for the same pollutants and precursors that original TCM provided 

in the applicable SIP. The material must also document that the substitution will not result in 

increased emissions of the other pollutants and precursors for which the area is designated 

nonattainment or maintenance. This additional information for the other pollutants and/or 

precursors is necessary to demonstrate that the substitution would not interfere with any 

applicable requirement concerning attainment and reasonable further progress, or any other 

applicable Clean Air Act requirement that applies to the other pollutant(s) for which the area is 

designated nonattainment or maintenance. If the substitution does not include information to 

9
document that it provides equivalent or greater emissions reductions for all pollutants for which 

the area is designated nonattainment or maintenance, the net effect of the substitution could be an 

increase in emissions for the pollutants and/or precursors not addressed in the demonstration, 

and call into question any air quality demonstrations supporting the SIPs for those pollutants. 

EPA addressed this situation as it pertains to requirements for the timely implementation of 

TCMs contained in 1-hour ozone SIPs in areas that are now designated as nonattainment or 

maintenance for the 8-hour ozone standard in the July 1, 2004 new standards rulemaking. 

Specifically, EPA stated that: 

Section 93.113 of the existing conformity rule requires that transportation 

plans, TIPs, and projects which are not from a conforming plan and TIP 

must provide for the timely implementation of TCMs from an approved 

SIP. EPA notes that today's final rule does not change the implementation 

of these requirements for any existing or new nonattainment or 

maintenance area, including 8-hour nonattainment areas that have 

approved 1-hour SIPs that contain TCMs. 

Clean Air Act section 176(c) requires that TCMs in approved SIPs be 

implemented in a timely manner according to the schedules in the SIP. 

This requirement is not contingent on what type of SIP, pollutant, or 

standard for which the approved TCM was established. Conformity 

determinations for any pollutant and standard must provide for the timely 

implementation of TCMs in approved SIPs, including TCMs in approved 

SIPs for the 1-hour ozone standard after that standard is revoked. (69 FR 

40013) 

Any area considering such changes should consult with the EPA regional office in order to 

determine how best to meet the requirements described above. 

2.11 When can an MPO make a conformity determination based on a substitution? 

An MPO can make a conformity determination as soon as the state air pollution control agency, 

the MPO and EPA have concurred on the substitution.10 The MPO does not have to wait until 

after the state air agency has submitted the substitute TCM to EPA for incorporation into the 

codified applicable SIP before it makes a conformity determination. At this point the MPO 

would rely on the substitute TCM to meet the transportation conformity rule’s requirements for 

timely implementation and may include the emissions reductions benefits of the substitute TCM 

in the regional emissions analysis for the area. If the substitute TCM provides greater emissions 

reductions than the original SIP-approved TCM, the MPO would be able to use those extra 

emissions reductions in its regional emissions analysis. Once all of these agencies have 

concurred, the substitute TCM is considered to be adopted. Once adopted under this process, the 

substitute TCM becomes part of the federally enforceable SIP for the area. The adoption of the 

substitute TCM also serves to remove the original TCM from the federally enforceable SIP. 

10 However, it should be noted that substituting a TCM in a SIP does not require a new conformity determination – 

see Question 1.4 for more information. 

10
Therefore, once the adoption occurs, the original TCM is no longer subject to Clean Air Act SIP 

and transportation conformity rule requirements for timely implementation of TCMs in approved 

SIPs. Subsequent to adoption, EPA will incorporate the substitute or new TCM(s) into the 

federal codification of the SIP to clarify for the public which TCMs are part of the federally 

enforceable SIP. 

If the transportation plan and/or TIP need to be amended in order to implement the substitute 

TCM, DOT’s transportation planning requirements (23 CFR 450 and 49 CFR 613) would have 

to be met. Additionally, if the MPO is making other changes to its transportation plan and/or 

TIP in addition to a TCM substitution or addition, and, if these other changes would require a 

plan and/or TIP amendment, a conformity determination would be required. In such situations 

the relevant EPA and DOT offices are available to assist the MPO to ensure that all 

transportation conformity and transportation planning requirements are met. 

2.12 What must a state air agency do if a substitute TCM provides greater emissions 

reductions than the original TCM and the agency wants to incorporate the additional 

reductions into its control strategy SIP or maintenance plan? 

A state air agency is not required to revise a SIP to incorporate any additional reductions beyond 

those accounted for in the existing SIP. However, if such a situation occurs, the state air agency 

would need to revise its control strategy SIP or maintenance plan and associated motor vehicle 

emissions budgets, and EPA would need to approve such a SIP revision in order for the state to 

incorporate these additional emissions reductions in the area’s control strategy SIP or 

maintenance plan. This would also apply if the SIP did not include any emissions reductions 

from the original TCM, but the state now wants to include the emissions reductions from the 

substitute TCM in the relevant control strategy SIP or maintenance plan. These actions would be 

separate from and in addition to the TCM substitution process. 

11
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12
Section 3: Adding Transportation Control Measures to an Approved SIP 

3.1 What is required in order for a new TCM to be added to an area’s approved SIP 

through the process established in Clean Air Act section 176(c)(8)? 

In order for an area to add a new TCM to an approved SIP through the process established in 

Clean Air Act section 176(c)(8): 

• the new TCM must be accompanied by evidence of adequate personnel, and funding and 

authority under state or local law to implement, monitor and enforce the TCM; 

• the new TCM must be developed through a collaborative process that includes 

participation by all affected jurisdictions and agencies (e.g., state and local air pollution 

control agencies and state and local transportation agencies); consultation with EPA; and 

reasonable notice and opportunity for public comment; and 

• the MPO, the state air pollution control agency, and EPA must concur on the addition of 

the new TCM to the SIP. 

Section 4 of this guidance document below contains further details on how to comply with these 

specific requirements. Appendix D contains an example of how to carry out a TCM addition 

using the statutory process. 

It should be noted that TCMs can still be added to an area’s SIP through the standard SIP 

process, if desired. 

3.2 What additional information should be provided to support the addition of a TCM to 

an approved SIP? 

The material prepared to support a TCM addition should clearly identify and describe the new 

TCM to be added to the approved SIP. The additional TCM should meet all of the requirements 

of Clean Air Act section 110 and EPA’s 1989 TCM SIP Guidance (EPA 450/2-89-020). The 

documentation for each TCM addition must include all of the information necessary to 

demonstrate that the Clean Air Act requirements for TCM additions are met. The documentation 

for each TCM to be added to the approved SIP should also include: 

1) the name of the proposed additional TCM; 

2) a brief but thorough description of the additional TCM including its location and 

implementing agency; 

3) the steps and schedule for completing and operating the additional TCM; and 

4) a brief explanation of why the addition is being made. 

3.3 Can all nonattainment and maintenance areas add TCMs to their approved SIPs? 

Yes, any nonattainment or maintenance area can add new TCMs to its approved SIP by 

following the criteria contained in Clean Air Act section 176(c)(8)(A)(iii)-(v) and described in 

Question 3.1 above. It is not necessary for a given area to already have TCMs in its approved 

SIP in order to add new TCMs through this statutory process. However, if the transportation 

plan and/or TIP need to be amended in order to implement the additional TCM, DOT’s 

13
transportation planning requirements (23 CFR 450 and 49 CFR 613) would have to be met. 

Additionally, if the MPO is making other changes to its transportation plan and/or TIP in 

addition to a TCM substitution or addition, and, if these other changes would require a plan 

and/or TIP amendment, a conformity determination would be required. In such situations the 

relevant EPA and DOT offices are available to assist the MPO to ensure that all transportation 

conformity and transportation planning requirements are met. 

3.4 What must a state air agency do if it wants to incorporate the emissions reductions 

from an additional TCM into its control strategy SIP or maintenance plan? 

If the state air agency wants to incorporate the emissions reductions from the additional TCM 

into the applicable SIP, the agency would need to revise its control strategy SIP or maintenance 

plan and associated motor vehicle emissions budgets, and EPA would need to approve such a 

SIP revision in order for the state to incorporate the emissions reductions from the additional 

TCM into the area’s control strategy SIP or maintenance plan. These actions would be separate 

from and in addition to the TCM addition process. 

14
Section 4: Process Requirements That Apply When Substituting or Adding 

Transportation Control Measures to an Approved SIP 

4.1 What is necessary for an MPO or other implementing agency to show that it has 

adequate personnel and funding to implement the substitute or additional TCM? 

TCMs that are included in a metropolitan area’s transportation plan and TIP need to meet all 

applicable requirements in DOT’s transportation planning regulations, including the 

transportation plan and TIP fiscal constraint requirement (23 CFR 450 and 49 CFR 613). 

Therefore, inclusion of the substitute or additional TCM in a fiscally constrained transportation 

plan and TIP generally would serve as sufficient evidence that adequate resources are available 

to implement the TCM. In the case of an isolated rural area11 or donut area12, inclusion of the 

substitute or additional TCM in the Statewide Transportation Improvement Program (STIP) 

would indicate that the implementing agency had resources to carry out the project. It is possible 

that situations will arise where an MPO would need to make a TCM substitution and revise its 

TIP to remove the original TCM and add the substitute TCM simultaneously. In such situations, 

the MPO should use the interagency consultation process to reach agreement on the details of 

these simultaneous actions. 

However, if the substitute or additional TCM is not federally funded or is not part of the 

transportation plan and TIP or STIP, the implementing agency must provide additional 

information on the availability and commitment of adequate resources as necessary to implement 

the new TCM in order to meet the requirements of Clean Air Act section 176(c)(8)(A)(iii). For 

example, the implementing agency could provide documentation that funding has been 

authorized to implement the substitute or additional TCM, and/or information describing the 

agency’s plan for providing staff to implement the TCM as planned. 

4.2 What is necessary for an MPO or other implementing agency to demonstrate that there 

is adequate authority under state or local law to implement, monitor and enforce the 

substitute or additional TCM? 

Generally, inclusion of the substitute or additional TCM in a metropolitan area’s transportation 

plan and TIP, or in the case of an isolated rural area or donut area, inclusion of the substitute or 

additional TCM in the STIP, would indicate that the implementing agency had legal authority to 

carry out the project. However, if the TCM is not federally funded or is not part of the 

transportation plan and TIP or STIP, the implementing agency must provide additional 

information on its legal authority to implement the substitute or additional TCM in order to meet 

the requirements of Clean Air Act section 176(c)(8)(A)(iii). For example, the implementing 

11 Isolated rural nonattainment and maintenance areas are areas that do not contain or are not part of any 

metropolitan planning area as designated under the transportation planning regulations. Isolated rural areas do not 

have Federally required metropolitan transportation plans or TIPs and do not have projects that are part of the 

emissions analysis of any MPO's metropolitan transportation plan or TIP. Projects in such areas are instead included 

in statewide transportation improvement programs. These areas are not donut areas. (40 CFR 93.101) 

12 Donut areas are geographic areas outside a metropolitan planning area boundary, but inside the boundary of a 

nonattainment or maintenance area that contains any part of a metropolitan area(s). These areas are not isolated 

rural nonattainment and maintenance areas. (40 CFR 93.101) 

15
agency could provide a citation to the applicable state or local law that authorizes it to implement 

such projects, or discuss how implementing such a TCM would fall within its general authority. 

Because the substitute or additional TCM becomes part of the approved SIP for the area, Clean 

Air Act sections 113 and 179(a) grant EPA the authority to enforce the implementation of such a 

TCM. Implementation of substitute and additional TCMs may also be enforced by citizen suits 

under Clean Air Act section 304. 

4.3 What agencies would be involved in developing substitute and additional TCMs in 

metropolitan areas? 

The agencies involved in the collaborative process used to develop substitute and additional 

TCMs would be similar to the group that participates in the area’s conformity interagency 

consultation process. The involved agencies must include the state air agency, the MPO, and the 

EPA regional office because Clean Air Act section 176(c)(8)(B)(i) requires their concurrence. 

Other agencies that may be involved include the state and local transportation agencies and local 

air quality agencies. Additionally, all of the jurisdictions affected by the substitution or addition 

that is being considered should be involved. The process should also include relevant FHWA 

and FTA field offices. Early consultation with federal agencies is essential to facilitate 

subsequent concurrence on each substitution by EPA, and conformity determinations based in 

part on timely implementation of substituted TCMs by FHWA and FTA. Please refer to 

Question 4.4 for additional information on which transportation agencies must concur on TCM 

substitutions and additions in donut areas and in isolated rural areas. 

4.4 What transportation agency would concur when a TCM substitution or addition is 

made in a donut area or isolated rural area? 

For donut areas (i.e., those areas within a nonattainment or maintenance area but outside the 

metropolitan planning area), the TCM substitution process should be implemented as above and 

the MPO associated with the donut area should concur in any substitution or addition of a TCM 

to an approved SIP.13 

For isolated rural areas (i.e., those nonattainment or maintenance areas that do not contain any 

metropolitan area), this provision should be implemented as above, except the state DOT should 

concur on the substitution or addition because there is no MPO associated with such an area. 

In either case the state air agency and EPA regional office would concur on any TCM 

substitution or addition as described in Question 4.3 and elsewhere in this document. 

13 It would also be acceptable for the state DOT to concur on a TCM substitution or addition in a donut area instead 

of the MPO, if that is consistent with local process for determining conformity in the relevant nonattainment or 

maintenance area. 

16
4.5 What is necessary to demonstrate that the collaborative process used to develop 

substitute and additional TCMs included reasonable public notice and opportunity for 

comment? 

Reasonable public notice and a public comment period must be provided when a TCM 

substitution or addition is made. Because EPA’s concurrence on a specific substitution or 

addition would be based on EPA’s conclusion that the substitution or addition complies with the 

requirements set forth in Clean Air Act section 176(c)(8), commenters should be made aware 

through the announcement that they may submit comments not only on whether the state should 

concur on the substitution or addition but also on whether EPA should concur with that 

substitution or addition. The public must be provided access to all material relevant to the 

substitution or addition. The public comment process could be carried out either by the state or 

local air quality agency or by the MPO using their existing process for soliciting public comment 

on other documents. The state and/or local air agency should ensure that the TCM substitution 

or addition process complies with all applicable laws and regulations for public participation 

including state or local sunshine laws. Copies of any prepared supporting documentation should 

be provided to the state and local air quality agencies, the MPO, the EPA regional office, the 

FHWA division office, the FTA regional office, and any other relevant state and local agencies. 

All public comments received would be considered and responses documented before 

proceeding with the substitution or addition. Copies of the public comments and responses 

should be provided to the state and local air quality agencies, the MPO, the EPA regional office, 

the FHWA division office, the FTA regional office, and any other relevant state and local 

agencies. 

4.6 How and when do the involved agencies indicate their concurrence on the substitution 

or addition? 

A substitution or addition cannot go into effect unless EPA, the state air agency and the MPO 

have all concurred on the substitution. If the substitution or addition fulfills all of the 

requirements specified in Clean Air Act section 176(c)(8), the state air agency and EPA would 

each indicate its concurrence by sending a letter to the MPO and each other (i.e., the state air 

agency would send its letter to the EPA and vice versa). The MPO would indicate its 

concurrence by resolution of the MPO’s policy board that is made available to the state air 

agency and EPA through the MPO’s routine process. Within 90 days of its concurrence, the 

state air agency must submit the substitute or additional control measure and all supporting 

information to the EPA regional office so that the TCM can be incorporated in the codified 

applicable SIP. 

The consultation process should be used to establish the exact point in the process that 

concurrence will be given so that it meets Clean Air Act requirements. The Clean Air Act 

requires that concurrence by the air agency and EPA occur after equivalency of the substitute 

measure(s) is demonstrated and the SAFETEA-LU conference report clarifies that "adoption 

occurs when the MPO, state air agency and EPA concur that all four of the general requirements 

in subparagraph (A) of the provision have been fulfilled.14" Therefore, concurrence would have 

14 Joint Explanatory Statement of the Committee of Conference, “Section 6011, Transportation Conformity,” p. 

1065. 

17
to occur sufficiently late in the process so that the agencies are sure that all four criteria have 

been met. 

4.7 Who must concur for EPA on the substitution or addition of TCMs? 

Clean Air Act section 176(c)(8) requires concurrence by the Administrator of EPA. However, 

concurrence has been delegated to the EPA Regional Administrator.15 The concurrence may be 

further delegated to the regional air division director. 

4.8 What action will EPA take to incorporate the substitute or additional TCM into the 

codified SIP? 

Once a state has submitted the substitute or additional TCM to EPA for incorporation in the 

codified applicable SIP, EPA will update the Code of Federal Regulations (CFR) to reflect the 

changes to the SIP. This would be done through the publication of a notice in the Federal 

Register. When a state that has been converted to the “SIP notebook system”

16 substitutes or 

adds a non-regulatory TCM, EPA will publish an informational notice in the rules section of the 

Federal Register to update the CFR. In states that have not yet been converted to the notebook 

system, or for TCMs that require regulations to be implemented, EPA would need to take a final 

action in the Federal Register to incorporate the substitute or additional TCM into the CFR. 

When EPA takes a final action to incorporate the specific substitute or additional TCM into the 

CFR, it will do so without additional notice-and-comment rulemaking. EPA believes that it 

would have good cause under the Administrative Procedure Act to take these actions without 

additional opportunity for public comment because the substitution or addition was made 

through the process included in Clean Air Act section 176(c)(8), and because the public would 

have had the opportunity to comment on the specific substitution or addition during the public 

comment period on the specific substitution or addition. 

15 On September 29, 2006 the EPA Administrator delegated the authority for concurring on TCM substitutions and 

additions to the Regional Administrators (Delegation of Authority 7-158: Transportation Control Measure 

Substitutions and Additions). 16 The notebook system for compiling SIPs is a process through which EPA revises 40 CFR Part 52 by: 1) revising 

charts listed in the Identification of Plan section; 2) submitting State regulatory revisions for incorporation by 

reference into the SIP by means of a revised annual compilation (generally in a looseleaf notebook) of all State 

regulations listed in these Identification of Plan charts rather than by piecemeal regulation updates; and 3) updating 

the list of non-regulatory measures in the State’s SIP through the use of an informational notice in the rules section 

of the Federal Register. Non-regulatory measures are not incorporated by reference into the Code of Federal 

Regulations; therefore, these materials are maintained in the notebook for the State at the EPA regional office and in 

a notebook maintained in the Office of the Federal Register. 

18
APPENDIX A 

Clean Air Act Section 176(c)(8) 

Substitution and Addition of Transportation Control Measures in Approved SIPs

This appendix includes Clean Air Act section 176(c)(8) which was added to the Clean Air Act by 

SAFETEA-LU. EPA is providing this text for informational purposes only. 

 SECTION 176(c) (8) SUBSTITUTION OF TRANSPORTATION CONTROL MEASURES.— 

(A) IN GENERAL.—Transportation control measures that are specified in an 

implementation plan may be replaced or added to the implementation plan with alternate or 

additional transportation control measures 

(i) if the substitute measures achieve equivalent or greater emissions reductions than the 

control measure to be replaced, as demonstrated with an emissions impact analysis that is 

consistent with the current methodology used for evaluating the replaced control measure in the 

implementation plan; 

(ii) if the substitute control measures are implemented— 

(I) in accordance with a schedule that is consistent with the schedule provided for 

control measures in the implementation plan; or 

(II) if the implementation plan date for implementation of the control measure to 

be replaced has passed, as soon as practicable after the implementation plan date but not later 

than the date on which emission reductions are necessary to achieve the purpose of the 

implementation plan; 

(iii) if the substitute and additional control measures are accompanied with evidence of 

adequate personnel and funding and authority under State or local law to implement, monitor, 

and enforce the control measures; 

(iv) if the substitute and additional control measures were developed through a 

collaborative process that included— 

(I) participation by representatives of all affected jurisdictions (including local air 

pollution control agencies, the State air pollution control agency, and State 

and local transportation agencies); 

(II) consultation with the Administrator; and 

(III) reasonable public notice and opportunity for comment; and 

(v) if the metropolitan planning organization, State air pollution control agency, and the 

Administrator concur with the equivalency of the substitute or additional control measures. 

(B) ADOPTION.— 

(i) Concurrence by the metropolitan planning organization, State air pollution control 

agency and the Administrator as required by subparagraph (A)(v) shall constitute adoption of the 

substitute or additional control measures so long as the requirements of subparagraphs (A)(i), 

(A)(ii), (A)(iii) and (A)(iv) are met. 

(ii) Once adopted, the substitute or additional control measures become, by operation of 

law, part of the State implementation plan and become federally enforceable. 

(iii) Within 90 days of its concurrence under subparagraph (A)(v), the State air pollution 

control agency shall submit the substitute or additional control measure to the Administrator for 

incorporation in the codification of the applicable implementation plan. Notwithstanding any 

19
other provision of this Act, no additional State process shall be necessary to support such 

revision to the applicable plan. 

(C) NO REQUIREMENT FOR EXPRESS PERMISSION.—The substitution or addition of a 

transportation control measure in accordance with this paragraph and the funding or approval of 

such a control measure shall not be contingent on the existence of any provision in the applicable 

implementation plan that expressly permits such a substitution or addition. 

(D) NO REQUIREMENT FOR NEW CONFORMITY DETERMINATION.— The 

substitution or addition of a transportation control measure in accordance with this paragraph 

shall not require— 

(i) a new conformity determination for the transportation plan; or 

(ii) a revision of the implementation plan. 

(E) CONTINUATION OF CONTROL MEASURE BEING REPLACED.—A control 

measure that is being replaced by a substitute control measure under this paragraph shall remain 

in effect until the substitute control measure is adopted by the State pursuant to subparagraph 

(B). 

(F) EFFECT OF ADOPTION.—Adoption of a substitute control measure shall constitute 

rescission of the previously applicable control measure. 

20
APPENDIX B 

Clean Air Act Section 108 

Transportation Control Measures

This appendix includes a list of the types of measures included in Clean Air Act section 108(f)(1) 

that meet the transportation conformity rule’s definition of a TCM. This is not an exhaustive list 

of all of the types of measures that meet the transportation conformity rule’s definition of a 

TCM. 

EPA is providing this list of measures for informational purposes only. 

The following types of measures listed in Clean Air Act section 108(f) meet the transportation 

conformity rule’s definition of a TCM: 

 programs for improved public transit; 

 restriction of certain roads or lanes to, or construction of such roads or lanes for use by, 

passenger buses or high occupancy vehicles; 

 employer-based transportation management plans, including incentives; 

 trip-reduction ordinances; 

 traffic flow improvement programs that achieve emission reductions; 

 fringe and transportation corridor parking facilities serving multiple occupancy vehicle 

programs or transit service; 

 programs to limit or restrict vehicle use in downtown areas or other areas of emission 

concentration particularly during periods of peak use; 

 programs for the provision of all forms of high-occupancy, shared-ride services; 

 programs to limit portions of road surfaces or certain sections of the metropolitan area 

to the use of non-motorized vehicles or pedestrian use, both as to time and place; 

 programs for secure bicycle storage facilities and other facilities, including bicycle lanes, 

for the convenience and protection of bicyclists, in both public and private areas; 

 programs to control extended idling of vehicles; 

 programs to reduce motor vehicle emissions, consistent with title II, which are caused by 

extreme cold start conditions; 

 employer-sponsored programs to permit flexible work schedules; 

 programs and ordinances to facilitate non-automobile travel, provision and utilization of 

mass transit, and to generally reduce the need for single-occupant vehicle travel, as part 

of transportation planning and development efforts of a locality, including programs and 

ordinances applicable to new shopping centers, special events, and other centers of 

vehicle activity; 

 programs for new construction and major reconstructions of paths, tracks or areas solely 

for the use by pedestrian or other non-motorized means of transportation when 

economically feasible and in the public interest; and 

 programs to encourage the voluntary removal from use and the marketplace of pre-1980 

model year light duty vehicles and pre-1980 model light duty trucks. 

21
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22
APPENDIX C 

Example of How to Substitute a TCM Using Clean Air Act Section 176(c)(8) 

This appendix provides an example of how a nonattainment or maintenance area could use the 

Clean Air Act process to substitute a new TCM for an existing SIP-approved TCM that has 

become delayed. 

C.1 Why would a nonattainment or maintenance area need to quickly remove a TCM 

from the approved SIP and replace it with a new one? 

For example, an MPO in a moderate 8-hour ozone nonattainment area begins work on a 

conformity determination that needs to be completed in six months. The 8-hour area is not 

currently nonattainment or maintenance for any other pollutant, since EPA revoked the 1-hour 

ozone standard. To comply with the conformity regulation at 40 CFR 93.113, the MPO reviews 

the status of the four TCMs that were included in the area’s approved 8-hour ozone attainment 

demonstration. During the review, the MPO determines that one of the TCMs is significantly 

behind schedule. The delayed TCM involves the implementation of a high occupancy toll lane 

(“HOT lane”). According to the schedule in the 8-hour attainment demonstration, the HOT lane 

was to open in 2008. However, the MPO determines that the opening will be delayed until 2011, 

which is after the area’s 8-hour ozone attainment date of 2010. 

As required by the transportation conformity rule (40 CFR 93.105(c)(1)(iv)), the MPO and the 

rest of the area’s interagency consultation group discuss the issue at their next meeting. The 

interagency consultation group concludes that it would be impossible to overcome the issues that 

are delaying the implementation of the HOT lane and therefore the best course of action is to 

remove it from the SIP and replace it with a substitute TCM(s). They also decide that because 

the MPO needs to complete the conformity determination in six months, there is not enough time 

to use the standard SIP revision process. Therefore, they will use the Clean Air Act section 

176(c)(8) TCM substitution process, which can be completed in time to allow the MPO to make 

the conformity determination as planned, while ensuring that the SIP continues to achieve its 

intended purpose. 

C.2 How would the area proceed to make the TCM substitution? 

In order to complete the TCM substitution in a timely manner, the MPO and state air agency take 

the following steps. 

Review of the TCM to be removed from the approved SIP 

Because the area had previously been a 1-hour ozone maintenance area, the state air agency 

verifies that the HOT lane had not also been included in the 1-hour ozone maintenance plan. 

Therefore, there are no backsliding issues that would need to be addressed.17 

17 If the HOT lane had been included in the area’s 1-hour ozone maintenance plan, the state air agency would have 

to ensure that 8-hour ozone anti-backsliding requirements are met, (69 FR 40013) and that equivalent emissions 

reductions are obtained for all pollutants. Refer to Question 2.10 for additional information. 

23
The state air agency also confirms that the 8-hour attainment demonstration’s emissions 

inventory for a typical summer day indicates that the HOT lane was to provide 0.35 tons per day 

of nitrogen oxide (NOx) emissions reductions and 0.2 tons per day of volatile organic compound 

(VOC) emissions reductions in 2009, which is the year modeled in the attainment demonstration. 

Therefore, based upon the requirement of Clean Air Act section 176(c)(8)(A)(i), the substitute 

TCM(s) will need to reduce NOx emissions by at least 0.35 tons per day and VOC emissions by 

0.2 tons per day in 2009. 

Collaborative process to develop the substitute TCM(s)

Based on the requirements of Clean Air Act section 176(c)(8)(A)(iv)(I), staff from the state air 

agency, MPO, state department of transportation, and the local transit provider meet to review 

projects that could be used as the substitute TCM(s). 

Based on their review, the agencies conclude that there are three projects in the MPO’s current 

long range transportation plan and transportation improvement program (TIP) that they would 

consider as viable substitute TCMs. The three projects are: implementation of express bus 

service to the city’s downtown area, implementation of express bus service from the city’s 

downtown area to the airport, and construction of a 1,000-space park-and-ride lot. 

These projects meet the transportation conformity rule’s definition of a TCM (40 CFR 93.101), 

are scheduled to be completed by 2008, and have the potential to provide emissions reductions 

equivalent or greater to the TCM to be removed from the SIP. 

Determination of equivalent emissions reductions 

The state air agency and MPO agree to work together to calculate the emissions reductions 

attributable to each of the three projects that are being considered as substitutes for the delayed 

HOT lane. The state air agency and MPO use the MPO’s transportation modeling tools, the 

latest emission factor model (in this example MOBILE6.2), and the latest available planning 

assumptions to calculate the emissions reductions from the projects that are being considered as 

substitutes. They determine that each of the projects would provide the following emissions 

reductions: 

Project 

NOx Reductions 

(tons per day) 

VOC Reductions 

(tons per day) 

Express bus service to city’s downtown area 0.2 0.1 

Express bus service between the city’s 

downtown area and the airport 0.15 0.1 

1,000-space park-and-ride lot 0.15 0.1 

The state air agency and the MPO agree to present the modeling results to the state department of 

transportation and the local transit provider and recommend substituting the express bus service 

to the city’s downtown area and the 1,000-space park-and-ride lot for the HOT lane. No single 

TCM would provide sufficient emissions reductions to serve as a substitute, but these two 

substitute TCMs together provide NOx and VOC reductions that are equivalent to the original 

24 
HOT lane. The state air agency and the MPO share the results with the EPA regional office, the 

FHWA division office and the FTA regional office. 

Collaborative process for TCM substitution 

The state air agency, MPO, state department of transportation, local transit provider, EPA 

regional office,18 the FHWA division office, and the FTA regional office meet by conference 

call. They discuss the modeling results, verify that the two projects that will serve as substitutes 

are in the area’s transportation plan and TIP, verify that the two projects are to be completed in 

2008, and discuss next steps. 

During the call, all of the agencies agree that: 

• the two projects taken together meet the criteria that the substitute TCM(s) provide 

equivalent emissions reductions, as required by Clean Air Act section 176(c)(8)(A)(i); 

• the two projects will be completed in 2008, which allows them to comply with Clean Air 

Act section 176(c)(8)(A)(ii)(I); 

• because the two projects are included in the area’s transportation plan and TIP, there is 

evidence of adequate personnel and funding and legal authority to implement the two 

projects as required by Clean Air Act section 176(c)(8)(A)(iii); and 

• for the purposes of this substitution the MPO should start a public comment period to 

fulfill the requirement of Clean Air Act section 176(c)(8)(A)(iv)(III).19 

Public notice and opportunity to comment 

In this example, the MPO uses its established processes to provide notice to the public that a 30-

day comment period on the TCM substitution is beginning. The MPO makes all of the relevant 

supporting information for the substitution available on its website. The supporting information 

includes: 

• a description of the HOT lane being removed from the SIP; 

• descriptions of the TCMs that will substitute for the HOT lane; 

• the modeling done to demonstrate equivalent emissions reductions; 

• a brief explanation as to why the substitution is necessary; and 

• a schedule for implementing the substitute TCMs. 

The public notice also informs the public that because the Clean Air Act TCM substitution 

process is being used, EPA will not be conducting a separate public comment period prior to the 

substitute TCMs being incorporated into the SIP; therefore, the public should make all relevant 

comments during the MPO’s comment period. 

The MPO receives several comments during the comment period, one supporting the planned 

substitution, and two others suggesting alternate TCMs to be used as substitutes. The state air 

agency and MPO consider the suggestions and decide that neither of the suggested alternatives 

could be implemented prior to the area’s attainment date and therefore these could not be used as 

18 Inclusion of the EPA regional office in this collaborative process fulfills the requirements of Clean Air Act section 

176(c)(8)(A)(iv)(II), which requires consultation with EPA during the development of substitute TCMs. 

19 The agencies could have also agreed that the state air agency would carry out the public comment period using the 

established process for soliciting public comments on SIP revisions. 

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substitute TCMs. The MPO shares the comments and the responses with the other agencies 

involved in the substitution. 

State air agency, MPO, and EPA regional office concurrence 

Following the close of the public comment period, staff from all of the involved agencies meet 

by conference call. In this example, all agencies agree that the Clean Air Act requirements had 

been met. The state air agency, MPO, and EPA regional office staff all indicate that their 

agencies intend to concur. 

Following this conference call, the MPO policy board adopts a resolution indicating its 

concurrence on the substitution. The MPO distributes the adopted resolution to all of the 

agencies involved in the substitution. The state air agency and EPA Regional Administrator 

send concurrence letters to each other and the MPO with copies to all of the other agencies 

involved in the substitution. These actions by the state air agency, MPO, and EPA regional 

office fulfill the requirement that these agencies concur on the substitution, per Clean Air Act 

section 176(c)(8)(A)(v). 

Adoption of the substitute TCMs 

Immediately following the concurrence of the state air agency, MPO, and EPA regional office, 

the substitute TCMs are considered to be adopted and therefore are incorporated into the 

federally enforceable SIP as indicated in Clean Air Act section 176(c)(8)(B)(i) and (ii). 

Additionally, immediately following the adoption of the substitute TCMs, the delayed HOT lane 

is no longer in effect for SIP and transportation conformity purposes and is removed from the 

approved SIP as indicated in Clean Air Act section 176(c)(8)(E) and (F). Removing the delayed 

TCM from the approved SIP and adding the two substitute TCMs that provide equivalent 

emissions reductions allow the MPO’s upcoming conformity determination to meet the 

transportation conformity rule’s requirements for timely implementation of approved SIP TCMs. 

(40 CFR 93.113) The MPO would include the emissions reductions benefits of the two 

substitute TCMs in the regional emissions analysis for the area, and the MPO would include 

these TCMs in its discussion of timely implementation of TCMs in this and subsequent 

conformity determinations. The substitution also preserves the emissions reductions that were 

relied on in the SIP attainment demonstration. 

Final steps 

Because the substitution is complete in less than six months, the MPO is able to make its 

conformity determination as planned. 

As required by Clean Air Act section 176(c)(8)(B)(iii), within 90 days after the adoption of the 

substitute TCMs the state air agency submits the substitute TCMs and the supporting 

documentation to the EPA regional office so that EPA can keep the list of SIP-approved TCMs 

up to date. 

The state where this example occurs is not yet on the “SIP notebook system;” therefore, the EPA 

regional office publishes a final action notice in the Federal Register to remove the HOT lane 

from the list of SIP-approved TCMs for the nonattainment area and to add the two substitute 

TCMs to the list of SIP-approved TCMs. The Federal Register notice indicates that there is 

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“good cause” under the Administrative Procedure Act to take a final action without additional 

notice and comment rulemaking. The good cause is based on the two elements. First, the 

substitution was made according to the Clean Air Act section 176(c)(8) procedures. Second, the 

public was made aware during the MPO’s comment period that if EPA concurred on the 

substitution, it would not be conducting a public comment period prior to incorporating the 

substitute TCMs into the SIP. 

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APPENDIX D 

 Example of How to Add a TCM to an Approved SIP Using Clean Air Act Section 176(c)(8) 

This appendix provides an example of how a nonattainment or maintenance area could use the 

Clean Air Act section 176(c)(8) TCM substitution process to add a new TCM(s) to the area’s 

approved SIP. 

D.1 Why would a nonattainment or maintenance area want to quickly add a new TCM to 

a SIP? 

For example, a state air quality agency, MPO, and state department of transportation for an area 

that is currently designated as nonattainment for the 1997 8-hour ozone standard decide to 

expeditiously add a particular TCM to the area’s SIP as a way to ensure that the project will 

move forward as currently scheduled and planned. The area is expecting to be designated 

nonattainment for the 2008 8-hour ozone standard and they would like to ensure that this project 

will be completed in time to provide emissions reductions that will help the area attain or 

maintain the 2008 ozone standard. The TCM that they are considering adding to the approved 

SIP is a light rail project connecting two cities and their suburbs. 

D.2 How would the area proceed to add a TCM(s) to the approved SIP? 

Collaborative process to develop the TCM(s) to be added to the approved SIP 

Based on the requirements of Clean Air Act section 176(c)(8)(A)(iv)(I), staff from the state air 

agency, MPO, state department of transportation, and the local transit provider meet to discuss 

the light rail project that they are considering adding to the approved SIP as a TCM. 

During their meeting they verify that the light rail project is included in the area’s transportation 

plan and that preliminary design of the project is being funded in the area’s current TIP. They 

conclude that it is in the best interest of the area to add the TCM to the SIP now to ensure that it 

is completed as currently planned in 2015 and will be in operation in time to provide emissions 

reductions toward attainment or maintenance of the 2008 8-hour ozone standard.20 

The agencies agree to discuss their decision with the EPA regional office, the FHWA division 

office and the FTA regional office. 

Collaborative process for the TCM addition 

The state air agency, MPO, state department of transportation, local transit provider, EPA 

regional office,21 the FHWA division office, and the FTA regional office meet by conference 

20 EPA revised the 8-hour ozone air quality standard in March 2008. EPA intends to designate nonattainment areas 

in 2010. SIPs for these areas will be due in 2013 and it is likely that many of these areas will have attainment dates 

in the range of 2013 to 2019. Therefore, a light rail project that is to begin operation in 2015 would provide 

emissions reductions that would help the area either attain or maintain the 2008 8-hour ozone standard. 21 Inclusion of the EPA regional office in this collaborative process fulfills the requirements of Clean Air Act section 

176(c)(8)(A)(iv)(II), which requires consultation with EPA during the development of additional TCMs. 

29
call. They discuss the decision to add the light rail project to the approved SIP, verify that the 

project is in the area’s transportation plan and TIP, and discuss next steps. 

During the call, all of the agencies agree that: 

• because the project is included in the area’s transportation plan and TIP, there is evidence 

of adequate personnel and funding and legal authority to implement the project as 

required by Clean Air Act section 176(c)(8)(A)(iii); and 

• the state air agency should start a public comment period, to fulfill the requirement of 

Clean Air Act section 176(c)(8)(A)(iv)(III).22 

Public notice and opportunity to comment 

The state air agency uses its established process to provide notice to the public that a 30-day 

comment period on the TCM addition is beginning. The state air agency makes all of the 

relevant supporting information for the addition available on its website. The supporting 

information includes: 

• a description of the light rail project that is to be added to the approved SIP; 

• a brief explanation as to why the addition is being made; 

• an estimate of the emissions reductions expected when the project opens in 2015; and 

• a schedule for implementing the additional TCM. 

The public notice also informs the public that because the Clean Air Act section 176(c)(8) TCM 

addition process is being used, EPA will not be conducting a separate public comment period 

prior to the additional TCM being incorporated into the SIP; therefore, the public should make 

all relevant comments during this comment period. 

The state air agency receives several comments during the comment period, one supporting the 

planned addition, and two others suggesting other TCMs that could be added to the SIP. The 

state air agency and MPO consider the suggestions and decide that none of the other suggested 

TCMs are good candidates to be added to the SIP at this time. The state air agency shares the 

comments and the responses with the other agencies involved in the TCM addition. 

State air agency, MPO, and EPA regional office concurrence 

Following the close of the public comment period, staff from all of the involved agencies meet 

by conference call. In this example, all agencies agree that the Clean Air Act requirements had 

been met. The state air agency, MPO, and EPA regional office staff all indicate that their 

agencies intend to concur. 

Following this conference call, the MPO policy board adopts a resolution indicating its 

concurrence on the addition. They distribute the adopted resolution to all of the agencies 

involved in the addition. The state air agency and EPA Regional Administrator send 

concurrence letters to each other and the MPO with copies to all of the other agencies involved 

in the addition. These actions by the MPO, state air agency and EPA regional office fulfill the 

22 The agencies could have also agreed that the MPO would carry out the public comment period using the 

established process for soliciting public comments on conformity determinations. 

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requirement that these agencies concur on the addition, per Clean Air Act section 

176(c)(8)(A)(v). 

Adoption of the additional TCMs 

Immediately following the concurrence of the state air agency, MPO, and EPA regional office, 

the additional TCM is considered to be adopted and therefore are incorporated into the federally 

enforceable SIP as indicated in Clean Air Act section 176(c)(8)(B)(i) and (ii). At this point the 

MPO would include the emissions reductions benefits of the light rail line in the regional 

emissions analysis for the area and the MPO would include this TCM in its discussion of timely 

implementation of TCMs in subsequent conformity determinations. 

Final steps 

As required by Clean Air Act section 176(c)(8)(B)(iii), within 90 days after the adoption of the 

additional TCMs the state air agency submits the additional TCM and the supporting 

documentation to the EPA regional office so that EPA can keep the list of SIP-approved TCMs 

up to date. 

The state where this example occurs is not yet on the “SIP notebook system;” therefore, the EPA 

regional office publishes a final action notice in the Federal Register to add the light rail project 

to the list of SIP-approved TCMs. The Federal Register notice indicates that there is “good 

cause” under the Administrative Procedure Act to take a final action without additional notice 

and comment rulemaking. The good cause is based on the two elements. First, the addition was 

made according to the Clean Air Act section 176(c)(8) procedures. Second, the public was made 

aware during the state air agency and MPO comment period on the addition that if EPA 

concurred on the addition, it would not be conducting a public comment period prior to 

incorporating the additional TCMs into the SIP. 

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