[Code of Federal Regulations]
[Title 40, Volume 18]
[Revised as of July 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR93.122]
[Page 565-568]
TITLE 40--PROTECTION OF ENVIRONMENT
CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
PART 93--DETERMINING CONFORMITY OF FEDERAL ACTIONS TO STATE OR FEDERAL
IMPLEMENTATION PLANS--Table of Contents
Subpart A--Conformity to State or Federal Implementation Plans of
Transportation Plans, Programs, and Projects Developed, Funded or
Approved Under Title 23 U.S.C. or the Federal Transit Laws
Sec. 93.122 Procedures for determining regional transportation-related
emissions.
(a) General requirements. (1) The regional emissions analysis
required by Secs. 93.118 and 93.119 for the transportation plan, TIP, or
project not from a conforming plan and TIP must include all regionally
significant projects expected in the nonattainment or maintenance area.
The analysis shall include FHWA/FTA projects proposed in the
transportation plan and TIP and all other regionally significant
projects
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which are disclosed to the MPO as required by Sec. 93.105. Projects
which are not regionally significant are not required to be explicitly
modeled, but vehicle miles traveled (VMT) from such projects must be
estimated in accordance with reasonable professional practice. The
effects of TCMs and similar projects that are not regionally significant
may also be estimated in accordance with reasonable professional
practice.
(2) The emissions analysis may not include for emissions reduction
credit any TCMs or other measures in the applicable implementation plan
which have been delayed beyond the scheduled date(s) until such time as
their implementation has been assured. If the measure has been partially
implemented and it can be demonstrated that it is providing quantifiable
emission reduction benefits, the emissions analysis may include that
emissions reduction credit.
(3) Emissions reduction credit from projects, programs, or
activities which require a regulatory action in order to be implemented
may not be included in the emissions analysis unless:
(i) The regulatory action is already adopted by the enforcing
jurisdiction;
(ii) The project, program, or activity is included in the applicable
implementation plan;
(iii) The control strategy implementation plan submission or
maintenance plan submission that establishes the motor vehicle emissions
budget(s) for the purposes of Sec. 93.118 contains a written commitment
to the project, program, or activity by the agency with authority to
implement it; or
(iv) EPA has approved an opt-in to a Federally enforced program, EPA
has promulgated the program (if the control program is a Federal
responsibility, such as vehicle tailpipe standards), or the Clean Air
Act requires the program without need for individual State action and
without any discretionary authority for EPA to set its stringency, delay
its effective date, or not implement the program.
(4) Emissions reduction credit from control measures that are not
included in the transportation plan and TIP and that do not require a
regulatory action in order to be implemented may not be included in the
emissions analysis unless the conformity determination includes written
commitments to implementation from the appropriate entities.
(i) Persons or entities voluntarily committing to control measures
must comply with the obligations of such commitments.
(ii) The conformity implementation plan revision required in
Sec. 51.390 of this chapter must provide that written commitments to
control measures that are not included in the transportation plan and
TIP must be obtained prior to a conformity determination and that such
commitments must be fulfilled.
(5) A regional emissions analysis for the purpose of satisfying the
requirements of Sec. 93.119 must make the same assumptions in both the
``Baseline'' and ``Action'' scenarios regarding control measures that
are external to the transportation system itself, such as vehicle
tailpipe or evaporative emission standards, limits on gasoline
volatility, vehicle inspection and maintenance programs, and oxygenated
or reformulated gasoline or diesel fuel.
(6) The ambient temperatures used for the regional emissions
analysis shall be consistent with those used to establish the emissions
budget in the applicable implementation plan. All other factors, for
example the fraction of travel in a hot stabilized engine mode, must be
consistent with the applicable implementation plan, unless modified
after interagency consultation according to Sec. 93.105(c)(1)(i) to
incorporate additional or more geographically specific information or
represent a logically estimated trend in such factors beyond the period
considered in the applicable implementation plan.
(7) Reasonable methods shall be used to estimate nonattainment or
maintenance area VMT on off-network roadways within the urban
transportation planning area, and on roadways outside the urban
transportation planning area.
(b) Regional emissions analysis in serious, severe, and extreme
ozone nonattainment areas and serious CO nonattainment areas must meet
the requirements of paragraphs (b) (1)
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through (3) of this section if their metropolitan planning area contains
an urbanized area population over 200,000.
(1) By January 1, 1997, estimates of regional transportation-related
emissions used to support conformity determinations must be made at a
minimum using network-based travel models according to procedures and
methods that are available and in practice and supported by current and
available documentation. These procedures, methods, and practices are
available from DOT and will be updated periodically. Agencies must
discuss these modeling procedures and practices through the interagency
consultation process, as required by Sec. 93.105(c)(1)(i). Network-based
travel models must at a minimum satisfy the following requirements:
(i) Network-based travel models must be validated against observed
counts (peak and off-peak, if possible) for a base year that is not more
than 10 years prior to the date of the conformity determination. Model
forecasts must be analyzed for reasonableness and compared to historical
trends and other factors, and the results must be documented;
(ii) Land use, population, employment, and other network-based
travel model assumptions must be documented and based on the best
available information;
(iii) Scenarios of land development and use must be consistent with
the future transportation system alternatives for which emissions are
being estimated. The distribution of employment and residences for
different transportation options must be reasonable;
(iv) A capacity-sensitive assignment methodology must be used, and
emissions estimates must be based on a methodology which differentiates
between peak and off-peak link volumes and speeds and uses speeds based
on final assigned volumes;
(v) Zone-to-zone travel impedances used to distribute trips between
origin and destination pairs must be in reasonable agreement with the
travel times that are estimated from final assigned traffic volumes.
Where use of transit currently is anticipated to be a significant factor
in satisfying transportation demand, these times should also be used for
modeling mode splits; and
(vi) Network-based travel models must be reasonably sensitive to
changes in the time(s), cost(s), and other factors affecting travel
choices.
(2) Reasonable methods in accordance with good practice must be used
to estimate traffic speeds and delays in a manner that is sensitive to
the estimated volume of travel on each roadway segment represented in
the network-based travel model.
(3) Highway Performance Monitoring System (HPMS) estimates of
vehicle miles traveled (VMT) shall be considered the primary measure of
VMT within the portion of the nonattainment or maintenance area and for
the functional classes of roadways included in HPMS, for urban areas
which are sampled on a separate urban area basis. For areas with
network-based travel models, a factor (or factors) may be developed to
reconcile and calibrate the network-based travel model estimates of VMT
in the base year of its validation to the HPMS estimates for the same
period. These factors may then be applied to model estimates of future
VMT. In this factoring process, consideration will be given to
differences between HPMS and network-based travel models, such as
differences in the facility coverage of the HPMS and the modeled network
description. Locally developed count- based programs and other
departures from these procedures are permitted subject to the
interagency consultation procedures of Sec. 93.105(c)(1)(i).
(c) In all areas not otherwise subject to paragraph (b) of this
section, regional emissions analyses must use those procedures described
in paragraph (b) of this section if the use of those procedures has been
the previous practice of the MPO. Otherwise, areas not subject to
paragraph (b) of this section may estimate regional emissions using any
appropriate methods that account for VMT growth by, for example,
extrapolating historical VMT or projecting future VMT by considering
growth in population and historical growth trends for VMT per person.
[[Page 568]]
These methods must also consider future economic activity, transit
alternatives, and transportation system policies.
(d) PM10 from construction-related fugitive dust. (1) For
areas in which the implementation plan does not identify construction-
related fugitive PM10 as a contributor to the nonattainment
problem, the fugitive PM10 emissions associated with highway
and transit project construction are not required to be considered in
the regional emissions analysis.
(2) In PM10 nonattainment and maintenance areas with
implementation plans which identify construction-related fugitive
PM10 as a contributor to the nonattainment problem, the
regional PM10 emissions analysis shall consider construction-
related fugitive PM10 and shall account for the level of
construction activity, the fugitive PM10 control measures in
the applicable implementation plan, and the dust-producing capacity of
the proposed activities.
(e) Reliance on previous regional emissions analysis. (1) The TIP
may be demonstrated to satisfy the requirements of Secs. 93.118 (``Motor
vehicle emissions budget'') or 93.119 (``Emission reductions in areas
without motor vehicle emissions budgets'') without new regional
emissions analysis if the regional emissions analysis already performed
for the plan also applies to the TIP. This requires a demonstration
that:
(i) The TIP contains all projects which must be started in the TIP's
timeframe in order to achieve the highway and transit system envisioned
by the transportation plan;
(ii) All TIP projects which are regionally significant are included
in the transportation plan with design concept and scope adequate to
determine their contribution to the transportation plan's regional
emissions at the time of the transportation plan's conformity
determination; and
(iii) The design concept and scope of each regionally significant
project in the TIP is not significantly different from that described in
the transportation plan.
(2) A project which is not from a conforming transportation plan and
a conforming TIP may be demonstrated to satisfy the requirements of
Sec. 93.118 or Sec. 93.119 without additional regional emissions
analysis if allocating funds to the project will not delay the
implementation of projects in the transportation plan or TIP which are
necessary to achieve the highway and transit system envisioned by the
transportation plan, and if the project is either:
(i) Not regionally significant; or
(ii) Included in the conforming transportation plan (even if it is
not specifically included in the latest conforming TIP) with design
concept and scope adequate to determine its contribution to the
transportation plan's regional emissions at the time of the
transportation plan's conformity determination, and the design concept
and scope of the project is not significantly different from that
described in the transportation plan.