MPO Policy and Procedures Manual - Indianapolis Metropolitan ...

• Reduction of motor vehicle travel: Reducing the total number of vehicle trips, either by
eliminating the need for trips or by encouraging nonmotorized travel modes like biking
and walking, is the best single policy outcome. Closely following this is converting
vehicle trips to transit trips; individual transit vehicles may have higher emissions than
individual motor vehicles, but emissions on a per-person basis are cut drastically.
• Effects of vehicle speed: Since the emission rates of many pollutants vary by speed,
judicious roadway improvements can have a beneficial impact on air quality, but the
impact of improved accessibility on land use patterns and its subsequent effect on
increased trip-making, while not as well-understood as we would like, cannot be ignored.
Also, excessive speeds have emissions rates comparable to if not exceeding those of
low speeds; the “sweet spot” for speed from an emissions perspective appears to be
around 45 mph.
The general process for determining air quality conformity is initiated with the generation of
travel forecasts (in particular, vehicle miles of travel) for the nonattainment area(s). The
subsequent application of per-vehicle emissions rates (as estimated by the latest-generation air
quality model promulgated by the US EPA) are used to derive regional emissions forecasts. The
emissions forecasts for target years are compared to state implementation plan (SIP) mobile
source budgets (if available) or some other interim methodology, in accordance with FHWA and
EPA regulations, to ensure that the emissions forecasts do not exceed allowable levels. The
SIP mobile source budget comes from IDEM with US EPA approval.
Regionally Significant and Exempt Projects
Projects affected by air quality conformity include non-exempt and regionally significant projects.
Non-Exempt projects are defined by Title 40, Chapter 1, Part 93, Subpart A, Sections 93.126 –
93.129. Regionally Significant projects are defined in the same Title and Part: A Regionally
Significant project is a transportation project (other than an exempt project) that is on a facility
which serves regional transportation needs (such as access to and from the area outside of the
region, major activity centers in the region, major planned developments such as new retail
malls, sports complexes, etc., or transportation terminals as well as most transportation
terminals themselves) and would normally be included in the modeling of a metropolitan area’s
transportation network, including at a minimum all principal arterial highways and all fixed
guideway transit facilities that offer an alternative to regional highway travel.
From 40 CFR Ch 1, Section 93.126 Exempt projects may proceed toward implementation even
in the absence of a conforming transportation plan and TIP. A particular action of the type listed
is not exempt if the MPO in consultation with other agencies concur that it has potentially
adverse emissions impacts for any reason. States and MPOs must ensure that exempt projects
do not interfere with TCM implementation.
Exempt Project List
Safety
• Railroad/highway crossing.
• Projects that correct, improve, or eliminate a hazardous location or feature.
• Safer non-Federal-aid system roads.
• Shoulder improvements.
• Increasing sight distance.
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