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Guidance to MPOs and States for Estimating the Emission Reductions, Cost and Cost-Effectiveness of Co-Pollutant Control Strategies for On-road Vehicles


This problem statement was developed in response to the key research needs identified by the Regional Air Quality Subcommittee of the TRB ADC20 (Transportation-Air Quality) full committee, during the TRB 2015 meeting.

State departments of transportation (DOTs) need a set of analysis practices and tools to estimate emissions for criteria pollutants, greenhouse gases (e.g., nitrous oxide and methane), and mobile source air toxics based on the Environmental Protection Agency (EPA) Motor Vehicle Emission Simulator (MOVES) model, where applicable.

A number of studies have provided pieces of the information needed by State DOTs and regional planning organizations, but stakeholders still identify a need for more consistent methods and tools for analysis. The results of past studies are either incomplete or are outdated.

Although the projects not expected to produce new analysis methods for control measure assessment, it will provide a set of tools and associated instructions for using the tools to assess selected options within a category of emissions control strategy. This project will also include innovative mitigation measures that have only been piloted or explored in recent years.

One of the key contributions of this study should be to provide analysts with a uniform set of assumptions to be used in strategy assessments, such as the discount rate, and the anticipated project lifetime. These methods should be based on standard practice for Congestion Mitigation and Air Quality (CMAQ) evaluations and federal agency guidelines for cost and economic analyses. The product of this research project shall also provide suggested weighting system for assessing the cost effectiveness of strategies that reduce more than one criteria pollutant.

The urgency of this research results from the 2014 EPA proposal to revise the ozone National Ambient Air Quality Standards (NAAQS) to a level within the range of 65 to 70 ppb (from 75 ppb) that will cause States to pursue methods of emission reduction strategies. New PM-2.5 nonattainment areas will also benefit from this project. Furthermore, Federal Highway Administration (FHWA) is establishing performance measures that will require State DOTs to meet on-road vehicle emission reduction goals. These goals will need to be quantified using a defined systematic approach to estimate the emission reductions of various strategies and that provides greater consistency and accountability then current analysis methods.


To provide agencies with air quality or climate planning responsibilities with the means to estimate multi-pollutant benefits of on-road vehicle control strategies of interest.

Related Research:

There have been several studies undertaken investigating multi-pollutant control benefits. Most of these have been non-sector (mobile, stationary, area) specific. This study would be specific to the transportation community. It should be noted that one study (see FHWA, 2006, below) did investigate several strategies and their impact on the transportation, but this study did not include hazardous air pollutants or GHGs.

(1) Air Quality Management in the United States, National Research Council of the NAS report, 2004

(2) Multi-Pollutant Emission Benefits of Transportation Strategies, FHWA, 2006

(3) Improving Emission Inventories for Effective Air Quality Management Across North America, NARSTO-05-01, 2009

(4) Multi-Pollutant Air Quality Management, JAWMA, 2010

(5) A Risk-based Assessment And Management Framework for Multipollutant Air Quality, AWMA Proceedings, Frey, et al, 2009

(6) Protecting Human Health From Air Pollution Shifting From a Single-pollutant to a Multipollutant Approach, Epidemiology, 2010

(7) Vision for Clean Air: A Framework for Air Quality and Climate Planning, California Air Resources Board, 2012

(8) Evaluate the Interactions between Transportation-Related Particulate Matter, Ozone, Air Toxics, Climate Change, and Other Air-Pollutant Control Strategies, NCHRP 25-25, Task 59 report by CS and ERG, July 19, 2010.

(9) Reference Sourcebook for Reducing Greenhouse Gas Emissions from Transportation Sources, FHWA Project DTFH61-09-F-00117, by RAND Corporation and RSG, Inc., February 2012.


When EPA takes final action at the end of 2015 to revise the ozone NAAQS, the level of the primary and secondary standards will be in the range of 65 to 70 ppb. This tightening of the NAAQS will set in motion a timetable for nonattainment areas to develop and submit new or revised state implementation plans to EPA. States need control measure guidance to be available early in this process. New PM-2.5 nonattainment areas will also benefit from this project. In addition, FHWA is establishing performance measures that will require State DOTs to quantify emission reductions from vehicle programs and/or projects using an approach that will insure greater consistency.

Sponsoring Committee:AMS10, Air Quality and Greenhouse Gas Mitigation
Source Info:Kevin Black
Air Quality Specialist
FHWA Resource Center
10 South Howard Street Suite 4000
Baltimore, MD 21201
Ph: (410) 962-2177

Charles Baber
Baltimore Metropolitan Council
1500 Whetstone Way, Suite 300
Baltimore, MD 21230
410-732-0500, x1056

Christopher Voigt
VDOT, Senior Environmental Engineer
Chair, Project Level Analysis Air Quality Subcommittee,
TRB Transportation & Air Quality Committee (ADC20)
Ph: 804-371-6764
email: Christopher.Voigt@VDOT.Virginia.gov
Date Posted:12/18/2015
Date Modified:01/05/2016
Index Terms:Air quality management, Metropolitan planning organizations, Exhaust gases, Pollutants, State departments of transportation, Air pollution, Particulates, Ozone, Motor Vehicle Emission Simulator (MOVES), Congestion Mitigation and Air Quality Improvement Program,
Cosponsoring Committees: 
Transportation (General)

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