Models & Methodologies
Many different software programs and other modeling techniques are utilized conducting air quality analyses. For instance, various EPA models can be used to predict emissions of different pollutants from on-road and nonroad sources, to calculate delays and queues that occur at signalized intersections, and to provide estimates on how commuter benefits can impact vehicle emissions, as well as fuel use and costs. In addition, FHWA has developed some tools based on these models to make emission inventory calculations in rural or small urban areas and to provide user-friendly interfaces to some of the models
- AERMOD - A steady-state plume model that incorporates air dispersion based on planetary boundary layer turbulence structure and scaling concepts, including treatment of both surface and elevated sources, and both simple and complex terrain.
- COMMUTER Programs - EPA Guidance on Emissions and Emission Reductions from Commuter Programs
- Easy Mobile Inventory Tool (EMIT) - Information about the EMIT model from the FHWA Resource Center
- EPA's MOBILE6 Vehicle Emission Modeling Software - EPA website for its MOBILE6 Vehicle Emission Modeling Software, as well as related presentations and training resources
- EPA's MOVES (Motor Vehicle Emission Simulator) Website - EPA website for its MOVES software, as well as related presentations and training resources
- National Mobile Inventory Model (NMIM) - EPA's website for its NMIM software
- User Friendly Version of CAL3QHC - The FHWA Resource Center is designing a new, easy-to-use interface for two air quality models: EPA's California Line Source Dispersion Model (CALINE3) for freeways and the CAL3QHC model for signalized intersections. With the new interface, the models will run on the Microsoft Windows® operating system and will include interactive graphical forms for entering data.
- Diesel Retrofits: Quantifying and Using Their Emission Benefits in SIPs and Conformity - Guidance for State and Local Air and Transportation Agencies (EPA, February 2014) - Guidance on quantifying and using emission reductions from on-road and nonroad diesel vehicles, engines, and equipment that have been retrofitted with emission reduction technology. This guidance supersedes EPA's June 2006 guidance under the same name.
- Transportation Conformity Guidance for Quantitative Hot-spot Analyses in PM2.5 and PM10 Nonattainment and Maintenance Areas (EPA, November 2013) - Guidance for modeling the local air quality impacts of certain transportation projects on the PM2.5 and PM10 national ambient air quality standards (NAAQS). This guidance is to be used by state and local agencies to conduct quantitative PM "hot-spot analyses" for new highway and transit projects that involve significant diesel emissions. Update of November 2013: This guidance was originally released in December 2010, and Sections 5, 7.6, and 9.4 have been updated to reflect EMFAC2011 and EPA's 2012 PM NAAQS final rule. The November 2013 guidance supersedes the December 2010 guidance.
- Federal Register Notice of Availability: Official Release of EMFAC2011 Motor Vehicle Emission Factor Model for Use in the State of California (March 2013) - In this notice, EPA is approving and announcing that EMFAC2011 is available to use in statewide California SIP development and for regional emissions analyses and CO, PM 10 and PM 2.5 hot-spot analyses for transportation conformity. EMFAC2011 must be used for all new regional emissions analyses and CO, PM 10 and PM 2.5 hot-spot analyses that are started on or after September 6, 2013.
- Federal Register Notice of Availability: Official Release of the MOVES2010a and EMFAC2007 Motor Vehicle Emissions Models for Transportation Conformity Hot-Spot Analyses and Availability of Modeling Guidance (December 2010) – This notice approves MOVES2010a for PM and CO hot-spot analyses (and EMFAC2007 for PM hot-spot analyses in California) with a 2-year conformity grace period. EPA also announced the availability of its final PM hot-spot guidance and CO project-level MOVES guidance.
- Using MOVES in Project-Level Carbon Monoxide Analyses (EPA, December 2010) - This guidance describes how to use the MOVES emissions model to estimate CO emissions from transportation projects, including roadway intersections, highways, transit projects, parking lots and intermodal terminals.
- Official Release of EMFAC2007 Motor Vehicle Emission Factor Model for Use in the State of California (January 2008) - Federal Register notice announcing the availability of the latest version of the California EMFAC model for use in state implementation plan (SIP) development in California
- A Sampling of Emissions Analysis Techniques for Transportation Control Measures. (FHWA, November, 2000 ) (Also in PDF - 2.9 MB ) - This report describes modeling tools and other methods that can be used to assess the emissions benefits of transportation control measures and other projects in applying for CMAQ funds. The report is primarily intended for state or local air quality/transportation program analysts, but also others interested in estimating the emissions benefits of CMAQ projects.
- Off-Model Air Quality Analysis: A Compendium of Practice. (FHWA Southern Resource Center, August 1999) - This compendium offers a look into several methodologies, utilized in the FHWA's Southern Resource Center geographic area, that provide for the evaluation of possible emission reductions. These methodologies are not all encompassing but should offer insight into off-model practice.