An official website of the United States government.

We've made some changes to If the information you are looking for is not here, you may be able to find it on the EPA Web Archive or the January 19, 2017 Web Snapshot.

Community-LINE Source Model (C-LINE) to estimate roadway emissions

What is the Community-LINE Source Model (C-LINE)?

C-LINE is a web-based model that estimates emissions and dispersion of toxic air pollutants for roadways in the U.S. This reduced-form air quality model can examine what-if scenarios for changes in emissions, such as traffic volume, fleet mix and vehicle speed. C-LINE accesses inputs, performs atmospheric dispersion calculations, visualizes results, provides options to manipulate input variables, and performs basic data analysis to present model results in an interpretable manner.

What are the benefits of using C-LINE?

C-LINE can identify potentially at-risk populations located near roadways and effects that changes in traffic activity may have on those populations. Currently, C-LINE is capable of modeling any region of the U.S. and can be applied to a number of community-scale applications such as assessing air quality by schools located near busy highways.

Who should use C-LINE?

C-LINE is intended to support local communities and planners to get an initial assessment of near-source air quality impacts of transportation-related sources using national-scale input databases, and reduced-form modeling approaches.

How does C-LINE work?

C-LINE computes air quality concentrations of primary mobile source pollutants using analytical version of R-LINE dispersion model. Specific emissions for each road link are calculated by combining national database information on traffic volume and fleet mix with emissions factors from EPA’s MOtor Vehicle Emission Simulator (MOVES) modeling system. Users can modify emissions for each road link by changing traffic composition, speed and/or volume. C-LINE is currently capable of modeling any region of the United States

Download Now:

C-LINE 2.0 can be downloaded from the Community Modeling and Analysis System (CMAS).

EPA instituted the CMAS website in 2001 to provide community air quality modeling support, sharing of ideas and techniques through communication, and to encourage the growth of the community. It is currently operated under contract by the University of North Carolina at Chapel Hill’s Institute for the Environment.


Related Links:

Technical Contacts: