The Environmental Protection Agency (EPA) uses software to enforce the Clean Air Act, which restricts certain pollutants found in urban areas with heavy traffic. Cities that exceed these standards are said to be in “nonattainment.” Using software called MOBILE6, agencies can estimate future vehicle emissions, and individual states can use data to create these implementation plans to bring their nonattainment areas into compliance.
The Texas Transportation Institute (TTI) helps support the Texas State Implementation Plan by using MOBILE6 to estimate emissions. “Once an area is in noncompliance, it must demonstrate how it will conform to future air quality standards,” explains Dennis Perkinson, manager of TTI‘s Transportation Modeling Program. “Our work provides these crews with the information to do so.”
Though MOBILE6 has been a good tool, the EPA is planning to change the software it uses to estimate emissions to Motor Vehicle Emissions Simulator (MOVES). While both programs estimate essentially the same pollutants, MOVES allows researchers to slice up those estimates in more sophisticated ways.
“With MOBILE6, we easily knew the difference between an 18-wheeler and a Volkswagon,” explains Perkinson. “Now, we not only know that difference, but also what those two vehicles are actually being used for — short- or long-haul trucking, for example, in the case of the semitruck.”
TTI‘s Transportation Modeling Program is on the leading edge of this conversion effort. TTI researchers are currently preparing to develop application protocols and test MOVES in a Texas urban setting on behalf of the Texas Department of Transportation (TxDOT) and Texas Commission on Environmental Quality, respectively. Their research will demonstrate how MOVES compares to MOBILE6 in real-world conditions.
“The challenge is to make this conversion with no break in service,” says Perkinson. “It’s like when a city changes over its power grid from one system to another…if the lights go out, they did it wrong.”
The transition to MOVES needs to be seamless to avoid interrupting information flow for sponsoring agencies that depend on that data. That information is instrumental to an agency’s ability to retain federal funding, which can be put at risk if the agency is unable to demonstrate conformity with EPA standards.
“Thanks to TTI, Texas will hit the ground running as MOVES is implemented nationwide,” says Paul Tiley, technical working group coordinator of TxDOT‘s Transportation Planning and Programming Division. “More accurate estimates provided by this software will help our cities demonstrate compliance with the EPA…and that will help us all breathe a little easier.”