Green Routing Can Cut Car Emissions With Minimal Slowdown

BUFFALO, New York, December 22, 2011 (ENS) – The path of least emissions may not always be the fastest way to drive somewhere, but drivers can reduce their tailpipe emissions without significantly slowing travel time, finds new research from the State University of New York at Buffalo.

In detailed computer simulations of traffic in Upstate New York’s Buffalo Niagara region, researchers Adel Sadek and Liya Guo found that green routing could reduce overall carbon monoxide emissions by 27 percent, while increasing the length of trips by an average of just 11 percent. Simple changes yielded great gains.

Routing cars along surface streets instead of freeways helped to limit fuel consumption.

Intelligently targeting travelers was another strategy that worked: Rerouting just one fifth of drivers – those who would benefit most from a new path – reduced regional emissions by about 20 percent.

Rush hour in Chicago (Photo by Seth Oliver)

Sadek, a transportation systems expert, says one reason green routing is appealing is because consumers and transportation agencies could start using the strategy today.

“We’re not talking about replacing all vehicles with hybrid cars or transforming to a hydrogen-fuel economy – that would take time to implement,” said Sadek, an associate professor of civil, structural and environmental engineering. “But this idea, green routing, we could implement it now.”

In the near future, GPS navigation systems and online maps could play an important role in promoting green routing. These systems and mapping programs could use transportation research to give drivers the choice of environmentally friendly routes or the shortest route.

Sadek and Guo, a PhD candidate, presented their research on green routing at the 18th World Congress on Intelligent Transportation Systems in October.

In their study, the researchers tied together two computer models.

The Motor Vehicle Emission Simulator (MOVES), created by the U.S. Environmental Protection Agency, estimates emissions.

The Transportation Analysis and Simulation System (TRANSIMS) simulates traffic in great detail, taking into account the location and pattern of signals; the grade of the road; and the trips people take at different times of day.

After feeding Buffalo-specific data into TRANSIMS, Sadek and Guo ran simulations that rerouted travelers in new ways each time.

The researchers ran the computer models repeatedly, until they reached a “green-user equilibrium,” a traffic pattern where all drivers are traveling along optimal routes.

With the system in equilibrium, moving a commuter from one path to another would increase a user’s overall emissions by creating more congestion or some other problem.

The simulations are part of a broader study Sadek is doing to evaluate the environmental benefits of green routing in the region. His project is one of seven the U.S. Department of Transportation has funded that use intelligent transportation systems to reduce the environmental impact of mobility.

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