Along with frustrating drivers and wasting fuel sitting in traffic during rush hour also adds unnecessary greenhouse gas emissions to the atmosphere.
A study by researchers at the Massachusetts Institute of Technology (MIT) could lead to better ways of programming a city’s stoplights to reduce delays, improve efficiency and reduce idling and emissions.
The researchers have come up with a method of combining vehicle-level data with less precise – but more comprehensive – city-level data on traffic patterns to produce better information than current systems provide.
Algorithms were developed that allow major transportation agencies to use high-resolution models of traffic to solve optimization problems, explains Carolina Osorio, an MIT assistant professor of civil and environmental engineering. “Typically, such timing determinations are set to optimize travel times along selected major arteries, but are not sophisticated enough to take into account the complex interactions among all streets in a city.
“In addition, current models do not assess the mix of vehicles on the road at a given time, so they can’t predict how changes in traffic flow may affect overall fuel use and emissions.”
ENOUGH SPECIFICS
While existing programs can simulate both city-scale and driver-scale traffic behavior, integrating the two has been a problem. The MIT researcher found ways of reducing the amount of detail sufficiently to make the computations practical, while still retaining enough specifics to make useful predictions and recommendations.
“With such complicated models, we had been lacking algorithms to show how to use the models to decide how to change patterns of traffic lights,” Osorio says.
Along with optimizing travel times, the new model incorporates specific information about fuel consumption and emissions for vehicles from motorcycles to buses, reflecting the actual mix seen in the city’s traffic.
“The data needs to be very detailed, not just about the vehicle fleet in general, but the fleet at a given time,” she points out. “Based on that detailed information, we can come up with traffic plans that produce greater efficiency at the city scale in a way that’s practical for city agencies to use.”
She says government agencies are now being asked, whenever they propose changes, to estimate what impact that will have environmentally. “Currently, such evaluations need to be made after the fact, through actual measurements. But with these new software tools, we can put the environmental factors in the loop in designing the plan.”
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