Simulation of road traffic flow in Hangzhou

Abstract: Is it possible to increase traffic flows and decrease stand stills in rush hour traffic by tweaking existing traffic light signals? A vehicle’s engine running on idle is not useful in physical terms and emits unnecessary exhausts. By investigating and observing signal phase times on site in Hangzhou, China, an effort was made to find out if it was possible to get better flow and thus lower emissions by changing the traffic signal programs. The Simulation of Urban MObility suite developed by the German Aerospace center, DLR, was used to simulate traffic. Three scenarios were simulated. Scenario one tried to find better and smoother flow by reducing the duration of the traffic signals’ phase times. Scenario two allowed both extended and reduced signal phases. Scenario three was based on already existing signal phase times. The findings will show that it is possible to obtain increased throughput of vehicles if some green signal phases and thus cycle times are shortened. This translates as shorter time spent in congested traffic, which results in lower emissions per vehicle.