This paper defines and evaluates a pilot implementation of a recently developed approach to realtime,adaptive traffic signal control. The pilot system, which is called SURTRAC (Scalable UrbanTraffic Control), integrates concepts from traffic control theory with recent work in the field ofmulti-agent planning and has several important distinguishing characteristics. First, to promotescalability and reliability, SURTRAC operates in a totally decentralized manner; each intersectionindependently and asynchronously allocates its green time, based on current incoming vehicleflows. Second, SURTRAC aims at managing urban (grid-like) road networks with multiple (competing)traffic flows; network-level coordination is accomplished by communicating projected outflowsto downstream neighbors, which gives these intersections a more informed basis for locallybalancing competing inflows while simultaneously promoting establishment of larger "green corridors".Third, SURTRAC truly operates in real-time; each intersection recomputes its allocationplan and re-communicates projected outflows as frequently as once per second in rolling horizonfashion, enabling both effective operation in tightly spaced signal networks and responsiveness tosudden changes in traffic conditions. After describing our basic approach to adaptive traffic signalcontrol and the pilot implementation of SURTRAC, we present the results of a field test conductedon a nine-intersection road network in the East Liberty section of Pittsburgh, Pennsylvania. In thispilot test, SURTRAC is seen to achieve major reductions in travel times and vehicle emissions overpre-existing signal control.
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