Examining Perimeter Gating Control of Urban Traffic Networks with Locally Adaptive Traffic Signals

Traditionally, urban traffic is controlled by traffic lights. Recent findings of the Macroscopic or Network Fundamental Diagram (MFD or NFD) have led to the development of novel traffic control strategies that can be applied at a network-wide level. One pertinent example is perimeter flow control (also known as gating or metering), which limits the rate at which vehicles are allowed to enter an urban region. This paper studies to which extent a combination of adaptive traffic control and gating improves the traffic flow. To this end, combinations of gating and traffic signal timing tested implemented in a microsimulation. It is found that gating is much more effective than adaptive signal timing for high traffic loads. Adaptive signal timing can improve the network performance by increasing the maximum flow and increasing the critical accumulation, i.e. the number of vehicles inside a protected network for which the performance is maximised. The latter helps to reduce queuing outside the protected network.