Study On Optimum Method For Urban Traffic Detector Layout

Intelligent Transportation Systems (ITS) have been developing rapidly in China, their operations are based on realtime traffic information on urban roads. Traffic data collecting from detectors reflect the traffic states of that time, which depends on the spatial layout and position of traffic detectors. How to lay traffic detectors reasonably in urban area has being considered in many cities of china. There are lots of sections of urban roads, and it is difficult to lay detectors on almost every section due to cost. So it is important to establish traffic data collection system to collect the traffic data with an optimal detector layout.In this paper, several existing methods of traffic detector layout are introduced and their characteristics and applicabilities are discussed in detail. In order to figure out the average travel time of vehicles on the main roads or expressways, layout of vehicle license plate automatic recognition systems on the main roads or expressways based on actual travel time investigation, is introduced. Next, fixed traffic detector layout based on digraph theory is proposed to estimate the traffic flow of any urban road section. Now, if the calculated number of detectors is smaller than the intending number based on investment, then stop and the optimal detector layout is gained; otherwise, select a coverage area of roads that traffic flows on them are correlative, conduct the analysis of comparability and decrease some detecotors, if the gross number is still larger than the intending number, select another coverage area of roads, conduct the same analysis until the appropriate number of detectors ia achieved. Finally, an example about traffic detector layout using VISSIM3.60 is given to demonstrate the validity and feasibility of the integrated method proposed.