Traffic State Estimation Using GPS/SCATS Data

Developing Advanced Traffic Information System (ATIS) has become the key method to improve efficiency of traffic networks and decrease traffic accident. Real-time and accurately analysing urban traffic flow and then acquiring dynamic traffic state of road networks is the key techonology of Intelligent Transportation System.Real-time estimation of road-network traffic status is determined by the traffic information used. Different traffic information determines method and accuracy of traffic estimation and prediction. Currently, the researches, which are based on magnetic detect loop, detect video data, infra detect data, electronic tag, require so much on the city hardware that in many cities there are not sufficient data for analysis.However, probe ehicles equipped with GPS receivers afford to transmit their real-time location and velocity information periodically to the transportation management center. Therefore, with a higher accuracy and a broader spatial penetration, the probe vehicle approach prevails.Therefore, after a lot of international related research, an Adaptive selection of probe vehicle Sample Sizes Model is developed to calculate the minimum sample size. Our innovations are as follows.(1) Proposed an Adaptive selectin Model of probe vehicle Sample Size. (AMSS) Meantime, Road style, road segment length, numbers of lane and segment, layout of intersection, state information and capability of communication of probe vehicles are taken into account in AMSS.(2) Developed an Adaptive Space-Time Curve Fitting Model based on GPS probe vehicles.which can calcute the average speed of individual directional road segment, thus can estimate traffic state of urban road networks. Field test and application based on inner loop road network at in Shanghai, present the availability and validity of this method, can reveal the real state of urban road networks, with a broader spatial penetration.(3) Researched dynamic estimation of traffic state based on SCATS magnetic detect loop. We analysed data character gathered from SCATS magnetic detect loop. In order to estimate average speed of road segment, we modeled with SCATS data according to classical Traffic-Wave Theory. Field test and application present it can estimate at a higher precision. However, the limited data resulted in its unpopular...