In order to alleviate traffic jams

enhance road capacity

reduce traffic accidents

lower energy consumption and lessen environmental pollution

it is helpful to build an Intelligent Transportation System（ITS） based on a Wireless Sensor Network（WSN） and the ZigBee protocol.The wireless network is constructed by deploying sensor nodes

which collect such physical parameters and environmental information such as vehicle speed

traffic flow

ambient temperature

road noise and vibration so as to achieve the aim of vehicle supervision.This system is simulated by using OPNET Modeler and the network simulation results in different topologies

traffic flows and node failures are discussed and the network performances evaluated

providing a reliable and quantitative basis and reference for the network planning and system construction.