Wireless Sensor Networks for Traffic Congestion Monitoring

Wireless magnetic sensor networks offer an attractive, low-cost alternative to inductive loops, video and radar for traffic surveillance on freeways, at intersections and in parking lots. The network comprises 5- diameter sensor nodes (SN) glued on the pavement where vehicles are to be detected. The SNs send their data via radio to the -access point- (AP) on the side of the road. The AP forwards sensor data to the Traffic Management Center via GPRS or to the roadside controller. Because such networks can be deployed in a very short time, they can also be used (and reused) for temporary traffic measurement. Vehicles are detected by measuring the change in the Earth-s magnetic field caused by the presence of a vehicle near the sensor. This paper proposes a simple, yet, powerful system for real time vehicle identification. Wireless sensor nodes are used because of their low cost and the flexibility they provide during deployment.