A VEHICLE PRESENCE DETECTION SYSTEM

摘要

A system (22) and method which can detect the presence of a vehicle within the protected area (32) of a four gate railroad crossing (30), determine its location and direction it is moving in, and open an appropriate exit gate to allow the vehicle to escape prior to the arrival of a train at the crossing. The system has a series of magnetometer sensors (41-46) suitably placed in the crossing to detect the presence of a vehicle. The sensors are connected to a controller (23) which analyzes readings from the sensors. Upon the approach of a train, the controller, based on analysis of readings from the sensor, determines if a vehicle has become entrapped and determines which exit gate (35 and 39) must be opened or should remain open to allow the entrapped vehicle to escape. The system also has self test capabilities as well as the ability to continuously update, when no vehicles are present, a baseline reading of the ambient magnetic condition of the crossing area, which baseline the controller uses in analyzing data from the sensors.