Some practical vehicle speed estimation methods by a single traffic magnetic sensor

This paper proposes three practical vehicle speed estimation methods by a single multifunction magnetic sensor. Compared with traditional methods, this algorithm is simple and convenient to be realized. The multifunction magnetic sensor is described and introduced in this work. Next, a vehicle detection algorithm with a linear time complexity is put forward. Through setting two windows and scanning the vehicle waveform, we obtain the points of vehicle approaching and vehicle leaving, which are the bases for vehicle count, headway time, time occupancy, stopping time, detection of vehicle stopping and presence. The detailed detection methods of vehicle stopping and presence are described. We next present some speed estimation methods in detail. According to three speed estimation methods of Vehicle Length based (VLB), Time Difference based (TDB) and Mean Value based (MVB) to get different reference speeds when a vehicle passes over the sensor, we then analyze the applicability of the three methods. At last, we test the speed estimation methods by adoption of field data. Through the comparison with the real speed of 45 vehicles, it shows that the mean absolute errors (MAE) of VLB, TDB and MVB methods are respectively 4.12km/h, 5.90km/h and 4.05km/h and the mean speed errors of the three methods are all less than 1km/h. These errors are suitable for traffic engineering.