Evaluating Innovative Sensors and Techniques for Measuring Traffic Loads

In this paper, evaluating the weigh in motion (WIM) sensors and the techniques for measuring traffic loads is presented. To conduct the evaluation of sensors, a remote WIM system is designed and installed. The designed system can be accessed remotely and is capable of conducting data acquisition for multiple sensors including piezoelectric sensors, fiber Bragg grating (FBG) sensor and a novel microwave sensor. Piezoelectric sensors are relatively cheap, but its accuracy is often brought into question. Compared to piezoelectric sensors, FBG sensors with higher accuracy offer a simpler and more explicit load determination algorithm, and the life span of the sensors is longer. However, it is necessary to build a sensor holder for the FBG sensor. In addition to the evaluation of those regular WIM sensors, a novel WIM sensor was developed. It is an active sensor based on the perturbation theory of microwave resonant cavity. The microwave signal generated by a circuit is coupled into the sensor, and the returned signal is measured to determine the load applied to the sensor. The lab test results show the microwave WIM sensor can weigh the load to very high accuracy.