Data Accuracy Oriented Method for Deploying Fixed and Mobile Traffic Sensors Along a Freeway

A data accuracy oriented method was developed in this study to deploy fixed and mobile traffic sensors. Two approaches: a multi-objective optimal method and a simulation method, for optimizing the location and the number of single-type sensors were first introduced. Several schemes of combing the fixed and mobile sensors along a freeway in terms of sensor number and data accuracy were then analyzed. By adopting the Mean Absolute Percentage Error (MAPE) of segment average speed as a criterion to evaluate these combination schemes, the optimal multi-type sensor combination scheme was determined. An illustrative example on a freeway section of State Route 78 was given to clarify the effectiveness of the proposed method. The results indicated that the proposed method is effective and also feasible in solving multi-sensor combination problem; sensors can be arranged in an optimized manner to avoid redundancy by the proposed method. The result also indicated that the combination of fixed and mobile sensors is superior to deploying single type sensor along a freeway.