Optimal Number and Location of Node-Based Sensors for Collection of Travel Time Data in Networks

Travel time prediction is highly useful in traffic management and planning. The prediction's accuracy relies on the accuracy of the travel time data used. Various sensors are being used to collect travel time data, including link-based and node-based sensors. Recently, a new method in the collection of travel time data was introduced: Bluetooth technology, used to detect Bluetooth devices in vehicles and determine the vehicles' travel times. Bluetooth sensors are generally node-based sensors. Despite the amount of literature available on sensor location problems, the use of node-based sensors to collect travel time data is rarely discussed. Projects that looked at the collection of travel time data with Bluetooth sensors prompted this study of the problem of sensor location in the installation of Bluetooth sensors and, more generally, node-based sensors. The goal of this study is to find the optimal number of node-based sensors and their optimal deployment locations in a network for the collection of highly reliable travel time data. Two formulations are proposed for modeling this problem. The formulations consider a new set of reliability factors. Through these formulations, the sensor location problem can be solved optimally for large networks. The proposed formulations are not restricted to Bluetooth sensors and can be applied to any node-based sensor location problem. Various case studies that use real-world networks are conducted to compare the results obtained from both the proposed formulations with the methodologies available in the literature. The findings of the case studies are reported in the paper.