As transportation agencies seek to better manage and operate the transportation system, there is an increasing need for traffic condition data across the roadway network. Wireless location technology (WLT)-based traffic monitoring offers the opportunity to directly measure link travel times on a significantly larger portion of the roadway system than is currently monitored. In WLT-based monitoring, the locations of wireless devices (such as cellular phones) in vehicles are monitored. A series of these positions are then used to derive vehicle speeds on links, effectively making the wireless devices probes in the traffic stream. While this idea is conceptually appealing, previous field deployments have not been able to successfully implement this concept. This paper describes the results of a study that used simulation to examine the efficacy of WLT-based monitoring systems under various configurations. Two case studies were used to investigate how WLT system design and roadway network configuration impact the overall effectiveness of WLT-based monitoring systems. Conclusions on how these systems should be designed and where they are likely to function best are also included. The results of this paper show that while first-generation WLT-based monitoring systems can be used to monitor relatively simple networks, additional design refinements are needed before they can be used across a broad spectrum of roadway conditions.
