Monitoring free flow traffic using vehicular networks

We present DTMon, a dynamic traffic monitoring system using vehicular networks, and analyze its performance in free flow (i.e., non-congested) traffic. DTMon uses roadside infrastructure to gather and report current traffic conditions to traffic management centers and equipped vehicles. We analyze how traffic characteristics such as speed, flow rate, percentage of communicating vehicles, and distance from the DTMon measurement point to the roadside infrastructure affects the amount and quality of data that can be gathered and delivered. We evaluate five different methods of delivering data from vehicles to the roadside infrastructure, including pure vehicle-to-vehicle communication, store-and-carry, and hybrid methods. Methods that employ some amount of store-and-carry can increase the delivery rate, but also increase the message delay. We show that with just a few pieces of roadside infrastructure, DTMon can gather high-quality travel time and speed data even with a low percentage of communicating vehicles.