Quantitative analysis of smooth progression in traffic signal systems

Traffic signal coordination has been widely used to provide smooth progression for platoons on signalized arterials to enhance performance measures such as travel times, number of stops, and delay. Considering smooth progression as the significant factor of coordination, many studies have been conducted to measure the quality of progression. However, none of these studies concentrated on measuring a continuous smooth driving pattern of each vehicle in terms of speed. In order to quantify the smoothness, this paper conducted an analysis of the speed variation of vehicles traveling along a corridor. A new measure, called the smoothness of the flow of traffic (SOFT), was introduced and evaluated for different kinds of traffic control systems. The measure can be used to evaluate how smoothly vehicles flow along a corridor based on the frequency content of vehicle speed. To better understand the impact of vehicle mode, a multimodal analysis was conducted using the SOFT measure. This study was conducted using a simulation model and a system where vehicle trajectory data are available for computing SOFT.