Transit operations are often disrupted by stochastic variation of traffic conditions and passenger demand, which increases the variance of operating headways thus increasing the average passenger wait time. Dynamic operational control strategies are critical to regulate headway/schedules and reduce the average wait time. In this study, a dynamic headway control model is proposed to maintain desired headways for any pair of successive vehicles. The objective total headway variance function is minimized dynamically whenever a vehicle departs from a station. The vehicle arrival time at the immediate downstream station is optimized while considering the maximum attainable operating speeds and the predicted arrive and departure times at all downstream stations. The proposed model is validated by simulating a hypothetical high frequency light rail transit (LRT) route, while the results demonstrate that the proposed model is very effective in regulating headways as well as reduce average passenger wait times. (A*)
Abstract