Optimal Work Zone Lengths and Signal Timing for Two-Lane Highways Revisited: The Need to Consider Stochasticity

Work zones can give rise to significant costs, both to maintenance agencies as well as to road users. In this paper we focus on the optimal configuration of work zones on two-lane highways. While previous work assumed determinism in the vehicle arrival processes, we relaxed this questionable assumption and allow vehicles to arrive according to some stochastic process. From the existing literature it is not clear whether such a relaxation would lead to different optimal work zone configurations, as compared to when determinism in the vehicle arrival process is assumed. In this paper we demonstrate that work zone configurations based on deterministic queuing theory is no longer optimal in a stochastic environment. Moreover, with the advent of computational power, we propose a practical, computationally feasible simulation optimization procedure to determine optimal work zone configurations. In a numerical case study we show that significant cost savings can be realized, especially when there are multiple work zones and/ or when work zone setup times are long.