Capacity Modeling and Control Optimization for Two-lane Highway Lane Closure Work ZonesAuthor/Presenter: Zhu, Wenbo; Li, Zhibin; Ash, John; Wang, Yinhai; Hua, Xuedong
A two-lane highway lane closure work zone is a unique work zone type due to its traffic impact. As one lane of traffic is blocked, it is necessary to implement a traffic control strategy to effectively serve bi-directional traffic. In the sense that the right of way is allocated between two directions sequentially, traffic control at two-lane highway work zones is similar to signalized intersection traffic control. In order to analyze the problem, this study developed two methods: a mathematical capacity and delay model with calculations based on signalized intersection theory, and a VISSIM micro-simulation model calibrated using field observed data. After fine tuning the parameters, the mathematical model was able to make reasonably accurate delay estimates. The study also recommended a smaller vehicle random arrival adjustment in the stochastic delay model compared to Highway Capacity Manual (HCM) 2010 recommend value for signalized intersections. The developed models were applied to optimize two-lane highway lane closure work zone control management. The delay-capacity diagrams indicate that in order to minimize delay, the roadway capacity should be maintained slightly higher than the traffic demand (specifically, the greater of 1.2 times demand or 200 veh/h higher than the traffic demand). Apart from pre-timed traffic control, a dynamic (actuated) traffic control algorithm is also developed in the micro-simulation model to deal with stochastic vehicle arrivals. In the studied traffic scenario,dynamic traffic control is able to achieve lower delay results than the optimal pre-timed signal control.