Travel Time Reliability Based Highway Work Zone Scheduling

The continued deterioration of highway infrastructure in the US has resulted in an increased number, duration, and scope of work zone projects. Transportation agencies are facing great challenges to schedule and manage work zones efficiently and economically. Existing work zone scheduling models usually assume fixed average traffic impact given a designed work zone schedule. Recently, the incorporation of travel time reliability in evaluating highway facility and traffic improvement projects has drawn increased attention. In comparison to traditional average travel time based methods, it considers the full distribution of travel time under a large number of traffic scenarios such as demand fluctuations, incidents, weather, etc. Thus, incorporating travel time reliability can provide more comprehensive insights into the potential traffic impact of a highway improvement plan and new transportation facilities. However, the existing Highway Capacity Manual (HCM) toolbox of evaluating travel time reliability is complex and inefficient to be integrated into the optimization framework of the work zone scheduling problem. In this study, the authors develop simplified methods that identify and model the work zone impact on travel time and travel time reliability to provide evaluation input for the work zone scheduling problem. Combined with the work zone costs such as the maintenance cost, user cost, and additional accident cost, a new work zone schedule model is proposed that incorporates travel time reliability measures. A genetic algorithm is used to solve this combinational optimization problem. A numeric example is carried out to demonstrate the applicability and effectiveness of the developed model.