Optimal Trade-Offs between Construction Cost and Traffic Delay for Highway Work Zones

Abstract

Highway work zones often cause traffic congestion, resulting in increased road-user delays and vehicle emissions. These negative impacts of highway work zones can be minimized by a number of mitigating measures such as reducing the length of work zone segments, using the shoulder temporarily for traffic, and working during low-traffic nighttime hours. These work zone layout measures, however, cause an increase in highway construction cost. Accordingly, these tradeoffs between reducing work zone delays and minimizing construction cost need to be analyzed to establish an optimal balance between these two critical and conflicting objectives. This paper presents the development of a novel multiobjective optimization model for highway work zone layouts that is capable of generating optimal tradeoffs between minimizing traffic delays and construction cost. The model was developed in three main phases: formulation, implementation, and performance evaluation. First, the model was formulated to (1) identify all relevant work zone decision variables that affect mobility and cost, (2) model the two objective functions of minimizing work zone delay and construction cost, and (3) represent all practical constraints. Second, the model was implemented using a genetic algorithm to perform the multiobjective optimization computations and enable generating optimal tradeoffs among the two objectives in a single run. Third, the performance of the model was evaluated using an application example of a highway work zone. The results of the performance evaluation phase illustrate the novel and unique capabilities of the model in optimizing work zone layout parameters and generating optimal tradeoffs between minimizing traffic delays and construction cost.