Optimal subwork zone operational strategy for short-term work zone projects in four-lane two-way freeways

Roadside trees in Singapore are regularly trimmed for the purpose of traffic safety and roadside tree-trimming project is one typical type of short-term work zone projects. To implement such a short-term work zone project, contractors usually divide an entire work zone into multiple subwork zones with the uniform length. This paper aims to determine an optimal subwork zone strategy for the short-term work zone projects in four-lane two-way freeways with time window and uniform subwork zone length constraints. The deterministic queuing model is employed to estimate total user delay caused by the work zone project by taking into account variable traffic speeds. Based on the user delay estimations, this paper proceeds to build a minimization model subject to time window and uniform length constraints for the optimal subwork zone strategy problem. This paper also presents a variation of the minimization model to examine the impact of unequal subwork zone length constraint. Since these minimization models belong to the mixed-integer non-differentiable optimization problems, an iterative algorithm embedding with the genetic simulated annealing method is thus proposed to solve these models. Finally, a numerical example is carried out to investigate the effectiveness of the proposed models. Copyright (c) 2010 John Wiley & Sons, Ltd.