Optimum Length of Single-lane Closures in Work Zones on Rural Four-lane Freeways

The lengths of single-lane closures in work zones on rural four-lane freeways are commonly based on the expected work rate in order to avoid moving the temporary traffic control zone more frequently than once a day and to limit the possibility of interfering with the work activity. However, the analysis presented suggests that this practice may result in single-lane closures that are (a) longer than the lengths that would minimize the sum of the additional road user and traffic control costs and (b) shorter than those that would minimize the traffic control cost. The objective of the analysis presented is to determine the optimum length of single-lane closures in long-term- stationary temporary traffic control zones on rural four-lane freeways that minimizes the sum of the additional road user and traffic control costs associated with the temporary traffic control zone. An equation for the optimum length is derived using the methods of calculus. The equation can be used to determine the most cost-effective and the most economical lengths of single-lane closures on rural four-lane freeways.