Research on Speed Limit of Work Zones in the Freeway

The aim of the study was to develop a procedure for determining freeway work zone speed limits usable during the construction phase of a roadway maintenance project. The most desirable work zone speed limit should minimize the accident rate as well as ensure the capacity. Research by others showed that accident rates increase with deviation from the mean speed, so the speed limit should minimize the speed standard deviation. To save time, the method of microscopic simulation was utilized. The parameter set of the microscopic simulation model for work zones in the freeway was validated by using the data collected in the work zones by means of orthogonal experimental design. The simulations were run for various traffic volumes and compositions and the model between the speed limit and the speed standard deviation was built as well. The result is that speed limit lowered by 30 km/h downwards in work zones compared to the upper section can decrease the speed standard deviation and the potential accidental rate the most and the capacity can be maintained at the same time.