Investigation of Factors Affecting Capacity at Rural Freeway Work Zones

Traffic management in freeway construction zones is a challenging task to traffic engineers. Capacity reduction in the work zone is a one of the causes of the problems. Although many past works investigated the capacity problem at work zone locations, only few of them quantified the capacity factors. The presented study investigated potential capacity factors to develop capacity prediction models. The investigated factors include rain and wind, heavy vehicles, the type of lane drop (left or right), police presence, and presence of a novel traffic control system called Indiana Lane Merge System (ILMS). The capacity study was limited to two-lane roadways on rural freeway with one lane dropped. The results indicate that rainfall, heavy vehicles, police presence, and ILMS presence reduce capacity of work zones. The magnitude of reduction caused by rain and heavy vehicles is similar to the reduction observed on freeway sections without work zones. The reducing effect of ILMS is limited (5-6%). This effect may be temporary and may diminish with drivers’ growing familiarity with the system. The strongest reduction (14%) was observed during police presence near the work zone.