Dynamic Late Merge Control Concept for Work Zones on Rural Interstate Highways

Conventional traffic control plans for lane closures of rural interstate normally work well as long as congestion does not develop. However, when the traffic demand exceeds the capacity of the work zone, queues may extend back passed the advance warning signs, often surprising approaching traffic and increasing the accident potential. Also, smooth and orderly merging operations may be lost as some drivers remain in the closed lane attempting to squeeze into the open lane at the head of queue while other drivers try to prevent drivers in the closed lane from passing them by straddling the centerline or traveling slowly in tandem with another vehicle in the closed lane. These maneuvers tend to reduce the capacity of the merging operation and increase the accident potential and road rage among drivers. The Early Merge and Late Merge are two forms of merge control designed to deal with these problems. However, they also have operational characteristics that limit their effectiveness under both congested and uncongested traffic flow conditions. This paper examines the advantages and disadvantages of each approach. It then describes a new concept called the Dynamic Late Merge, which features the integration of the Late Merge and the conventional lane closure merge control based on real-time measurements of traffic conditions in advance of the lane closure.