Effect of Vehicle Lane Position on Approaches to Construction Zone Lane-Drop Joint Merges

To maintain safety and mobility in work-zone lane closures, traffic control devices such as signs, barricades, and other devices are placed in advance of and within the work-zone to inform, warn, and guide drivers and help them maintain proper positioning as they transition into the appropriate lane(s). These devices also serve to promote a smooth, safe, and orderly merging maneuvers and create a protective buffer for construction workers. However, empirical evidence suggests that as traffic approaching the work zone increases to capacity levels, the arrangement of traffic control may limit the efficiency of flow and contribute to driver dissatisfaction in these areas. This paper describes the results of a recent research effort to develop and test a new approach to address the recognized shortcomings of current work zone lane drop merge areas. This new design, known as the “Joint Merge,” seeks to build upon the results of several recent research studies and innovative designs used in Europe to bring a more intuitive perspective to the process of merging at lane drops. The research was also unique in that it involved a comparative field assessment of a Joint Merge to a conventional Manual on Uniform Traffic Control Devices (MUTCD) under live traffic conditions. In the paper lane utilization is used to determine how drivers react to the new form of control and how operational conditions are affected at various points leading up to and within the work zone traffic control area.