Many construction projects require the use of traffic barriers to adequately protect the motoring public and construction workers. Geometric and operational restrictions in these work zones frequently preclude the use of the same design standards for these barriers and terminals that normally apply to permanent systems. One common example involves two-lane, two-way bridges where one-half of the bridge is repaired while maintaining alternating one-way traffic in the remaining lane (usually with temporary traffic control signals). The most common method of traffic control is to install a concrete barrier on the bridge approaches and across the bridge to protect the motorists and workers. While this practice normally provides an acceptable measure of safety for motorists and workers, problems occur when an intersecting highway or driveway that cannot be closed exists near the end of the bridge. In this example, and in other restricted situations, there is often inadequate room to install either the barrier runout at the specified flare rate, an impact attenuator, or other terminal treatments meeting the performance standards for permanent barrier systems. The objective of this research was to develop improved end treatments for temporary traffic barriers, typical traffic control plans, and user guidelines for restricted work-zone situations. This project involved the identification of restricted work zone situations, the classification of specific situations into groups having similar traffic, site, geometric, and terrain characteristics, the development of conceptual designs for barrier terminal and traffic control treatments for each group, the evaluation of proposed treatments for typical situations considering safety, traffic capacity, user delay, costs, and ease of implementation, the development of detailed designs for barrier terminal treatments, crash testing of the terminal treatments, and the preparation of a user's manual for recommended barrier terminal treatments and special traffic control plans, and guidelines for their use. An informational video was also produced to help disseminate information about the problems of restricted work zones and to introduce the recommendations for improved traffic control treatments. (A)
Abstract