Temporary Movable (“Zipper”) Barrier systems in work zones

WSDOT owns a couple of the movable barrier systems and has used them primarily on interstate freeway HOV widening projects over the past several years. They work well in adding an additional level of safety to the work area by providing positive protection that is not available when using standard traffic control devices in lane closure operations. The system is not the best solution for all locations or for every work operation but it does work well in a linear, long-term stationary work zone such as these widening projects. One thing to remember is that when using the movable barrier in a lane closure scenario all the standard lane closure signing and devices are required in advance of the barrier.
WSDOT has not developed any specific design standards for the use of the barrier. Each location has been project-specific and unique to the work operation. The only part of the system that has required special attention is the storage of the actual transfer device due to its size and the need to straddle the barrier in order to move it. Typically traditional temporary concrete barrier with an attenuator on the shoulder has been required in advance of the movable barrier to protect the transfer device and allow for a transition area to move the barrier into place.