Work Zone Driveway Assistance Devices (DADs): Past Research & Evaluation of Display Strategies

The Driveway Assistance Device (DAD) is an experimental device used to direct traffic onto a bi-directional, single-lane work zone from a driveway or side street. This device uses alternating flashing arrows to indicate the traffic flow direction along the work zone segment in order to reduce wrong-way driving. Although several states have experimented with DADs in various work zone settings, there remains a lack of consensus regarding the design aspects and the general effectiveness. To help address these issues, research was performed to evaluate various aspects of the DAD design, including auxiliary sign messages, signal configuration, and arrow color.