Use of Hybrid Static-Dynamic Signs: A Critical State-of-the-Practice Review

摘要

Traditionally, static signs are used to convey messages to the road users. The need to quickly communicate up-to-date messages to the road users has given rise to the use of dynamic message signs (DMS). A typical DMS includes only dynamic messages. An alternative to DMS is hybrid signs, which display both static and dynamic messages on a single sign. A hybrid sign consists of a conventional retro-reflective static sign that is embedded with one or more relatively small, dynamic, usually light emitting diode (LED) message panels. Potential advantages of hybrid signs over DMS include better legibility, shorter reading time, smaller size, and lower installation, operations, and maintenance costs. This paper provides the first state-of-the-practice review on the use, design, and performance of hybrid signs. It covers hybrid sign applications in different parts of the world, including the U.S., Europe, Australia, and Asia. The application areas reviewed included variable speed limits, lane control, managed lane operations, dynamic rerouting, travel time display, and graphical route information display. Multiple examples of each application, many of which were considered innovative and can potentially be adopted for use in the U.S., were given. Issues related to the applications were discussed and lessons learned were provided.