Book Description

Static signs are traditionally 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 increasing use of dynamic message signs (DMS). 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 retroreflective 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, operation, and maintenance costs. This report first provides a comprehensive state-of-the-practice review of existing hybrid sign applications in both the U.S. and around the world. The review focused on several application areas, including speed control, parking guidance, travel time and travel distance information, dynamic rerouting information, and graphical route information. Further, it also identifies the companies that manufacture and market hybrid signs in the U.S. It was found that only a small number of sign manufactures have hybrid sign products for applications other than variable speed limit signs. This report then describes an effort to identify potential hybrid sign applications on both freeways and arterials and evaluate them through a focus group study. A total of ten hybrid sign applications were selected and evaluated in terms of their usefulness, understandability, and preference for different sign designs. In total, ten focus groups involving 150 participants of different age, gender, and ethnic groups were conducted. For each application, the participants' responses were analyzed by age group, gender, and education level, and when applicable, by frequency of using toll roads and public transit service. The participants found parking availability information, arrival time information at bus/train stops, comparative travel times for express lane facilities, drawbridge opening, and travel times on distance signs to be particularly useful. However, bus/train arrival time information and drawbridge opening applications, along with other similar countdown applications, were found to have the following two main limitations: their deployment might create confusion when the dynamic information is not present and the signs could potentially encourage speeding.