Changeable message sign displays during non-incident, non-roadwork periods.

This synthesis was prepared about using Changeable Message Signs (CMSs) to display types of messages other than real-time messages for non-recurrent, environmental, special event traffic, and other special problems, as well as AMBER alerts, during non-incident/non-roadwork periods as an alternative to leaving the CMS blank. Guidelines for design and display of CMS messages for incidents and roadwork are available; however, guidelines are not available for non-incidents/non-roadwork periods. This synthesis provides that state of the practice as a first step toward developing guidelines. This report is about the state of the practice as it involves state departments of transportation (DOTs) and toll road, turnpike, and parkway transportation agencies. The primary intent was to identify practices that have proven effective, as well as those that have not. It intends to offer guidance in making more effective uses of CMSs for non-incident/non-roadwork periods. It appears that a division of opinion may still exist among traffic management centers (TMCs) that do not have the capability or need to display travel time information about whether or not it is best to leave the CMS blank during non-roadwork/non-incident periods or to display messages. TMCs reported that some motorists prefer messages, some do not. Objective data are needed to assist TMCs in their decisions. The information presented here is based on an extensive literature review and a nationwide survey of state DOT TMCs and of agencies that operate toll roads. Conrad L. Dudek, Dudek & Associates, Bryan, Texas, collected and synthesized the information and wrote the report. The members of the topic panel are acknowledged on the preceding page. This synthesis is an immediately useful document that records the practices that were acceptable within the limitations of the knowledge available at the time of its preparation. As progress in research and practice continues, new knowledge will be added to that now at hand. (Author/publisher) This report may be accessed by Internet users at http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_syn_383.pdf