Effectiveness of Changeable Message Displays in Advance of High-Speed Freeway Lane Closures

The objective of the research reported herein was to determine effective advance-message presentation (e.g., display type, message content, placement distance) for lane closures on high-speed freeways. This report provides, as a result of field studies at selected lane-closure sites, an objective analysis of traffic performance in response to various changeable-message displays. Field tests were conducted at work zones in Charleston, SC; Macon, GA; Boulder, CO; and Escondido, CA. Devices that were tested included 3-line and 1-line bulb matrix signs and a 2-line rotating drum sign; data were also collected for a base condition without a sign for comparison purposes. Data collection techniques included driver questionnaires and interviews and manual recording of traffic operational data (e.g., lane change location, speed). Both right- and left-lane closure were studied, but a suitable site with a center-lane closure could not be located. Similarly, information obtained for the unplanned condition (e.g., an accident) was quite limited because of the unpredictable and short duration nature of the occurrences. The general findings from the field studies are reported herein; more detailed accounts of the results from each individual field site are included in Volume II of the agency report, ” Effectiveness of Changeable Message Displays in Advance of High-Speed Freeway Lane Closures–Appendixes E-G.” NCHRP Project 3-21(2) was one of many studies being conducted in the late 1970s and early 1980s related to traffic control in work zones. These studies were sponsored by the FHWA and the NCHRP and provide information on arrowboards, traffic cones, tubes, barricades, and markings. As a result, considerable information is now available on the effectiveness of individual control devices; however, there remains a need for a comprehensive study of alternative combinations of devices.