Use of speed monitoring display with changeable message sign to reduce vehicle speeds in South Carolina work zones

With the presence of an extensive and excellent road network, the need to restore, resurface, or replace parts of a roadway will always exist. This directly gives rise to the presence of work zones in which workers perform maintenance and construction tasks on an existing roadway in close proximity with moving vehicles. The transportation engineer is responsible for setting up these work zones to balance three goals: the timely completion of the construction or maintenance work, the preservation of the capacity of the roadway and, most important, the safety of the workers. With an aim to achieve increased safety in highway work zones, there are several different techniques that should be considered. These include keeping drivers alert, aware, and awake; making workers and the work zone more visible; improving the control of traffic in merging areas to make lane changes more predictable; developing better safety devices; and reducing vehicle speed and speed variance in the work zone. This research focuses on the last of these techniques, reducing vehicle speeds, through the implementation of a speed monitoring display with changeable message sign.; Speeding is a major problem for work zone safety and, as a result, there is a need to develop more effective traffic control devices. In an effort to reduce speeds in work zones, a research project, led by Clemson University researchers, was initiated to develop several effective traffic control devices for use in South Carolina work zones. These efforts involved the use of a static speed activated message sign, drone radar, and a portable changeable message sign. Work zone speeds have customarily been regulated by standard regulatory or advisory speed signs]. However, most drivers do not slow down in response to these static speed control measures.; Advances in technology require the development of a new and unique device capable of displaying driver speed as well as a dynamic message. This thesis focuses on the evaluation of such a device on its effectiveness to reduce speeds in work zones. Previous studies have been performed which examine the use of generic speed monitoring displays that only show the current travel speed of a vehicle as well as the speed limit and depend on the driver behavior to slow down. The speed monitoring display with changeable message sign not only displays the driver speed but also displays a message based on the speed limit and the speed of the vehicle. Research was conducted in both construction and maintenance work zones in South Carolina, and the effectiveness of different messages was determined. Additional research, using a different set of message sequences, was conducted on the use of the sign as an advance indication for the presence of enforcement at the site.; The speed monitoring display with changeable message sign displays the speed of the approaching vehicle and activates different messages depending on the speed at which the vehicle is traveling. The effectiveness of the sign was tested based on the mean speed, 85th percentile, and the percentage of vehicles exceeding the speed limit. It was found that the sign gives excellent results with a significant reduction of speeds in work zones. In general, it was found that the message targeting specific drivers had the maximum impact on the reduction of speeds. Lastly, this thesis provides suggestions and improvements for the use of the speed monitoring display with changeable message sign for better work zone safety.