Motorists' Speed Response to Nonvariable and Variable Work Zone Speed Limits and Other Work Zone Conditions

Transportation professionals view the setting of appropriate regulatory speed limits on public roads, including those under repair or reconstruction, as an important tool in promoting safe and efficient operations. The Ohio Department of Transportation sponsored a study to evaluate its work zone speed zoning processes. Researchers observed motorists' speed choices upstream of and adjacent to several combinations of work zone conditions and factors that were used to justify reduced speed limits in Ohio work zones. Researchers also observed motorists' speed choices upstream of and within pilot variable work zone speed zones. Researchers confirmed that motorists reduced their speed only if they clearly perceived a need to do so. Therefore, whenever possible, the first work zone speed limit sign should be installed within view of a work zone condition. In general, the speed reduction downstream of the first nonvariable and variable work zone speed limit signs ranged from 1 to 6 mph and 3 to 11 mph, respectively. In addition, researchers found that the speed reduction on entering a lane shift, within a lane closure, and on entering a median crossover ranged from 4 to 15 mph. On the basis of previous research and the results of the studies documented in this paper, the research team developed work zone speed zone guidelines for multi-lane highways with original posted speed limits greater than or equal to 55 mph. Researchers also made recommendations for where variable work zone speed zoning should be considered.