Vehicle Speeds in Work Zones: An Objective and Subjective Analysis

This study examined quantitatively and qualitatively the speed characteristics and drivers’ compliance with the posted speed limit using objective and subjective data analysis, respectively. Nine data sets from different configurations of four work zones on I-44 in Missouri were used for the objective evaluation. Parametric statistical tests were performed for the evaluation of the speeds of cars and trucks. The effects of lane closure, lane width reduction, and construction activity on speeds of vehicles were studied. Construction activity had a significant effect in reducing the speeds of vehicles. Results indicated that the speeds of vehicles were statistically higher than the posted speed limit for most cases except when lane width was reduced using tubular markers inside the open lane. The subjective evaluation investigated the drivers' perception of driving through the work zones by using a survey questionnaire. Specific questions were related to safety, drivers’ preference for different signage distances before the work zone, drivers’ actual speed versus posted speed limit and compliance, delay in work zones, and the effect of construction activity on their speeds. Results were consistent with the objective evaluation and showed that the drivers prefer to be well informed more than a mile from the work zone. More than 87% of drivers moved out of the closed lane before they could actually see the work zone. More than 60% of drivers experienced delay and 92% agreed that construction activity reduced their speeds which were also found from the results of the objective analysis.