Typically, speed limits are reduced in work zones to safely accommodate construction activities and motorists on the roadway. This paper presents a methodology to evaluate the temporal and spatial effects of techniques designed to encourage compliance with work zone speed limits. The evaluations were performed over short and long segments within and adjacent to an Interstate construction work zone in suburban Indianapolis, Indiana, with the use of vehicle probe data. Space mean speed was measured by using 13 Bluetooth probe data acquisition stations, which provided a random sample of unique identifiers for approximately 11% of the passing vehicles. These space mean speed data were used to compute a series of comparisons between a day with no enforcement activity and a day with exceptionally high enforcement. During enforcement, the space mean speed decreased by approximately 5 mph throughout the 12.2-mi study segment. Within 30 min after the enforcement detail ended, however, space mean speeds increased, and there was no statistically significant residual impact on the space mean speed. Even at the absolute peak of enforcement, 75% of the probe vehicles exceeded the speed limit in all but one of the segments that had a posted speed limit of 45 mph. In addition, 25% of the probe vehicles exceeded the posted limit by more than 5 mph in all 45-mph segments during peak enforcement. The study is perhaps the largest ever conducted with respect to concurrent enforcement and extensive space mean measurement. The data represent an upper bound on the impact of enforcement activity on work zone speeds and should be of interest to public agencies as they consider compliance techniques.

Prepared in cooperation with the Indiana Department of Transportation and Federal Highway Administration. AbstractOverweight trucks shorten highway life and indirectly increase the costs of maintaining roads. Improved methods for enforcement of commercial vehicle weight laws may increase the number of overweight vehicles caught, thereby prolonging highway life. Improved enforcement may also reduce the number of illegally operating vehicles.This report describes the concept of using existing INDOT Weigh-In-Motion equipment, a laptop computer, and wireless communication equipment, to develop a virtual weigh station screening tool. The Virtual Weigh Station screening tool developed in this project allows officers to read the weights of vehicles crossing WIM scales, in real time, in their patrol cars. Giving officers this information increases the chances that the vehicles selected for weighing on portable scales are indeed overweight. This report documents the accuracy and precision evaluation performed on all the candidate WIM sites as well as the new infrastructure required to implement the Virtual Weigh Station concept.The report describes several cases where significantly overweight vehicles were identified and impounded. For example the procedures described in this report, resulted in the identifying the early morning hours as the best time for enforcement in Merrillville. As a result, on May 18, 2001 vehicles weighing 98,700 lbs and 100,600 lbs were stopped. Those vehicles were impounded and resulted in fines of $1,625.00 and $1,735.50, respectively. In February 2002, Commercial Vehicle Enforcement officers stopped ten trucks on US 24 near Fort Wayne using the virtual weigh station. Eight of the trucks were determined to be overweight and fined. The three heaviest trucks weighed 90,200 lbs, 90,900 lbs, and 91,100 lbs resulting in fines of $1, 099.50, $1,169.50, and $1,189.50, respectively. On April 12, 2002, another enforcement was conducted on I-65 near Merrillville. Three trucks were stopped based on the virtual weigh station data. One of the trucks weighed 87,400 lbs, resulting in a $529.50 fine. The report concludes by making several recommendations designed to improve the quality of the WIM data and facilitate wide spread deployment by the Commercial Vehicle Enforcement Division.