The objective of this project was to evaluate the effectiveness of two interventions on the reduction of travel speeds in highway work zones: (i) Rumble Strips, and (ii) Variable Message Signs (VMSs). While the injury rate in total U.S. construction has declined @ 2.9% per year, and the fatality rate in U.S. transportation has declined @ 3.2% per year, the severe injuries in highway work zones have stayed constant at approximately 37,000, and fatalities at 800, for the last several years, costing about $4.0 billion per year. 'Excessive Speed', and 'Driver Inattention' have been found as the two major causes of highway work zone accidents accounting for 41.9% of the work zone injuries. The effectiveness of the proposed interventions was evaluated in mitigating these two major causes. The proposed interventions have the potential of reducing 168 fatalities, and 7,752 severe injuries; and save $838 million. Three field studies were conducted. A field study was done in the first year of this research on the effectiveness evaluation of Variable Message Signs (VMSs) in reducing vehicle speeds in highway work zones. Three types of VMSs: (i) WORK ZONE 45 MPH PLEASE SLOW DOWN, (ii) WORK ZONE 45 MPH - STATE POLICE ENFORCED, AND (iii) YOUR SPEED 'X' MPH, were tested on highway repaving jobs on Interstate-90 in the western New York region, all of the sections having a speed limit of 65 mph, with a posted speed limit of 45 mph in the work zones. All of the tests were conducted in the nighttime because the repaving work was scheduled during nights when the traffic volumes were light. The tests showed that a VMS can effectively reduce speeds by about 5 mph. The VMS: WORK ZONE 45 MPH - PLEASE SLOW DOWN, reduced mean speeds by 6mph, against 5 mph by the VMS: YOUR SPEED "X" MPH. The tests also showed that the VMS reduced the percentage of vehicles above 45 mph by about 8%. On this attribute, the VMS: WORK ZONE 45 MPH - STATE POLICE ENFORCED, performed the best. It reduced the percentage of vehicles above 45 mph by 25% in the driving lane. The VMS control also reduced the percent of vehicles above 55 mph by 25% in the driving lane and 20% in the passing lane, and decreased the percent of vehicles traveling above 65 mph by 8% in the driving lane and by 4% in the passing lane. The speed variances, were however, slightly increased by the application of the VMS's. The VMS's: WORK ZONE 45 MPH,... STATE POLICE ENFORCED, and YOUR SPEED 'X' MPH, reduced the 85th percentile speeds of all vehicles by at least 5.5 mph. Another field study was conducted on Interstate-90 in western New York State (NYS). The study included speed measurements of nearly 180,000 vehicles. The three types of CMS messages tested were: (i) RIGHT LANE CLOSED ,... KEEP LEFT, (ii) WORK ZONE MAX SPEED 45 MPH - BE PREPARED TO STOP, and (iii) LEFT LANE CLOSED,... KEEP RIGHT. Of the three CMS messages tested, the CMS message stating' WORK ZONE MAX SPEED 45 MPH - BE PREPARED TO STOP' proved the best, significantly reducing vehicle speeds by 3.3 mph to 6.7 mph (5.3 km/h to 10.8 km/h). The other two VMSs were not very effective. The third field study was conducted on two highways located in western New York State (NYS) to evaluate two types of speed control devices: (i) Rumble Strips, and (ii) Police Presence. The study included speed measurements of approximately 554,400 vehicles. Two types of rumble strips, composed of preformed rumble strip materials were installed using different patterns, and evaluated. The rumble strips utilized on Interstate-86 were effective in reducing vehicle speeds in the range of approximately 1.4 mph to 2.9 mph (2.25 km/h to 4.67 km/hr), the passenger cars (PC) speeds were reduced by approximately 2.4 mph (3.86 km/h), the 2-axle 4-tire vehicle speeds by as little as 1.4 mph (2.25 km/h). The 5A-ST vehicles were reduced by as small as 2.0 mph (3.22 km/h) but were dependent upon the type of lane closure setup. The other type of rumble strip installed on Interstate-990, was not effective in reducing vehicle speeds in either lane. Police Presence combined with rumble strips was utilized as another speed control measure and was proven to be most effective, reducing speeds of all major vehicle types anywhere from 3.0 mph to 6.0 mph (4.83 km/h to 9.66 km/h). The results of this field research indicate that properly selected speed control devices can be effective in reducing vehicle speeds in highway work zones. The study also proved that rumble strips are at most partially effective, and the police presence combined with rumble strips was the most effective speed control device. Three organizations collaborated in this research: (i) Construction Safety and Health Institute (CSHI), State University of New York at Buffalo, (ii) Thruway Authority, New York State Department of Transportation (NYSDOT), and (iii) Flasher Handling Corporation.
University of Buffalo, The State University of New York, Department of Civil, Structural and Environmental Engineering, 223 Ketter Hall, Buffalo, NY 14260