Effects of rural variable speed limits system on driver speed behavior

Speed, speed variation, and speed compliance are important factors related to both frequency and severity of traffic crashes. Decreasing the speed variation and increasing the driver compliance levels have been realized as effective methods to improve the traffic safety. Variable speed limits (VSL) systems along rural roadways are an operational strategy used to address speed related safety problems. VSL systems can aid drivers in selecting safe speeds for the current conditions, which is critical on Wyoming roadways where frequent and severe winter weather conditions often occur. To ensure that the VSL systems will be effective, the posted variable speeds need the highest degree of speed compliance from drivers in the corridor. The objective of this research is to determine the effects of the VSL system on driver's speed behavior on rural corridors and provide the guidance for further development of the VSL system in Wyoming. Results showed that the VSL systems were effective in reducing the speed and speed variation as well as increasing the driver compliance during the implementation period. However, drivers showed the different speed responses according to the various VSL implementation levels. Drivers showed a low tolerance for a large speed reduction on the VSL.