Book Description

In 1987, the Secretary of Transportation and Public Safety created a task force to study the potential effects of raising the speed limit on rural interstate highways in Virginia. In its 1988 session, the Virginia General Assembly passed legislation to increase the speed limit on rural interstate highways to 65 mph for passenger vehicles, but the 55 mph limit was retained for buses and large trucks. After implementation of the higher speed limit on July 1, 1988, the Secretary reconvened the task force to design a study to determine the effects of the changed speed limit. The Virginia Transportation Research Council was again asked to serve a the staff for the task force. The preliminary data provided in this report represent only 5 months of experience with the 65 mph speed limit and are presented for information only. Any conclusions drawn from these data would be inappropriate and perhaps incorrect. After the speed limit for cars was increased by 10 mph, the average and 85th percentile speeds traveled by all vehicles on the rural interstate system increased by 3 mph, to 63 mph and 68 mph, respectively. The average and 85th percentile speeds traveled by trucks and buses, for which the speed limit remained at 55 mph, decreased slightly. Between July 1 and November 30, 1988, there were 44 fatalities in 35 fatal crashes on rural interstate highways in Virginia. This was a 76 percent increase over the 25 fatalities and a 52 percent increase over the 23 fatal crashes for the same time period in 1987. In the states that increased the speed limit, there was a 41 percent increase overall in the number of fatalities, but in states that did not increase the speed limit, there was a 54 percent increase in fatalities--higher than that noted for states that increased the speed limit. Many of the crashes that accounted for the increase in the number of fatal crashes on rural interstate highways occurred on I-81, and all of the multiple-fatality crashes occurred on either I-81 or I-95. In comparison with 1987, the number of fatal crashes in 1988 included 5 more involving vehicles that ran off the road, 4 more involving tractor trailers, and 3 more involving pedestrians. In October 1988, there was an abnormally high number of fatal crashes and fatalities on Virginia's rural interstate highways, but no patterns were found to explain this 1-month abnormality. Because there are not sufficient data to determine the reasons for the increases in fatal crashes and fatalities, data will be gathered over a 5- year period to determine the effect of the changed speed limit on Virginia's rural interstate highways.