Impact of the 65 mph Speed Limit on Virginia's Rural Interstate Highways, 1989-1992

About the report:

In April of 1987, Congress passed the Surface Transportation and Uniform Relocation Assistance Act (STURAA), which permitted states to raise their maximum speed limit on rural interstate highways to 65 mph. Virginia's 65 mph speed limit went into effect on July 1, 1988, for passenger vehicles and on July 1, 1989, for commercial buses. This is the final report in a series to examine the 65-mph speed limit in Virginia, and it summarizes Virginia's experience with the 65-mph speed limit from 1989 through 1992. Following the implementation of the 65-mph speed limit, average and 85th percentile speeds increased on Virginia's rural interstates, and fatal crashes and fatalities increased significantly. On Virginia's urban interstates, on which the speed limit remained at 55 mph, there was a smaller increase in average and 85th percentile speeds, but there was a slight, nonsignificant decrease in fatal crashes and fatalities. Absolute numbers of fatal crashes and fatalities were used in this analysis rather than rates because traffic volume increases on interstates are averaged for both rural and urban systems. Thus, if volumes increased more on rural interstates, comparisons of relative rates would be misleading. The data in this report clearly show that speeds, fatal crashes, and fatalities increased on Virginia's rural interstates after the implementation of the 65-mph speed limit. However, these increases appear to have plateaued in the last two years of the study. Reports from other states and from national studies reflect a general increase in travel speeds and fatal crashes on rural interstates, but there is conflicting evidence on whether the 65-mph speed limit is the cause. Likewise, there is conflicting evidence concerning whether differential speed limits for trucks and cars have had an impact on the frequency of crashes in states maintaining such differential limits.

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