The Effects that Speed Limits Have on Auto Accidents

Numerous studies have been carried out nationwide to tackle the question: Do higher speed limits affect the rate of traffic accidents and fatalities? Unfortunately, there is no one answer set in stone.
Studies have produced results that vary from state to state. Findings in the Midwest were significant in that fatality and injury rates following speed limit increases were noticeably higher than before, while the same did not go for California. Road hazards, weather conditions and driver behavior differ countrywide.

A method known as the “85th percentile” is used by traffic engineers to establish speed limits. This tactic operates under the assumption that most drivers will travel at a speed that is reasonable, sensible and comfortable to them on any given roadway, regardless of the posted limit. Speed limits are set at a number that separates the bottom 85% from the top 15%. For example, if the speeds of 100 vehicles are measured and 85 vehicles are traveling at 37 mph or less, the speed limit for the road could be set at 35 mph.

Experts essentially split down the middle when it comes to whether they think higher speed limits contribute to traffic accidents and fatalities. In 2000, the Automobile Club of Southern California performed the first in-depth analysis of effects of higher speed limits in California. The study showed that higher speed limits set in 1995 and 1996 did not increase the rate of fatal or injury traffic crashes. In fact, actual travel speeds on roads with increased speed limits barely changed. People were already traveling faster than previous speed limits, and once speed limits were altered they generally did not speed faster than their comfort zone.

A 41-mile stretch of Texas 130 toll road now has the highest speed limit in the nation, and allows drivers to legally drive up to 85 mph. Proponents of the increased speed limit refer to data that demonstrates that in the years up to the most recent increase in speed limits, speeds were generally increasing however death rates were not. On the other hand, safety experts in the U.S. and Europe warn Texas lawmakers that fatalities and injury accidents are likely to rise. Steve Bloch, Ph.D. of the Auto Club stressed that "Faster-moving vehicles are more likely to crash because the driver has less time to brake and a smaller margin of error in an emergency. Faster-speed crashes are also more likely to result in injury or death because fast-moving objects hit with greater force than slow-moving ones."

Although findings across the country are conflicting, they have shown that drivers are by-and-large practical and cautious. In essence, posted limits are not the cause of auto accidents – reckless driving is.