Raising Speed Limits Can Cause Fatal Crash Rates To Spike, Offers Few Benefits: Study

A new study from AAA found that, on the whole, raising speed limits does little to benefit drivers in terms of travel time and goes a long way towards raising crash and fatality rates, especially on busy urban corridors.

Forget Autonomy, Drivers Still Want Control

We’ve been saying it for a while, but we’ll say it again: Relying on unregulated private car ownership as the dominant form of transportation is dangerous and unhealthy to the public. AAA watched crash rates on 12 different types of roadways in both urban and rural areas that were experiencing speed limit adjustments. Six of the roads in question had their speeds lowered, while the remaining roads saw speed limits go up.

In its research, AAA found raising limits led to an increase in crashes on two of the three interstate highways. Meanwhile, a decrease of speed limits saw a reduction in crashes, but also higher rates of speeding. Meanwhile, the effect of raising or lowering the speed limit on commute times was negligible.

“Our study analyzed before-and-after data on a dozen roadways that raised or lowered posted speed limits and found no one-size-fits-all answer regarding the impact of these changes,” Dr. David Yang, president and executive director of the AAA Foundation, said in a press release. “However, it is critical to consider the safety implications when local transportation authorities contemplate making changes with posted speed limits.”

We saw this rise in speed limits contribute to a spike in crashes and deaths on Michigan roads three years ago, when the speed limit was pushed up to 75 miles per hour, leading to a 17.2 percent rise in auto crashes. The Institute for Highway Safety also found that reducing speeds in Seattle contributed to a 17 percent decrease in crashes.

Excessive speed isn’t just a factor in fatal crashes — it’s a huge cause. In 2022, excessive speed played a role in 27 percent of fatal crashes, AAA reports. In 2019, NHTSA says 9,478 Americans died in crashes where law enforcement noted speed as a factor. Europe is combating the speed problem with Intelligent Speed Assistance, which causes cars to lose throttle responsiveness when they exceed a certain speed. While the system can be shut off, it still affects driver’s speeding even when it is disengaged by the driver, studies from Norway and Sweden found.

Not that we will ever have such tech monitoring our roads. AAA says that safety and “doing no harm” should be forefront in urban planners minds, but the go fast, be independent culture of the U.S. is not one that will be easily discarded.