Small speed increases can have huge effects on crash outcomes, as shown in new crash tests by the AAA Foundation for Traffic Safety, the Insurance Institute for Highway Safety (IIHS) and Humanetics. The safety organizations conducted crashes at three different impact speeds (40, 50 and 56 mph). They found the slightly higher speeds were enough to increase the driver’s risk of severe injury or death.
Data from the National Highway Traffic Safety Administration (NHTSA) shows that since 2010 in Massachusetts, there have been more than 22,000 injury crashes involving unsafe speeds, including more than 2500 serious injury crashes. And from June to November 2020, more than 200 speeding tickets were issued each month to drivers speeding 100 miles per hour or higher—while 2019 saw no months with that number of speeding tickets. More speed-related crashes occur on Fridays and Saturdays, and Boston, Springfield, Worcester, Brockton and Lowell record the highest numbers of speed-related crashes.
Drivers often travel faster than posted speed limits, but when officials raise limits to match travel speeds, people still go faster. Today, 41 states allow 70 mph or higher speeds on some roadways, including eight states that have maximum speeds of 80 mph or more. A 2019 IIHS study found that rising speed limits have cost nearly 37,000 lives over 25 years. AAA and IIHS urge policymakers to factor in this danger from higher speeds when considering speed limit changes.
“We conducted these crash tests to assess the effect of speeds on drivers and learned that a small increase could make a big difference on the harm to a human body,” said Dr. David Yang, executive director of the AAA Foundation for Traffic Safety. “A speeding driver may arrive at their destination a few minutes faster, but is the tradeoff of getting severely injured or even losing one’s life worth it if a crash occurs?”
“Higher speed limits cancel out the benefits of vehicle safety improvements like airbags and improved structural designs,” said Dr. David Harkey, IIHS president. “The faster a driver is going before a crash, the less likely it is that they’ll be able to get down to a survivable speed even if they have a chance to brake before impact.”
When correctly set and enforced, speed limits improve traffic flow and maximize all public road users’ safety.
“Cars are safer than they’ve ever been, but nobody’s figured out how to make them defy the laws of physics,” said Harkey of IIHS. “Rather than raising speed limits, states should vigorously enforce the limits they have.”
Speed limits should not be raised or lowered only to manipulate traffic volume on a particular roadway. States are urged to use engineering and traffic surveys when setting maximum speed limits.
“Policymakers need to also think beyond enforcement to control speeds and should consider infrastructure changes based on road type to calm traffic flow appropriately so that posted speed limits are followed,” said Mary Maguire, Director of Public and Government Affairs.
This study is the second part of the AAA Foundation for Traffic Safety research examining the effect of posted speed limit changes on safety. In the Foundation’s first study, traffic engineers were asked how posted speed limits are set and what factors they consider in changing them.