Study: Small speed increases have huge effects on crash outcomes
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Study: Small speed increases have huge effects on crash outcomes

| Feb 3, 2021 | Firm News

Improved vehicle safety technology, such as automatic emergency braking, structural improvements and airbags have cut down on the fatality of traffic crashes. Unfortunately, there is another trend that is canceling out some of the benefits of new safety tech: speed limit increases.

A couple of decades ago, the top speed allowed on American roadways was 55 mph. However, speed limits have been rising. As of today, 41 states allow speeds of 70 mph or higher on at least some roads, typically interstate highways. Eight of those states allow speeds of 80 mph. (Hawaii’s top speed on the interstate is 60 mph.)

Traffic researchers know that people exceed the posted speed limit. When the speed limit is raised to reflect the actual speed of traffic, people tend to speed up even more. It’s a tough cycle to break.

In a 2019 study, the Insurance Institute for Highway Safety (IIHS) determined that rising speed limits were costing lives. How many? Almost 37,000 over 25 years. Now, the IIHS has teamed up with the AAA Foundation for Traffic Safety and Humanetics, a crash dummy manufacturer, to study how higher speeds affect the risk of severe injury or death in a crash.

The study found that even modest speed increases were enough to increase the risk of serious injury or death in drivers.

“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 a spokesperson for 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?”

Crashes were conducted at 40, 50 and 56 mph

The researchers chose the 2010 Honda CR-V-EX crossover to crash test. This car represents the average age (11.8 years) of a typical car on an American roadway, and it earned a top rating in the IIHS’s moderate overlap front crash test. Three vehicles were crashed at 40, 50 and 56 mph at a Calspan Corporation laboratory.

This was a “moderate overlap” crash test, which mimics the forces of two vehicles crashing partially head-on. Forty percent of the vehicle’s driver-side front overlaps with the barrier.

The dummies used in the crash were filled with hundreds of sensors to measure injury risk. The idea was to gauge the severity of injuries in a reasonably safe vehicle at the chosen speeds.

Higher speeds here meant catastrophic injury or death

In the 50 and 56 mph crashes, the steering wheel was forced upward and caused the dummy’s head to punch through the airbag, which had deployed, and smack into the steering wheel. The sensors showed a high risk of both facial fractures and serious brain injuries.

According to the IIHS, which has been performing this type of test since 1995, new vehicles routinely earn good ratings when tested at 40 mph.

These results occurred at only 50 and 56 mph, not 60, 70 or 80. The researchers are concerned that policymakers may not realize the difference in survivability between a crash of 40 mph and one at 50 mph.

“Cars are safer than they’ve ever been, but nobody’s figured out how to make them defy the laws of physics,” said a spokesperson for the IIHS.

The researchers recommend that policymakers refrain from raising or lowering speed limits merely to manipulate traffic volume. Instead, policymakers should focus on engineering and traffic surveys when setting maximum speeds — and then enforce those speed limits vigorously. Moreover, they should focus on traffic infrastructure changes that can calm the flow of traffic and encourage drivers to follow speed limits.

Have you been hit by a speeding car? Whether or not they were above the speed limit, the driver could be considered negligent if the speed was inappropriate for the road conditions or if the driver failed to control their vehicle.