AAA Study On Raising Speed Limits: Is It Worth The Risk?

The American Automobile Association is warning policymakers about the dangers of raising speed limits to help with traffic flow, saying even modest speed increases can have a huge impact on the likelihood and severity of injuries in a crash.

The AAA points to new crash tests conducted by the AAA Foundation for Traffic Safety, the Insurance Institute for Highway Safety (IIHS) and Humanetics that show small speed increases can have huge effects on crash outcomes. The safety organizations conducted crashes at three different impact speeds: 40, 50 and 56 mph. Researchers found the slightly higher speeds were enough to increase the driver�s risk of severe injury or death.

�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.�

As the crash speed increased in the tests, researchers found more structural damage and greater forces on the dummy�s entire body.

Here�s a breakdown by speed:

• At the 40 mph impact speed, there was minimal intrusion into the driver�s space.
• But at the 50 mph impact speed, there was noticeable deformation of the driver side door opening, dashboard and foot area.
• At 56 mph, the vehicle interior was significantly compromised, with the dummy�s sensors registering severe neck injuries and a likelihood of fractures to the long bones in the lower leg.

�Our crash test dummies are instrumented with hundreds of sensors to measure the injury risk so that we understand the scientific limits of safety and injury prevention. Understanding that the risk of serious and permanent injury becomes significantly higher in crashes beyond statutory speed limits clearly demonstrates why there are limits in the first place,� commented Jack Jensen, vice president of engineering at Humanetics.

Furthermore, AAA researchers say at both 50 and 56 mph, the steering wheel�s upward movement caused the dummy�s head to go through the deployed airbag. This caused the face to smash into the steering wheel. Measurements taken from the dummy showed a high risk of facial fractures and severe brain injury.

Test Vehicle

Three 2010 Honda CR-V EX crossovers were used in the testing, since the 2010 model represented the average age of a typical vehicle in the U.S, which is 11.8 years. That particular model also earned the top rating in the IIHS moderate overlap front test. (Calspan Corporation conducted all the tests in its crash laboratory in Buffalo, New York.)

Speed Limit Enforcement

The AAA is also urging policymakers to correctly set and enforce speed limits, rather than raise them to meet driver habits. Today, it says 41 states allow 70 mph or higher speeds on some roadways, and that includes 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.

�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. This includes using proven countermeasures like high-visibility enforcement and carefully implemented speed-camera programs to consistently and equitably enforce speed limits 24/7.�

AAA says speed limits should not be raised or lowered only to manipulate traffic volume on a particular roadway. It urges states 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 Jake Nelson, AAA director of traffic safety advocacy and research.

For more information about the study click here.