Motorists in a hurry might view a higher speed limit as a benefit, but according to a new study by the AAA Foundation for Traffic Safety, raising posted speed limits may do little to save time and lead to more crashes, injuries, and deaths for motorists, pedestrians and cyclists.
Speeding is a critical factor in vehicle crashes across the nation. According to the National Highway Traffic Safety Administration (NHTSA), there were more than 42,000 traffic deaths in 2021 and again in 2022, the highest levels in 16 years. NHTSA reports that speeding was a factor in nearly 29% of the fatalities in 2021 and 27% in 2022.
"After studying a dozen roadways where posted speed limits were raised or lowered, our analysis found there is no one-size-fits-all answer about the impact of these changes," said Theresa Podguski, director of legislative affairs, AAA East Central. "What the Foundation study does show is it is critically important to consider the safety implications when making any changes to posted speed limits.”
The AAA Foundation’s research results varied across all 12 roadway sites examined. All had new posted speed limits— six raised and six lowered— and included various road types.
Key Study Findings
- Raising posted speed limits was associated with increased crash frequencies for two of the three Interstate Highways examined.
- Lowering posted speed limits was associated with decreased crash frequencies for one of the two principal arterials examined. However, the likelihood of speed limit violations increased with lower speed limits, suggesting the need for better public awareness education about these changes.
- Changes in travel times were small in response to both raised and lowered speed limits.
AAA urges transportation officials to apply a comprehensive approach when setting or changing posted speed limits and prioritize safety over speed and capacity. The Foundation recommends that changes in posted speed limits should consider a range of factors, including but not limited to the type of road, surrounding land use, and historical crash data. AAA supports automated speed enforcement, but programs must be carefully implemented to maintain community support, prioritize equity and consistently drive improved safety.
This study is the third phase of the AAA Foundation 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. In the second phase, crash testing revealed that small speed increases have severe and potentially deadly effects on crash outcomes.
AAA Foundation for Traffic Safety
Established in 1947 by AAA, the Foundation for Traffic Safety is a nonprofit, publicly funded 501(c)(3) charitable research and educational organization. The AAA Foundation's mission is to prevent traffic deaths and injuries by researching their causes and by educating the public about strategies to prevent crashes and reduce injuries when they do occur. This research informs the development of educational materials for drivers, pedestrians, bicyclists, and other road users.
AAA East Central is a not-for-profit association with 69 local offices in Kentucky, New York, Ohio, Pennsylvania and West Virginia serving 2.7 million members. Past news releases are available at news.eastcentral.aaa.com. Follow us on Twitter and Facebook.