A new study by the AAA Foundation for Traffic Safety finds that raising posted speed limits may do little to save time and increase traffic flow but could lead to more crashes, injuries, and deaths.
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. Click here to view the full report
“The movement in statehouses to raise speed limits is happening across the country in at least eight states this year,” said Jennifer Ryan, director of state relations for AAA. “But the benefits are overrated, and the risks are understated. Increasing speed limits does not always yield the positive results envisioned by traffic planners.”
Key findings from AAA’s study:
- Raising posted speed limits was associated with increased crashes on two of three interstate highways.
- Lowering posted speed limits led to fewer crashes in many cases examined. But the likelihood of speed limit violations increased after lowering posted speed limits, suggesting the need for better public awareness education tied to these changes.
- Changes in travel times were small in response to both raised and lowered speed limits.
“Our study found no one-size-fits-all answer regarding the impact of changing speed limits,” said AAA spokesman Mark Jenkins. “AAA urges transportation officials to apply a “holistic” approach when setting or changing posted speed limits and prioritize safety over speed and capacity.”
Speeding is a major factor in vehicle crashes across the country.
The National Highway Traffic Safety Administration says there were more than 42,000 traffic deaths in 2021 and in 2022. The highest number in 16 years.
The agency says speeding was a factor in nearly 29% of the deaths in 2021 and 27% in 2022.
Florida is one of the most dangerous states for driving. There were over 3,700 traffic fatalities in 2021. However, Florida had the lowest percentage of deaths related to speeding. The state still has the third highest number of crash fatalities overall.
AAA says the changes in time spent on the road were very small when it came to speeding.
The latest results are from the third phase of the AAA Foundation’s research into the effects 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.
