By: Allie Reed and Erich Hellmer
In St. Louis, dangerous speeding is a common occurrence and leading cause of our City’s roads becoming more and more dangerous every year. Trailnet’s 2024 Crash Report analyzed vulnerable road user (VRU) crash data for St. Louis City and St. Louis County (see Figure 1). Looking back at data from the past 15 years, the report shows how crashes for VRUs have become deadlier in the City and County in three key ways.
First, the number of pedestrians and cyclists killed has steadily increased each year since, with 73% more deaths in 2023 than 2010. Second, while more motorists are also being killed now than back in 2010, that number has grown less rapidly (+41%) than the figure for people walking and biking — causing the share of fatalities to shift towards VRUs. People walking and biking now mae up 48% of crash fatalities, up from about 25% in 2010. Finally, we know that the likelihood of a pedestrian dying in a crash has increased five-fold since 2010-2024. Less than 2% of pedestrian and/or cyclist-involved crashes resulted in death in 2010, nearly 10% of these VRUs struck in 2024 were killed.
| Who is a vulnerable road user (VRU)? The National Safety Council defines a VRU as “those unprotected by an outside shield.” In practice, this refers to road users outside enclosed motor vehicles. It includes pedestrians, cyclists, people on scooters, people in wheel chairs (motorized or otherwise), and sometimes motorcyclists. Trailnet’s report specifically focuses on “pedestrian” and “pedalcycle” crashes, as defined and reported by the Missouri Crash Analysis Reporting System (MOCARS). |
So what can we do? How do we confront the growing threat of traffic violence? While there is no proverbial silver bullet — no single solution to the problem — the evidence is clear on at least one fact: We need to slow down.
Speeding accounts for 11.9% of all crashes in the City of St. Louis and 13.5% of fatalities. In the City of St. Louis in 2023 (most recent data from the Missouri Crash Analysis Reporting System, MOCARS), 26 people were killed and 856 were injured in 1233 speeding related crashes. These rates are much higher than all other cities in Missouri except Kansas City. Speeding-involved crash rates and fatality rates are 3.3 times higher than Missouri’s third ranked cities in either category (Springfield and Independence, respectively).
The bottom line? Mobility is a right. No one should risk their life just to get where they’re going. Speeding is clearly a problem in St. Louis, and we need to do something about it.
The Root of the Problem: The 85th Percentile “Rule”
Researchers have long known that pedestrians are particularly vulnerable to high speeds. When a pedestrian is struck by a driver at 30 mph, they have a 45% chance of being killed. This figure drops to just 5% at 20 mph. It should be no surprise, then, that in a city like St. Louis — where most arterial speed limits are 30 and 35 mph — that we have a speeding-related traffic violence problem. So why are limits so high?
Image Credit: National Association of City Transportation Officials (2020) — City Limits
Currently, the practice of setting speed limits in the US is almost universally dictated by percentile-based method, typically set at the 85th percentile. St. Louis, and Missouri more broadly, are no exception (although no state law mandates the use of the 85th percentile to set speed limits). How this works is traffic engineers measure average vehicle speeds on roads, calculate the speed at which 85% of drivers travel at or below, then set speed limits by rounding to the nearest 5 mph increment. This, according to the National Association of City Transportation Officials (NACTO), is a system that is “designed to fail.” Why? “This method forces engineers to adjust speed limits to match observed driver behavior instead of bringing driver behavior in line with safety goals and the law” (NACTO, 2020, pp. 20). And NACTO isn’t alone in their critique of this engineering “best practice.” In its 2023 manual, Safe System Approach for Speed Management, the US Department of Transportation (USDOT) recognized that “the 85th percentile speed may not correspond to safe operations for every roadway context,” citing the fact that at normal speeds on arterial urban roads in particular (e.g., 35 mph), drivers tend to underestimate their speed by 30%. This is leading many US states to rethink their approach to speed limits. We need to set speed limits based on safety, not driver behavior.
Taking a New Approach: 25/20
While recognizing there is no single fix to end traffic violence, lowering speed limits in the City of St. Louis to 25 mph on arterial streets and 20 mph on local streets (a 25/20 approach) can be a critical part of a multi-pronged, broader approach to increasing roadway safety — especially for VRUs like pedestrians and cyclists. While evidence shows that other approaches, like traffic calming, complement speed limit reductions, a lower speed limit can — even on its own — be effective in reducing driver speeds and increasing safety. The National Highway Traffic Safety Administration (NHTSA) — the USDOT agency tasked with reducing deaths, injuries, and economic losses from motor vehicle crashes — recommends lowering speed limits on urban streets as a cheap and effective way to improve safety, stating “convincing evidence exists that lowering speed limits can reduce average travel speed and crashes in urban areas, even if no or few changes are made to the roadways.”
The 25/20 approach aligns with federal recommendations and evidence from other cities. The USDOT’s Safe System Approach for Speed Management suggests that 19 mph is the recommended “safe” speed for local urban streets, while evidence from Boston, New York, and Seattle show how lower limits on arterials reduce actual driving speeds as well as crashes.
In Boston, lowering the speed limit from 30 mph to 25 mph caused a 29% reduction in the likelihood that drivers would travel over 35 mph. Notably, this reduction in speeding occurred with no increased enforcement (Cicchino & Hu, 2020). Given that fatality rates for pedestrians dramatically increase as speed increases, this reduction is not only beneficial, but lifesaving. Similar results were seen in Seattle, where speed reduction to 25 mph on arterials and 20 mph on local streets were coupled with an increase in speed limit signs. With these improvements, drivers slowed down and crashes were significantly reduced Seattle Department of Transportation, 2022).
| City | Arterial Speed Limit | Implementation Date | NotableResults |
| Seattle, WA | 25 mph | 2016 | 22% reduction in total crashes, 18% reduction in injury crashes, 54.1% decrease in speeds over 40 mph |
| New York City, NY | 25 mph | 2014 | 35.8% reduction in crashes and 38.7% reduction in casualties (injuries + fatalities) on streets affected by the 25 mph change |
| Boston, MA | 25 mph | 2017 | Reductions of 2.9%, 8.5% and 29.3 % in the odds of vehicles exceeding 25 mph, 30 mph and 35 mph, respectively. |
As we work to make St. Louis a better, safer place to live, addressing high driving speeds is essential. With improved connectivity, a broad system of traffic calming improvements, and the use of equitably distributed automated enforcement, speed limit reduction is a necessary step toward ending serious injuries and fatalities on our roads.
Together, we can advocate to make this vision a reality. Now is the time to reach out to your local representatives in support of speed reduction in St. Louis City:
