Q&A of the Day – Does the Amount of Traffic Impact Fatal Accidents?
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Today’s Entry: @brianmuddradio Does the amount of traffic increase/decrease fatal accidents? I remember hearing they were up during lockdowns.
Bottom Line: The harder the crash the worse it is right? It is logical that if people can go faster, they’d theoretically been prone to worse outcomes including potentially fatal ones. Today’s note isn’t randomly morbid. It’s on the back of my note yesterday that three Florida roads, including two in South Florida, having been identified as being among the 17 most deadly in the country in a Find By Plate study, including South Florida having the deadliest overall. Here’s a quick recap...
- I-95 from Palm Beach County through Miami-Dade is currently the 17th most deadly road
- Central Florida’s I-4 is currently 3rd
- US 1 throughout South Florida through the Keys is currently the deadliest
Before getting into the nitty-gritty of this stuff you might already be able to infer that the ability to speed alone isn’t the deciding factor. US 1 has the lowest average speed and fewest lanes of the three and it’s been the deadliest on a rate basis over the past year. I’ll come back to that in a moment. But first let’s look at what you referenced about what happened during the lockdowns.
The National Highway Traffic Safety Administration is the official tracker of all of this stuff releasing annual reports of what happened the year before each May. Because we’re not there yet, the most recent data we have is from 2021. But still, that works to give us a view of what happened during the peak of the pandemic when lockdowns were the norm and what happened the year after when most of the country was back to some semblance of normality.
After three straight years in declines in fatal accidents, from 2017-2019, 2020 – the peak of the pandemic did in fact see a huge increase in traffic fatalities. Population adjusted fatalities rose 7.1% year-over-year. That was the 2nd largest annual increase in traffic fatalities in over 50 years. As someone who came to work every day same as always during that year, I can attest to witnessing an increase in reckless driving behavior, especially on I-95, all times of the day. Fewer vehicles on the road and far more deadly crashes, that would seem to confirm the assumption that higher speeds, even with less traffic, is a deadlier combination. But then came the next year.
In 2021, there was a staggering 10.5% increase in traffic fatalities – with a total of 42,915 deaths during the year. It was the highest total number of deaths on the road since 2005. It was the largest one-year increase in the rate of traffic deaths since 1946 – when American men were just starting to drive again, and in many cases for the first time, after having returned from World War II. That would seem to mitigate the thought the opportunity to travel at faster speeds alone with less traffic on the roads would be the biggest factor. So, what happened, why is this the case and why is US 1 now the deadliest road?
The first key cog in the puzzle is breaking out traffic fatalities involving crashes between vehicles and fatalities involving pedestrians. Here’s the odds of a car crash between cars resulting in serious injuries or death based on speed:
- >50 mph: 1%
- 50-70 mph: 69%
- 70 mph+: 90%+
So yes, there’s empirical evidence that traveling at speeds of greater than 50 miles per hour is almost always required for there to be a fatal crash between vehicles. However, once accidents are occurring above 70 miles per hour, there’s little difference in outcomes. Almost all of those wrecks cause serious injuries and/or death. In that context, it illustrates that the most opportune situations for deadly vehicle crashes aren’t when traffic is lighter but with some cars aggressively speeding. The riskiest conditions are when traffic is heavy but is moving up to speed on highways. Hence much of what we saw in 2021. And that takes us to the rest of the story. Accidents involving pedestrians.
As you might imagine humans don’t hold up as well as vehicles in collusions. Because almost all collusions with pedestrians result in serious injury, here’s the speed breakout for collusions with pedestrians resulting in death:
- >20 MPH: 5%
- 35 MPH: 45%
- 60: MPH: 99%+
It doesn’t take a lot of speed to create fatal outcomes for people who’re struck by vehicles. And this is where the story comes full circle with today’s note but also why US 1 in South Florida has taken the top spot as the deadliest stretch of road. Think about how much foot traffic there is in and around US 1 in our area and all of the way down to Key West. Nope, cars aren’t going nearly as fast as on 95, but nope they don’t need to. Cars commonly do reach speeds on US 1 where collisions with pedestrians are usually fatal. So, in addition to this being informational, perhaps it’s a little extra food for thought regarding thoughtfulness when we’re driving proximity to people generally.