Save lives by lowering the speed limit

12/4/2017

A recent report from the Ohio Highway Patrol has found a sharp increase in the number of crashes and fatalities after the state raised its top speed limit from 65 to 70 miles per hour. Not long after the release of that report, the same agency announced that 16 people had died on Ohio roads during Thanksgiving holiday travel.

This is the predictable result of raising speed limits. A raft of research shows that when speed limits go up, so do fatalities.

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A 2009 study published in the American Journal of Public Health estimates speed limit increases were responsible for 12,545 deaths and 36,583 injuries between 1995 and 2005. The number of rural interstate fatalities caused by higher speed limits jumped 9.1 percent during that time. An analysis led by Wayne State civil engineers found that fatality rates on roads with limits of 75 mph or higher are double those on interstates where limits are lower.

Higher speed limits come with a financial cost, too, and it involves much more than just replacing a few signs. State Departments of Transportation have to make road curves smoother and add crash pads to medians, for example, to make driving faster safer. Faster driving means maintenance costs go up, too. In 2014, researchers working with Michigan’s DOT found that upping rural interstate speed limits from 70 to 80 mph would save 15.4 million passenger vehicle hours a year, but would also cost $163.88 million annually for the design’s estimated 25-year lifespan.

And, of course, driving faster burns more fuel. That’s why Congress set the national speed limit at 55 mph in 1978. (It nixed the law in 1995, and returned the power to set limits to the states.) That same Michigan DOT report estimated raising freeway speeds would increase the state’s annual fuel consumption by 68.7 million gallons. That’s $257.5 million worth of gas and 1.3 billion pounds of carbon dioxide emissions. None of that factors in the costs of crashes themselves — $836 billion in 2010, according to the feds.

The emotional justification for raising speed limits is obvious to just about anyone who has driven on a highway — it seems like everybody speeds at some point, so how harmful could it be to just change the rules to reflect that? The data could not be clearer —quite harmful. Unfortunately, it seems Ohio state legislators have either failed to delve past their gut-level intuitions, or sought to score easy points with constituents who have not examined the issue in any detail either. 

Perhaps one could make a safety-versus-freedom argument in favor of raised speed limits. But now the Ohio Department of Transportation plans to increase the number of state troopers working in the areas worst-hit by the increase in crashes, so it is far from clear that Ohioans are freer for the extra five miles per hour. What is entirely clear is the price we pay for higher speed limits: 24 percent more crashes, 22 percent more fatal crashes, and hundreds of millions of our tax dollars.