Study Shows That Cannabis Legalization May Reduce Heavy Truck Crash Rates, Here's Why

A recent study conducted at state Universities of Tennessee, Arkansas and Iowa showed that U.S. recreational cannabis legalization reduced the number of heavy truck accidents by 11% in the eight states studied.

The researchers looked at a state-level panel of heavy truck accident statistics from 2005 to 2019 and a difference-indifference estimation strategy. "To test these hypotheses, we take a difference-in-difference (DID) approach, an empirical strategy that is well-established within empirical logistics research," the study read.

“We’re not saying definitively that legalization will reduce trucking accidents, but there is some evidence that legalization across the board doesn’t necessarily increase accidents,” said Jonathan Phares, one of the researchers and assistant professor at Iowa State University. “There are reasons why accidents could decrease as a result of legalization.”

In fact, the results showed that legalization did not increase average crash rates in the three states examined - Arkansas, Iowa, and Tennessee among others where recreational marijuana is legal.

"Six of the eight states examined saw a decrease in truck accidents and two saw increases. Vermont and Washington saw the most profound decreases, at -21.5% and -20.1%, respectively, followed by Colorado and Massachusetts, at -18.3% and -18% respectively, and finally Oregon and California, at -3.7% and -3.2%, respectively. The two states reporting increases were Maine at 4.18% and Nevada at 25.6%," according to the study.

While the researchers did not provide a solid explanation for why legal marijuana reduced crashes, they offered some theories.

"Those who would normally drink alcohol may have switched to marijuana. Research suggests that driving while high is far less likely to cause a fatal accident than driving while drunk. (...) Marijuana is usually consumed at home, not at a bar or restaurant," said Ron Gordon of the University of Arkansas.

Cannabis Decriminalization And Trucking Industry

Last year, the American Transportation Research Institute's (ATRI) board of directors approved their 2021 Top Research Priorities and cannabis was on the list.

“As we see more states decriminalize, the likelihood that we’re going to be sharing the road with car drivers who are impaired increases. The roadways are our workplace. So we want those roadways to be safe, and we want the drivers of trucks and cars to be free from impairment,” said Rebecca Brewster, president, and CEO of ATRI.
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