Ride-sharing services have boomed in many urban areas. Researchers are debating their costs and benefits.

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Is ride-sharing killing people? Yes, study suggests, but critics are doubtful

Has the boom in ride-sharing services such as Uber and Lyft led to an increase in traffic deaths in U.S. cities?

That is the provocative question a trio of economists tackles in a recent study. It concludes that the arrival of ride-sharing was associated with a 2% to 3% increase in the number of car occupants and pedestrians killed in accidents between 2011 and 2016.

Some researchers are skeptical of the finding, however, and say other factors might be involved. And ride-sharing companies are bashing the study, calling it flawed.

The United States has experienced a dramatic decline in the rate of fatal traffic accidents since the 1980s, economists John Barrios of The University of Chicago in Illinois and Yael Hochberg and Livia Yi of Rice University in Houston, Texas, note in a preprint posted online. In 2010, traffic fatalities dropped to 32,885, the lowest number since the late 1940s. But the decline halted, and then reversed, around 2014 – just when ride-sharing services started to gain a foothold in many U.S. cities.

To see whether there might be a relationship, the researchers compared accident figures compiled by the National Highway Traffic Safety Administration with data from Uber and Lyft on when they launched their services across 2955 cities and communities. They also looked at how much gas drivers in those areas consumed, how many miles they drove, how much time they spent in traffic, and how many new cars they registered.

In general, they found that after ride-sharing launched in a city, fatal accidents rose—and so did gas consumption, miles driven, time spent in traffic, and the number of newly registered cars. The accident increases were most concentrated “in large cities (high population), and more impoverished cities (as measured by per capita income),” they write, as well as cities with relatively high use of public transportation. One scenario that could explain the correlations, they suggest, is that as people shifted from public transit to ride-sharing services, more drivers became ride-share entrepreneurs—and then began to have fatal accidents on clogged roads.

The researchers are careful to note that “our documented effects alone are unlikely to fully explain the reversal of accident rate trends in recent years,” and that ride-sharing can have benefits, including providing more transit options for consumers and flexible work for drivers. But “the annual cost in human lives is non-trivial,” they write, and their results “point to the need for further research and debate about the overall cost-benefit tradeoff of ridesharing.”

Critics of the study say it doesn’t address some important issues. One is the possible role of low gas prices, which tend to lead to an increase in driving, notes economist Joe Cortright of Impresa, a consulting firm based in Portland, Oregon. Gas prices fell precipitously in late 2014, just as accident rates were ticking up, he notes on CityCommentary, a website run by the think tank City Observatory, also in Portland. He also notes that rural areas, which generally lack ride-sharing, saw an even larger increase in crash rates than the studied cities.

Lyft and Uber expressed skepticism about the study’s methods. And they argued that their services have increased safety—such as by reducing drunken driving. In a statement, Uber said, “We take our responsibility to help keep people safe seriously.”