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By Chelsea WhyteUber and Lyft drivers are on strike to demand regulated fares and livable wages, in the lead-up to Uber’s initial public offering on the stock exchange on 10 May. Now there is some more bad news for these services: they haven’t lived up to claims of reducing traffic congestion.
In San Francisco, rides through these two services increased traffic delays by 40 per cent over a six-year period, according to a new study.
“We collected information on where and when exactly these trips occur and found they are at the most congested parts of the city and the most congested times of day,” says Greg Erhardt at the University of Kentucky.
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They first asked the companies for access to the data but were turned down. “The companies themselves are wholly disinterested in sharing data with anyone,” says Joe Castiglione at the San Francisco Transportation Authority, who also worked on the study.
Instead, the team scraped data from Uber and Lyft by simulating ride requests. This allowed them to map the position of drivers and to determine how many trips are taken, along with where they begin and end.
To find out the effect of these trips on traffic in the city, the team used a tool employed by transport planners that takes into account population growth, employment rates, construction of new roadways and public transit.
The model they used was calibrated to 2010, before Uber and Lyft were widely in use, which offered a chance to forecast into the future what traffic would have been like without these services and then compare it to real world data.
When they did that, they found that Uber and Lyft were the largest contributors to traffic in San Francisco between 2010 and 2016. The added cars on the road and the disruption of traffic from curbside pick-up and drop-off increased the total vehicle hours of delay in the city by 62 per cent.
Without Uber and Lyft in the simulation, that delay grew by only 22 per cent, meaning that the services accounted for 40 per cent of the increase, says the team.
That congestion affected average speeds, which were three times slower than they would have been without the added traffic. They also found that about two-thirds of Uber and Lyft cars would not be on the road if they weren’t part of the service.
Erhardt says these findings are based on San Francisco and may not apply directly to other cities, as there are so many factors to consider in each place.
Farzad Alemi at the University of California, Davis says these findings are valid, but cautions that the size of the effect suggests that there is more to be considered.
“The authors did not take into account the vehicle occupancy,” he says, adding that his own work found that the number of people per car increases on the weekends and in the evenings. But he says that we need more research to understand if those trips are replacing rides on mass transit or people driving their own cars.
“The study in question overlooks notable contributors to congestion including increased freight and commercial deliveries, and tourism growth,” says Lyft spokesperson Alex Rafter.
A spokesperson for Uber says, “While studies disagree on causes for congestion, almost everyone agrees on the solution. We need tools that help ensure sustainable travel modes like public transportation are prioritized over single occupant vehicles.”
Journal reference: Science Advances, DOI: 10.1126/sciadv.aau2670
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