According to research conducted by the San Francisco County Transportation Authority (SFCTA) and an engineer from the University of Kentucky, ride-hailing companies Uber and Lyft are contributing to an increase in San Francisco traffic congestion despite both companies' earlier claims to the contrary.

Looking at traffic data between 2010 — namely, the days before ride-hailing companies began to dominate major U.S. cities — and 2016 — when the companies became transportation giants — SFCTA and Gregory Erhardt, a civil engineering professor at the University of Kentucky, determined that traffic congestion in San Francisco had increased by 60%. According to the research, much of that increase is attributable to the ride-hailing companies, despite both companies' claims that they reduce personal car ownership, thereby alleviating traffic.

In the absence of data from Uber and Lyft, who reportedly withhold such details to maintain a competitive edge over rival companies, researchers set out to present a “before” and “after” picture of traffic congestion with data taken directly from the ride-hailing apps. Researchers approached data scientists at Northeastern University who had constructed a computer program that queries the API (application programming interface) for both Uber and Lyft, and monitors the location of the 10 nearest vehicles on both apps.

“And what they were able to do is set up sort of a grid of client calls to the API across San Francisco for a six month period in late 2016,” Erhardt said. “Every two seconds, they say, ‘Hey, where are the 10 closest vehicles, write that to a database. And we ended up with about 17 terabytes worth of data. But what you get out of it are these traces of where the vehicles are, where the drivers are, and when they’re available for a ride.”

The model revealed that roughly two-thirds of the ride-hailing cars currently on the road in San Francisco are new vehicles that would otherwise not be there were it not for the ride-hailing companies. As such, the researchers suggest that in the absence of ride-hailing vehicles, the majority of passengers would have instead opted for public transportation over personal car use. Likewise, the researchers believe that instead of the 60% increase in traffic congestion, only a 22% increase in traffic congestion would have been experienced in the absence of ride-hailing vehicles due to factors such as construction and population growth.

Although the study concerned data exclusive to San Francisco, researchers believe that an increase in traffic is likely being felt wherever ride-hailing companies operate.

The study was published in the journal Science Advances.