Uber and Lyft have long argued that ride-hailing apps have the potential to make cities better by easing traffic and reducing personal car ownership. And every time a study emerges that counters that narrative by exposing ride-hailing’s worsening effects on congestion, the two companies respond by casting doubt on the studies’ findings.

Well, this time the data is coming from inside the house. Uber and Lyft tapped transportation consultancy Fehr & Peers to examine their combined vehicle miles traveled (VMT) in six cities in September 2018, and compare that number to the total VMT in each area for the same month. The results show that while they are vastly out-stripped by personal and commercial vehicles, Uber and Lyft are still responsible for significant shares of VMT in those cities.

this time the data is coming from inside the house

The analysis looks at Boston, Chicago, Los Angeles, San Francisco, Seattle, and Washington, DC. The results are presented on two levels: the regional area, including the surrounding towns and suburbs, and the “core” county of each region that contains the main part of the city with the densest concentration of jobs.

The findings show that Uber and Lyft account for just 1-3 percent of VMT in the broader metropolitan areas of each city. But those numbers spike when zooming in on the core county of each city. In San Francisco County, for example, Uber and Lyft make up as much as 13.4 percent of all vehicle miles. In Boston, it’s 8 percent; in Washington, DC, it’s 7.2 percent.

These figures suggest that Uber and Lyft are hitting some cities harder than previously thought. An independent study commissioned by the San Francisco County Transportation Authority looked at 2017 traffic patterns in the county and concluded that TNCs generated about 6.5 percent of the total VMT on weekdays, and 10 percent on weekends. (TNC, which stands for transportation network company, is an industry term used to describe ride-hailing apps like Uber and Lyft.)

The findings from Fehr & Peers show totals “nearly twice that previous estimate,” said Gregory Erhardt, a professor of civil engineering at the University of Kentucky who has researched Uber and Lyft’s effects on public transit ridership. “This difference may be due to the continued increase in TNC use over the intervening two years.”

But some cities aren’t as hard hit as others. Uber and Lyft represent lower percentages of total VMTs in Chicago, LA, and Seattle. And New York City, the largest market for both companies in the US, was left out of the analysis altogether, likely because of the city’s low rate of car ownership and extensive public transportation network.

But some cities aren’t as hard hit as others

The study also examined the various phases of ride-hailing, from a driver with an empty car looking for a fare to one with a passenger on their way to a destination, and the effects on congestion. The memo shows that on average, just 54 to 62 percent of the vehicle miles traveled by Uber and Lyft vehicles were with a rider in the backseat; while a third of VMT occurs with no passenger in the vehicle, also known as deadheading. (New York City is trying to attack this problem of deadheading by passing laws tying driver wages to the amount of time they spend with a passenger in their vehicle.)

The ride-hailing companies are seizing on the distinction between their own VMT and the total for personal and commercial vehicles as a way to soften the blow. “The research shows that despite tremendous growth over the past decade, TNC use still pales in comparison to all other traffic,” Chris Pangilinan, Uber’s head of global policy for public transportation, writes in a blog post, “and although TNCs are likely contributing to an increase in congestion, its scale is dwarfed by that of private cars and commercial traffic.”

Lyft’s response to the city is even more positive in its spin. “We know that personal vehicles are the biggest factor, with 76 percent of Americans commuting alone to work,” Peter Day, head of policy and analysis at Lyft, writes. “But, we also need to know rideshare’s role as we continue striving to help solve challenges cities face.”

To be sure, Uber and Lyft have weathered criticism about pollution and traffic congestion for years. And the company has tried to address it through a variety of means, including its bike- and scooter-sharing services, its effort to integrate public transportation scheduling and ticketing into its app, and its incentive program to get drivers to switch to electric cars. Uber also supported New York City’s recent push for congestion pricing.

But the fact that there are more private cars than Uber and Lyft vehicles in any given city is not a revelation. The number of miles of added driving is the relevant statistic, and for once, it’s the ride-hailing companies’ own data that underscores this.

Transportation experts are mostly fed up. “As Uber & Lyft add to city traffic, lose $billions, and undermine transit, we need to ask ourselves what transportation problems they solve,” former New York City transportation commissioner Janette Sadik-Khan tweeted. “New data from TNCs show that they are convenient cabs, not the transportation revolution they promised.”