The massive popularity of ridesharing apps like Uber and Lyft have definitely made it more convenient to find a ride in any city, but they’re also making traffic worse, according to a new report from Schaller Consulting.

In the report, The New Automobility: Lyft, Uber and the Future of American Cities, author Bruce Schaller writes that these transportation network companies (TNCs) actually don’t cut down on personal car use or ownership. Instead, the report says, users mostly turns to TNCs so they don’t have to find parking when they go out, or so they don’t have to worry about drinking and driving.

The shared ride carpooling services (e.g. UberPOOL, Uber Express POOL, and Lyft Shared Rides) from TNCs are also making traffic worse, which could be impacting work commutes. According to the report, this is because they don’t take away from the added traffic of the normal ridesharing products, and are often not used as intended.

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“Shared rides add to traffic because most users switch from non-auto modes,” the report said. “In addition, there is added mileage between trips as drivers wait for the next dispatch and then drive to a pick-up location. Finally, in even a shared ride, some of the trip involves just one passenger (e.g., between the first and second pick-up).”

The key statement there is “non-auto modes.” According to the report, 60% of TNC users in “large, dense cities” would have just taken public transportation, biked, or walked if they didn’t have access to the services. The remaining 40% would have taken their personal car or a traditional taxi.

For the report, Schaller looked at data from New York, Los Angeles, Chicago, Boston, Washington, Miami, Philadelphia, San Francisco, and Seattle. TNCs added 5.7 billion miles of driving in these areas, the report found.

In the report, which can be found in PDF form here, Schaller notes that TNCs can be used in complement with public transit options, and outlines a host of policy changes that can help cities better accommodate changes in transit.

As noted in a Washington Post article about the report, both Lyft and Uber rejected the claims made by Schaller in his report. However, Uber did agree with Schaller on some of the policies he proposed in the report to lessen the impact of TNCs.

The big takeaways for tech leaders:

  • Ridesharing and carpooling services from Uber and Lyft are making traffic worse in major cities, which could worsen some commutes, according to a report from Schaller Consulting.
  • Most ridesharing apps attract people that would have otherwise simply walked, biked, or taken public transit, which adds to traffic.