Do Uber and Lyft add to West Hollywood traffic?
Do transportation network companies (TNCs) such as Uber and Lyft add to traffic? We know they offer services that can help reduce traffic, such as carpooling and “first-mile-last-mile” links to transit lines. However, recent studies suggest that, on balance, TNCs add to the volume of traffic on city streets. They increase:
- The number of vehicle trips
- The number of vehicle miles per trip
- The total number of vehicle miles traveled (VMT)
This report assumes that those findings from other cities can be applied to West Hollywood.
Added vehicle trips
At least half of TNC trips are new vehicle trips, which add to traffic volumes. They are “new” in the sense that they wouldn’t have been vehicle trips if it weren’t for TNCs. The user would have taken transit, walked, or biked. In some cases, the user wouldn’t have made the trip at all if it weren’t for TNCs. That’s called “induced demand.”
The other half of TNC trips are replacement vehicle trips. The user would have taken a vehicle — such as their own car or a taxi — if TNCs weren’t available.
The chart below shows new-versus-replacement estimates from three user surveys. The new vehicle trips are red and orange. The replacement trips are green. In the San Francisco and Denver surveys, roughly half of TNC trips were new vehicle trips. In the third survey, the number was even higher. It was about 60%. That study covered Los Angeles, Boston, Chicago, New York, San Francisco, Seattle, and Washington, DC.
The bulk of new vehicle trips were shifted from transit, walking, and biking. For example, in San Francisco, 44% of TNC trips came from those modes. A third of all TNC trips were shifted from transit alone.
A smaller but significant number of TNC trips came from induced demand. TNC service was so appealing that users made extra trips they wouldn’t otherwise have made. Those trips are red in the chart. They ranged from 8% to 22% of TNC trips.
Added vehicle miles per trip
Even when a TNC trip replaces a private car trip, it still adds vehicle miles. The TNC driver may have to travel some distance to reach the rider. When the trip is over, the driver may need to drive to a different area to await the next job. It’s called “deadheading.” It means the average TNC trip is longer than the private car trip it replaces.
In the Denver study, deadheading increased trip mileage by 69%. In New York, about 50% of added VMT was due to deadheading. In San Francisco, deadheading added 25% to trip length.
Added vehicle miles traveled
How much do TNCs add to the miles driven by all vehicles in a city? TNCs added an estimated 7% to total VMT in Manhattan and nearby parts of Brooklyn and Queens from 2013 to 2016. The impact was smaller (2%) in the rest of the city.
7% increase in total vehicle miles in Manhattan due to TNCs
How big is a 7% increase in VMT? If New York City started charging cars to enter the busiest areas of Manhattan, it would reduce VMT by only 6%. So 7% is a significant increase in traffic.
Given the size of West Hollywood, a Manhattan neighborhood might be a better analogy than the whole borough. We wondered whether some neighborhoods experienced a bigger VMT impact. The chart below from the New York study shows TNC/taxi trip growth in selected neighborhoods. The growth rates range from 6% to 121%. It suggests the VMT impact could be much higher than 7% in some neighborhoods.
We also have VMT numbers for San Francisco. The numbers are only for vehicle trips from one part of the city to another, not trips entering or leaving the city. The numbers suggest TNCs were responsible for 20% of VMT on weekdays.
The San Francisco study doesn’t provide a new-versus-replacement breakdown. If we assume it was half-and-half, then TNCs added more than 3% to total VMT. How much more depends on data we don’t have.