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Bike Walk Life

News and commentary from the world of biking and walking.

Do Uber and Lyft reduce traffic? According to a new study, they do the opposite.

There has been a lot of optimism over how how rideshare companies could help save our congested streets. The very name, ride share, suggests that they create more communal, fair, and efficient relationships with car travel. But that hasn’t been the case. In fact, traffic and fuel efficiency has gotten worse according to a new study.

“Can sharing a ride make for less traffic? Evidence from Uber and Lyft and implications for cities” by Bruce Schaller [pdf] examines how ridesharing affects vehicle miles travelled (VMT) in different US cities. The paper goes into a lot of detail, but its key finding seems to be this:

Taking into account three key inputs – pooling rates, modal shifts and deadhead miles – results show that pre-pandemic levels of pooling led to at least a doubling of VMT when comparing ride-hail trips with patrons’ previous mode, with increases of 97% in Chicago, 114% in New York City, 118% in San Francisco, 157% in Boston and 118% in California suburbs.

That means that in the best-case scenario studied, miles doubled for people who switched to using rideshares instead of their personal vehicles. Most of the time, it more than doubled.

This seems nuts, and nowhere near sustainable.

Schaller calculated these numbers by including what he dubs “deadhead” miles. These are miles that the driver covers before picking you up, or covers between dropping you off and picking up the next passenger. So when you ride in an Uber or Lyft for 5 miles, you’re probably adding more than 10 miles traveled to the road.

His data also shows that ridesharing attracts more than car drivers. It draws in people from public transportation, biking, and walking, which also contributes to the overall increase of vehicle miles.

The study spends a lot of time with the optimistic hypothesis that ridesharing could reduce VMT if enough people pooled their rides. (Shaller notes that this would make the rides look less like taxis and more like public transportation.) Although this has not happened in practice, he presents a scenario where it would be possible:

a) 85% of trips are pooled (versus zero percent in suburbs and 16–20% in most cities pre-pandemic).

b) Most pooled trips are primarily with three passengers (versus most with two passengers pre-pandemic).

c) 70% of ride-hail patrons shift from auto or taxi (versus one-half or less pre-pandemic).

d) Deadheading drops to 20% of all mileage (versus 35–49% pre- pandemic).

e) Non-shared mileage of pooled trips (e.g., before the second passenger is picked up) is reduced to 20% of pooled passenger miles (versus 48% pre-pandemic).

And he immediately follows-up that scenario with this sentence:

It is difficult to see how these benchmarks could be attained, and particularly daunting to envision them in combination.

I have to say that I’m in agreement.

What does this all “mean?” For one, I think it’s time to be realistic about what Uber and Lyft are doing. Whatever benefits they bring, both real and theoretical, need to be compared alongside their very real impact on our towns. In another recent study, we saw that ridesharing also increases car ownership in cities. Is this a direction we want to go?

Second, this isn’t just about Uber and Lyft. They may be exacerbating the problems in a car-centric system, but the pre-Uber status-quo suffered from most of the same issues. One overarching problem is the way our system hides the costs of car travel from drivers. Maintaining car-oriented places is expensive for communities as a whole, but drivers are generally unaware of their impact as individuals. This VMT increase for ridesharing seems like just another level of that, a situation where riders are unknowingly creating congestion that they themselves never directly witness. We need environments where the cost of the choices we make, walking vs biking vs driving, are visible and obvious to us.

What’s the solution? In the words of Schaller:

Particularly in dense urban areas, space-efficient modes like public transportation, walking and biking must take the front seat in policy-making, with space for ride-hail and personal autos of lower priority.

I would add that walking and biking should take the front seat in every community, not just dense urban areas. Their benefits extend beyond their space-efficiency.