Do Uber, Lyft and other ride-hailing services really help ease traffic congestion?

Have you heard that Uber and Lyft are helping alleviate traffic congestion by getting us to give up our personal cars?

That reassuring notion, nurtured by the ride-hailing services, gets repeated often. I've heard various forms of the bromide three times this summer.

The reality: They haven't relieved congestion and probably won't, at least not anytime soon, according to transit consultant Bruce Schaller's provocative report released last month.

Despite the popular narrative, Uber, Lyft and their smaller competitors haven't prompted many people to give up their vehicles, Schaller found. And they've actually made congestion worse by driving billions of additional miles on the nation's roads each year.

The explanation starts with the logistics of modern ride hailing. A trip in a personal vehicle requires driving to the destination. In contrast, ride-hailing services first have to drive to passengers' location before taking them to where they want to go. Those "empty" miles add up.

Another factor: The ride-hailing companies appear to be drawing passengers away from transit.

If Uber and Lyft weren't available, about 20 percent of passengers said they would have taken their own car, Schaller found, and another 20 percent would have taken a taxi. Both situations are more or less a wash for congestion, swapping one car for another.

"The results clearly show that instead of 'replacing the personal auto,' (the companies) in large cities are primarily supplanting more space-efficient modes such as bus, subway, biking and walking," Schaller wrote in "The New Automobility: Lyft, Uber and the Future of American Cities." "The net result is more driving mileage and less use of public transit."

Since 2012, the new companies have more than doubled the size of the nation's ride-hailing sector, Schaller said. They make up the majority of for-hire rides, carrying 2.61 billion passengers in 2017 compared with 730 million for taxis.

Passenger counts are projected to reach 4.2 billion this year. That's approaching the 4.8 billion passengers who rode buses last year.

As the numbers increase, services like UberPool, where passengers share rides, won't help much, Schaller added. They only result in "marginally lower mileage increases."

He also found that "remarkably few" passengers used the ride-hailing services to connect with transit options including buses and trains. Another recent study, paid for by Uber, showed that only 6 percent of its passengers in Florida used the service in conjunction with transit.

Unless we collectively embrace carpooling with strangers, autonomous vehicles might not provide much relief, either, Schaller said. So far, we've gravitated to one-person transport, whether it be driving our own cars or making trips alone using ride-hailing companies.

"Without public policy intervention, the likelihood is that the autonomous future mirrors today's reality: more automobility, more traffic, less transit, and less equity and environmental sustainability," he wrote.

Uber and Lyft have pushed back against Schaller's findings, especially his look at pooled rides. Uber referred to his analysis as "fundamentally flawed," adding that UberPool had saved "230 million miles" of driving globally. Lyft said more than 230,000 of its passengers gave up personal cars because ride shares were available.

Writing in CityLab, Robin Chase, co-founder and former CEO of the car-sharing service Zipcar, argued that ride-hailing services should not be blamed for congestion, given that they make up a small fraction of all the miles driven on our roads.

"Cities have been congested and transit has been poorly used for years before these companies set up shop," she wrote. " … What we need is not demonizing of ride-hailing services for 'new' traffic problems but fair user fees across all modes to encourage more efficient use of our streets."

Even with the caveats, Schaller's report is a good reminder to question assumptions about the various components of our transportation network.