In bumper-to-bumper traffic leaving Boston on Thursday evening, full-time Lyft driver Fabio says he timed the drive perfectly.

“Traffic is awesome,” says Fabio, who preferred to not give his last name, motioning to the gridlock around him in the Ted Williams Tunnel. “Rush hour is great.”

That sentiment stands in sharp contrast to promises made by founders of ride-hailing companies like Uber and Lyft to reduce traffic congestion and air pollution. Studies suggest these companies may actually be putting more vehicles on the road by shifting riders away from less energy-intensive forms of transportation – even enticing them to make trips they otherwise wouldn’t have made at all.

To truly become part of the solution, observers say, these companies need to revamp their business models to function within a broader transportation system. Currently, Fabio and his fellow drivers get paid by the minute and the mile, meaning they have a financial incentive to be on the road as much as possible.

Ride-hailing travel “is not a sustainable way to grow the city,” says Bruce Schaller, a former senior official in the New York City Department of Transportation who has authored several reports on the impact of app-based ride hailing. “But there are ways [companies like Lyft and Uber] can add to mobility and not have so many negative effects.”

For their part, Lyft and Uber envision ride-hailing apps as a catalyst for a future with fewer cars on the road. Both companies say one-person car trips dominated US travel before ride-hailing. By working with cities to integrate ride-hailing with public transportation networks and encouraging carpooling, they aim to ultimately reduce vehicle miles traveled.

“The goal should be to maximize movement of people while minimizing movement of cars,” says Adam Gromis, Uber’s global lead on sustainability and environmental impact. “That's what the whole conversation should be about for everybody.”

David Goldman/AP A sign directs Lyft and Uber riders to a designated pickup location at Hartsfield-Jackson Atlanta International Airport in Atlanta, Wednesday, Jan. 31, 2018. Ride-hailing companies are increasingly looking to partner with existing transit options to create a more integrated transportation system.

The myth and the reality

If a taxi is only one smartphone click away, argue Uber and Lyft, then travelers will be less inclined to own a car, and therefore spend less time driving. Less driving means less traffic and less greenhouse gases like CO2 in the atmosphere.

But there is “little difference” in vehicle ownership between ride-hailing users and the rest of the United States, says Regina Clewlow, a former research scientist at the University of California-Davis Institute of Transportation Studies, in an October report.

And in a more important tell for traffic and pollution, at least 50 percent of the trips Dr. Clewlow analyzed either would not have been taken without ride-hailing or would have been made by walking, biking, or taking public transit.

“People are traveling [in cars] more – there is induced demand,” says Clewlow. “If you make things cheaper and easier, there's more of it.”

Densely populated cities such as Boston, New York, and Los Angeles should be investing in other forms of vehicle management, say transportation planners like Clewlow and Mr. Schaller. It will take innovative concepts such as congestion pricing, high-occupancy carpools, and improved public transportation that can work in concert with ride-hailing apps.

Should cities add their own surge pricing?

In New York, since 2013, ride-hailing apps have added 976 million miles of new vehicle travel, according to Schaller’s most recent analysis. That’s the equivalent of 317,000 cars driving from Portland, Maine, to Los Angeles. And more than one third of those additional miles were driven in 2016 and 2017.

To alleviate congestion in Manhattan, Schaller, New York Gov. Andrew Cuomo, and others including Uber, favor a congestion pricing system that would charge vehicles to drive through congested areas during peak travel times, similar to schemes used in some European cities.

“There is a lot to learn from London and Stockholm, ranging from gaining public acceptance to the technology,” says Schaller. “They continue to be good examples to draw from.”

Stockholm has seen a 20 percent decrease in traffic through its city center and a 5 to 15 percent reduction in the city’s air pollution since levying a congestion tax in 2007. In London, road traffic decreased by 10 percent between 2000 and 2015 and by 21 percent in Central London specifically, despite the fact that its population continues to grow.

In New York, Governor Cuomo has pushed for a $11.52 surcharge for drivers using ride-hailing apps in a high-traffic zone in Midtown. He was unable to garner enough support in the legislature for inclusion of that measure in the state budget, which passed on Friday. But the new budget does include a $2.75 surcharge for every app-facilitated ride south of 96th Street, which Cuomo and his colleagues hailed as a step in the right direction.

What about pooling options?

America’s first carpooling system can be traced back to the early 1900s, when jitneys – private drivers looking to make extra money – started popping up in Los Angeles.

L.A. has since become the most congested city in the world, and Los Angelinos are once again seeking out carpools for hire, facilitated by UberPool and Lyft Line, newer features offered by the popular apps.

In its first eight months in Los Angeles, UberPool prevented 1.4 thousand metric tons of CO2 from entering the atmosphere, according to Uber’s Mr. Kalanick. That’s equivalent to taking nearly 450 cars off the road.

But critics say that app-directed carpools send drivers in unnecessary circles and entice riders to forgo mass transit in favor of inexpensive door-to-door service.

“[T]heir drivers roam all the time, much like taxis, and this adds to the road traffic,” says Daniela Rus, director of MIT’s Computer Science and Artificial Intelligence Laboratory.

To truly see benefits from UberPool and Lyft Line, the companies would need to go a step further with larger-scale pooling, Professor Rus and her colleagues suggest. One study found that 3,000 four-passenger cars could fill 98 percent of demand currently being filled by 13,000 New York City taxis.

Such a system would require optimizing the size and quantity of cars moving through the city at various points of the day, says Rus. “It requires a different approach to fleet management.”

Los Angeles is already thinking along these lines. In October, the Los Angeles County Metropolitan Transportation Authority asked the private sector to submit partnership proposals for a “MicroTransit Pilot Project”: a high-density carpool and public transportation hybrid.

Better public transit?

Like in L.A., traffic is a part of Boston’s history: street congestion in the late 1800s prompted Boston to build the country’s first subway system.

But 21st century commuters say traffic is only getting worse. Many of Boston’s traffic woes are fueled by a mixture of population growth, frustration with an aging public transit system, and the introduction of inexpensive cars for hire. A February study by the Metropolitan Area Planning Council found that 15 percent of ride-hailing trips add cars to Boston’s roadways during morning and afternoon rush hours.

As part of an ongoing effort to alleviate some of the traffic pressures on the city and to improve public transit options, Boston Mayor Marty Walsh on Tuesday allocated an additional $5 million to support capital investments included in the city's nascent Go Boston 2030 plan to reenvision Boston’s public transportation system. Over the next decade, the city hopes to reduce commute times by 10 percent and transportation’s greenhouse gas emissions by half of 2005 levels.

Reducing travel in single-occupancy vehicles is a core component of this plan, through initiatives such as pop-up carpools from Boston suburbs, dedicated bus lanes, and ride-hailing optimization for the “last mile connections” between homes, jobs, and public transportation.

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For now, drivers like Fabio are reaping the benefits of an aging and often unreliable public transit system. Before his phone signals the end of the current trip, another one queues up.

“Boston is a good city to do this in,” he says. “It’s nonstop.”