Ride sharing will, along with taxi cabs, become a more widely used mode of transportation than buses by the end of the year, and is making traffic worse to boot.

That's one of the surprising findings in a study from New York City's Bruce Schaller, who has focused his work on how companies like Uber and Lyft are changing the way Americans travel, and what that means for other ways of getting around. His report forecast an annual rate of 4.74 billion trips in for-hire vehicles by the end of 2018, 241 percent more than through the last six years. That will eclipse the predicted 4.66 billion rides on local buses, Schaller found.

Schaller's study supported previous findings that ride share is more likely to take the place of walking, biking, or taking public transit than a person using their own car. It also included some of the first findings on the economics of ride share users. In the biggest urban areas, ride share users are overwhelmingly well educated and wealthier, he found. That trend holds across smaller cities, suburbs, and rural areas, though less dramatically than in metropolitan centers.

A service favored by wealthier people that's hurting public transit raises concerns about transportation equity, said Chris Puchalsky, director of policy and special initiatives for Philadelphia's Office of Transportation and Infrastructure Systems.

"There is a long-term, possibly vicious, cycle here that has a negative consequence for those who really cannot afford to pay Uber and Lyft fares," he said. "And the city from a congestion point really cannot afford all this extra traffic."

Uber countered the notion that its customers are largely wealthier people. Schaller did find that the lowest economic rung, those earning less than $15,000 a year, used ride share almost as much as the very wealthy in smaller cities. In New York City, where data on ride share trips is public, Uber has become widely adopted in boroughs to reach public transportation, said Danielle Filson, a company spokeswoman.

"People are using this to get to transit centers where there isn't a lot of other options," she said.

She also noted Uber business is growing in areas where there's limited public transit, creating mobility for people who don't have access to cars.

Lyft said Schaller's findings aren't definitive, and other studies have come to different conclusions, including one that found traffic in the San Francisco Bay Area declined as Lyft ridership grew.

Schaller drew his data from numerous sources, including a recently concluded federal survey on travel habits and data culled from individual cities. He also wasn't entirely critical of the ride share industry. He noted its benefits in providing an option that can reduce drunk driving, and said ride share can be an important lifeline for senior citizens, low-income communities, and people with disabilities.

The affect of ride sharing businesses on bus ridership has been identified as a concern for SEPTA, which had 18 million fewer bus trips in 2017 than the year before. That decline is in part driving an effort to remake the city's bus service with more frequent, faster service. Schaller suggested in his report exactly the types of changes SEPTA envisions. His report offered policy prescriptions, but he also said it was one of the few studies conducted with the most current data available. The newness of ride sharing, an industry that didn't exist a decade ago, coupled with Uber and Lyft's reluctance to share data on their operations, has made it difficult to compile accurate information about exactly how they're affecting Americans' travel habits.

>> READ MORE: SEPTA's vision for a new bus network: faster, fewer stops, no transfer fees

"The [ride sharing companies] are running a business and they're attracting customers," Schaller said in an interview Wednesday. "We need public policy but we need the data to understand what is going on."

His study found that ride sharing was overwhelmingly reliant on urban areas for revenue. About 70 percent of Uber and Lyft trips nationwide happened in nine large metropolitan areas, one of which is Philadelphia. He also challenged those companies' claims that their pool services would play a role in reducing road congestion.

Schaller's report found that for every mile not traveled by an individual in a private vehicle because of ride share, an additional 2.6 miles is traveled by carpool-service vehicles. The increase is due to the time ride share vehicles spend traveling to pickup points and driving while waiting for a passenger.

"There's been this assumption that ride sharing would offset the traffic clogging effects of UberX and Lyft," Schaller said. "When you work through the numbers, that's not the case. You still get very substantial increases in traffic."

While the report didn't look at Philadelphia directly, the Washington, D.C., metro area was reviewed, and that region is comparable, Puchalsky said. Based on the Washington data, Puchalsky estimated ride share vehicles were adding 200 million extra miles traveled on Philadelphia's roads.

"In terms of the congestion-reducing impacts that transit has in carrying a lot of people in a small amount of space," he said, "these shared services really can't do that, can't do the role that transit plays."

There's a cycle transit experts believe ride share vehicles are perpetuating. It is drawing passengers away from public transit, reducing revenue brought in by bus fares. Meanwhile, as the roads fill with ride share vehicles, traffic worsens and bus travel becomes slower and less reliable, creating more frustrated riders who abandon buses for other options.

Schaller proposes policy solutions like congestion pricing, limiting low-occupancy vehicles in urban areas, or increasing trip fees. Filson noted Uber supports congestion pricing in New York City.

Philadelphia has no direct control over the ride share industry, which is regulated by legislation from Harrisburg and overseen in the city by the Philadelphia Parking Authority.