Transit systems should be encouraged, rather than threatened, by the proliferation of transportation choices, according to a new report issued by the American Public Transportation Association. Released last week, the report determined that the people who depend most heavily on shared modes of transportation -- including ride-hailing apps like Uber and Lyft, bike sharing, and car-sharing services like ZipCar and Car2Go -- are also more likely to rely on public transit.

Researchers from the Shared-Use Mobility Center, using customer surveys in seven U.S. cities, found that public transit and other shared transportation modes usually did not compete for riders. Respondents generally relied on bus and rail service for their daily commutes and for running errands, and on ride-hailing services late at night and on weekends when public transit systems are either closed or offer limited services. Many of the respondents volunteered that they used ride-hailing services after drinking (peak usage times correspond to bar closing times).

In fact, people who rely on Uber or Lyft are most likely using them to replace other trips by car, researchers found. Thirty-four percent said they would drive alone or with a friend if the ride-hailing services were not available; another 24 percent said they would use car-sharing services as their backup. Just 14 percent said they'd ride a bus or train instead.

"People who use public transit and these shared services are making a lifestyle change that results in more walking, less driving and greater household savings because of overall lower transportation costs," said Valarie McCall, the board chair for the American Public Transportation Association.

Sharon Feigon, the executive director of the Shared-Use Mobility Center and principal investigator for the study, said one of the most encouraging findings was that people who used several transportation alternatives reported having fewer vehicles than other survey takers. That's good news for people who want to reduce the number of autos on the road, she said.

But not every income group had access to the same range of options. For example, respondents making less than $25,000 a year were three times more likely than other survey takers to say they would simply not travel if their first option wasn't available.

That led researchers to recommend that public transit agencies encourage greater use of the new transportation alternatives, particularly in places with poor transit service and for lower-income riders.

"The suburbanization of poverty has resulted in longer commutes, poorer job access and greater reliance on car ownership for many people who can least afford it," they noted.

Researchers also encouraged public transit agencies to consider other ways private ventures could improve their own services. One area that could benefit from those collaborations is paratransit. The transportation services that transit agencies offer disabled passengers is often slow, inefficient and expensive, researchers found. Transit agencies could use software similar to the technology that lets Bridj, a pop-up bus service, decide where to send buses or that allows Uber Pool customers to split rides, Feigon said.

Transit agencies could even use ride-sharing services as alternatives for paratransit. But one major impediment could prevent that from happening, the report noted: the drivers' status as independent contractors rather than employees. That could hamper transit agencies' ability to make sure drivers comply with federal drug-testing rules, have adequate liability insurance, accommodate wheelchairs and service animals, and undergo federally required vehicle inspections.

The researchers used online questionnaires to gather survey responses from 4,500 transit customers and users of sharing services in Austin, Boston, Chicago, Los Angeles, San Francisco, Seattle and Washington, D.C. The researchers plan to release a more in-depth report and data analysis about the findings within two months.