Pat Chan finished shopping at the Eden Prairie Center on a recent Tuesday and needed a way to get back home. So he used his smartphone and arranged a ride.

Minutes later, a SouthWest Transit city bus pulled up and Chan hopped on. A transfer later he was back home in Chaska.

With its service called Prime, SouthWest Transit is pioneering Uber-style door-to-door on-demand rides, offering freedom of mobility and schedule flexibility not generally associated with traditional public transportation.

"SouthWest Transit is definitely forward thinking, and this is where things are headed when it comes to mobility," said Darnell Grisby, director of Policy Development and Research for the Washington, D.C.-based American Public Transportation Association. "Now the transit user can be as spontaneous as the auto user has been in the past."

Studies have shown that people are less likely to use public transportation if they are more than a mile from the nearest transit station or bus stop. SouthWest Transit launched Prime in July 2015 with the idea of helping passengers complete the "last mile commute."

Over time, Southwest has expanded its fleet of 12-passenger vans from three to 11 as the service has caught on. In August more than 5,300 riders used the service and since then monthly ridership has continued to top 4,200 people — students, seniors and those who don't own a car or choose to leave the one they own in park. They've used the service to get from their front door to work, doctor's appointments, shopping and social engagements, paying just $3 a ride with cash or a credit card.

"It has just exploded," said SouthWest Transit CEO Len Simich. "The general public has really taken to it."

Yvette Ventura, 65, of Eden Prairie, has. With no car, she is a regular rider, using the service for shopping, appointments and to get to her job at Target. "It's not expensive. It's convenient, especially with bad weather."

It took 20 minutes on a recent Tuesday and a few stops to pick up other passengers along the way for Rama Vibushnan to get to her job at Optum. She rides almost daily and said without Prime, she would not use public transportation.

Josh Phillips has used Prime for the past few months and called the service a "lifeline." Though he has a car or could walk the mile or so to get his daughter, Laree, 1, to New Horizon Child Care, he said the bus is "really convenient," especially on snowy January days. He is a frequent user of Prime for other purposes, too, he said as he took the bus back home after dropping his daughter off.

"I've never seen public transportation like this," he said.

For 30 years, SouthWest Transit, has provided weekday express service between Eden Prairie, Chanhassen, Chaska and Victoria and downtown Minneapolis, the Brooklyn Park Target campus and Normandale Community College in Bloomington. The agency had struggled to provide local service despite requests for it. It tried a circular fixed route, but ridership languished. In the 1990s, it offered Dial-A-Ride. With that, passengers had to book trips two or three days in advance, and in addition to being expensive to operate the service was plagued with a high rate of no shows and last-minute cancellations, Simich said.

Those problems have largely been absent with Prime. Riders who request a Prime ride but don't show up or don't cancel are charged the fare and can't book another ride until they pay. "That way we don't get stung by people who are booking and doing the no-show thing," he said.

A majority of Prime users don't have cars, said driver C.J. O'Hara, who for the past year has shuttled students to high school, seniors to the grocery store and appointments, and regular riders to work. When a drop off is complete, she waits in parking lots for the next request to pop up on her in-vehicle screen. It normally doesn't take long.

"It's challenging to keep up with the rides," she said. "For some, this is the only way to get around and I feel like their personal taxi. I feel good knowing I am helping these people."

Passengers use an app on their smartphones or call the agency's dispatch center to request a ride. The nearest bus is sent to pick them up. Riders get a phone call when their bus arrives at the pickup point. Once on board, buses may pick up other riders while en route to a passenger's destination, meaning just like with traditional public transit, passengers won't always have a private ride. Vibushnan's van had five riders by the time it reached Optum. Chan traveled solo.

SouthWest Transit's Prime operates from 6:30 a.m. to 6:30 p.m. on weekdays. Due to its popularity, the agency said it is looking at developing a partnership with Lyft to provide transportation on nights and weekends.

From January through October, SouthWest spent about $390,000 to operate the service, which provided just under 45,000 rides. The $3 fares collected covered 26 percent of overall costs. That is on par with the fare box recovery rate of its fixed-route services and that of many transit agencies around the country. The smaller vans help keep costs down as they are cheaper to operate than its express motor coaches.

Southwest Prime is at the forefront of the nascent business as commuters across the country look for pragmatic and cost-effective routes for every trip. Transit services in places such as Kansas City and suburban Oakland have launched or are piloting similar services or partnering with ride-sharing companies such as Uber, Lyft and Bridge to fill gaps that traditional service cannot reach. Other systems such as those in Los Angeles and Dallas are exploring options, Grisby said.

Last year, the Pinellas Suncoast Transit Authority (PSTA) in Florida launched its Direct Connect program in areas without transit service. The agency pays up to $5 for riders to use Uber to take trips that must start or end at a bus stop. It's been so successful that PSTA is expanding the on-demand service all across Pinellas County on Jan. 19, said spokeswoman Ashlie Handy.

Metro Transit does not offer such a service, and neither does the Minnesota Valley Transit Authority, which serves communities south of the Minnesota River. But it's on the radars of both, although funding is an issue.

Metro Transit is considering a "first- and last-mile pilot project" later in the year and is consulting with SouthWest Transit about their service, said spokesman Howie Padilla, though he declined to offer details. The agency's focus right now, he said, is "connecting people with suburban job centers that currently don't have regular route service."

Still services like Prime are crucial as cities and transit agencies experiment with new ways to serve customers, Grisby said.

"This is like a laboratory; there will be some successes and failures, but the movement to make transportation spontaneous is going in the right direction," he said. "We are going to see dramatic approaches in the coming years."

Tim Harlow • 612-673-7768