AUBURN, Maine — The Maine Turnpike Authority is looking for a few good buses.

The agency has released an open letter to bus operators and other transportation companies to gauge interest in adding stops to Exit 75 here and the transportation center in Wells. Both exits have underused, MTA-owned property around the interchanges and residents have shown interest in park-and-ride opportunities, according to Sara Devlin, MTA planner and agency liaison.

“There has been a desire over the years to have some sort of service in the Auburn area, as well as the Wells area. We just thought it would be an opportune time to open this up,” Devlin said. “We wanted to find out what the interest is out there, if any.”

She described any potential development as “like a mini-public/private partnership.” It could involve new buildings, more parking spaces and a long-term lease.

The MTA has phrased it as a call for “Letters of Interest.” Depending upon the response, a request for proposals may follow. Devlin wasn’t aware of the turnpike taking the open-letter approach before.

“We just wanted to make this as transparent as possible, make sure that as many entities know about it and can respond to it as want to,” she said.

The park-and-ride lot outside the Auburn exit is undeveloped except for 137 parking spaces. According to a Department of Transportation and MTA study, about half of those, 72, are occupied on a daily basis.

The Wells site has 196 spaces and a rail terminal.

“I think the interest lies in going from the Lewiston-Auburn area to points south, mostly,” Devlin sud. “We would want to maintain the existing number of parking spaces for commuter service. One opportunity might be additional parking for people to hop on a bus … for long-term parking.”

In Augusta, that park-and-ride has a Concord Trailways terminal with a bus shelter, restrooms and a set schedule. Some riders use it to commute to Boston daily, she said.

Only one bus company has so far informally expressed interest to the MTA. Responses are due by Aug. 2.

After that, “we could either go into some negotiations with one company or we could say none of these really fit with what we think we’re looking for,” Devlin said. “We don’t want to do something just to do it; we want to make sure that it’s going to work for the region, the municipalities, the turnpike, the business, all entities involved.”

The timing of any projects would likely be dictated by the permitting process, she said.

Auburn City Manager Clint Deschene said he’s excited at the idea of improving transportation options in the area.

“I can’t wait to see what they come up with,” he said.

Auburn Mayor Jonathan LaBonte said the development would tie in with the broader effort to improve connections among Auburn, Lewiston and Portland, and with Auburn building a new transportation center on Spring Street later this year. One potential he sees: connecting downtown to the interstate with a bus that serves both.

“We’ve continued conversations with the turnpike and with Maine DOT on how we can work with private bus operators to make some of these things happen,” LaBonte said. “How do we get the private bus operators at the table? The turnpike’s letter of interest is part of opening that door.”