PORTLAND — A resurrected train line between downtown Portland and the Auburn-Lewiston Municipal Airport would do wonders for the state and all of the communities on the line, according to speakers at a forum in Lewiston on Friday.

Now it’s up to the state and those communities — Portland, Falmouth, Yarmouth, New Gloucester and Lewiston-Auburn — to really make it happen.

“In those five sites, for a three-quarter mile radius around them, there are $2 billion worth of property tax assessment,” Tony Donovan of the Maine Rail Transit Coalition said. “If we came in and increased those values by 7 percent, that would give these five municipalities an additional $3 million in property tax revenues every year.”

Donovan was one of the speakers at a Smart Growth Mobility Forum at the University of Southern Maine.

He was joined by others from the federal Environmental Protection Agency’s office of Sustainable Communities and LOCUS and real estate developers and investors affiliated with Smart Growth America to talk about encouraging economic development with transit development.

But the forum really centered on the St. Lawrence and Atlantic rail line, running from India Street in Portland through Falmouth, downtown Yarmouth, New Gloucester and ending in Auburn. It’s time to develop it, speakers said, and open up development of the track beyond.

“The St. Lawrence and Atlantic Railway, which goes from Auburn to Montreal, Canada goes from there,” Donovan said. “Bethel is on that line. Oxford Casino is on that line. Gilead, a little town just before the New Hampshire border, is on that line. We could walk down to India Street with our bicycle or hiking gear, board a train and enter the White Mountain National Forest right from the center of Portland.”

The Maine Rail Transit Coalition began studying the feasibility of refurbishing the 29-mile St. Lawrence and Atlantic public transit line between India Street in Portland and the Auburn-Lewiston Municipal Airport in August.

They released their 90-page report last week.

According to the report, the service could run 44 round trips per day between Auburn and Portland with an average 35 riders per trip. With $8 fares, that would generate about $4.9 million in revenues.

Donovan said the entire project would cost about $118 million based on estimates from the 2011 Portland North study. That includes reconstruction of the rail line from India Street in Portland to the Auburn-Lewiston Regional Airport with signals, safety crossings, underpasses and overpasses along the way.

By comparison, Portland’s Veterans Memorial Bridge project cost nearly $90 million, and work on the bridge between Kittery and Portsmouth, N.H., is in the same range, Donovan said.

“I’m not saying we should just drop $100 million here and there, but when it comes to transportation investments of that size, this isn’t a big number,” Donovan said. “Especially if you can show that there is a return on that investment and it reduces the cost of transportation for households and businesses.”

Lee Sobel, finance specialist with the U.S. Environmental Protection Agency’s Office of Sustainability, said federal grants, local tax incentives and private investment could pay for much of the work.

“The question is how much will this cost you if you don’t do it?” Sobel said. “How much will it cost in terms of economic job loss, in terms of revenue that would be generated, in terms of property value that meets up with growth that coalesces around transit projects?”

The rail project would show a return, according to Christopher Coes, managing director for LOCUS. Communities that build train stations see the surrounding land become more valuable because people will go there. Adding attractions makes it place people want to be, he said.

“The moment you put the new coffee shop near the transit station, it adds value,” Coes said. “Then we add the hotel near the coffee shop and the transit station. Then it becomes a place. The idea is to create a place where people want to go to.”

Coes urged local communities to begin working now, adopting zoning codes that would fit transit center and banking land to encourage development around them.

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