AUBURN — Establishing regular rail service between Auburn and Portland in 2020 could cost up to $234 million to start and could require an $8 million annual subsidy, according to a new study presented Wednesday night.

Transportation planners from AECOM told an Auburn crowd that extending that service to Montreal could cost up to $900 million in inflation-adjusted 2020 dollars but the service could attract an additional 204,400 passengers to the Amtrak Downeaster service.

“This project and the way that services have grown in Maine so far is much better than most (Amtrak) services in other parts of the country,” said Project Manager Jay Duncan. “So that’s encouraging. We may have a long way to go, but it’s still positive.”

Local transit officials and rail supporters had some quibbles with the study’s numbers. But state Rep. Mike Carey, D-Lewiston, said that at least Lewiston-Auburn had the study.

“This is definitely a start,” Carey said. “Before Brunswick was able to get their rail expansion, they had a study like this on the books for a couple of years. This is just what we need to be ready.”

The study, commissioned by the Maine Department of Transportation, looked at the feasibility of adding intercity train service first between Portland and Auburn then up to Bethel and finally through New Hampshire to Montreal.

The study also looked at the short-term costs of creating a dedicated intercity bus service between Bethel, Auburn and Portland that would be linked to Downeaster schedules.

Transportation Planner Adam Streit said the study called for eight Amtrak round trips daily between Portland and Auburn, with three of those being “single seat” trips continuing to Boston. Passengers continuing on wouldn’t have to change trains on those trips. The other five trips would be Portland-to-Auburn shuttles, and all of the trips would take 40 minutes.

Bethel service would build on the Auburn trips, with 3.5 round trips to Portland and stops at South Paris along the way. Those trips would take an hour and 40 minutes between Bethel and Portland.

Finally, the service would offer two round trips daily between Portland and Montreal, each lasting seven hours and 40 minutes. Passengers continuing on to Boston would likely have to change trains in Portland.

The service would need massive capital investment, including work on the rail lines between Portland and Yarmouth, and on up through to New Hampshire, new train engines and cars and layover stations in Auburn and Bethel.

But Streit said it was hard to narrow those costs down, saying capital improvements on the Portland to Auburn leg of the line would be expected to cost between $107 million and $234 million, depending on negotiations with rail line owners and construction costs. Costs extending service to Bethel — including the Auburn costs — would be between $139 million and $361 million. Capital costs extending the lines up to Montreal would be between $676 million and $900 million, depending on conditions.

Transportation Planning Manager said those estimates used costs based on forecasted 2020 values — today’s costs adjusted for 4.6 percent annual inflation. The same was true for the annual subsidies needed to pay for the service.

Roland Miller, Auburn’s economic development director, said the numbers should be provided in current dollars so they can be compared alongside other capital investments in rail, especially the Downeast expansion between Portland and Brunswick.

“Or, give us the Brunswick costs in 2020 dollars,” Miller said. “That way, we can make a comparison.”

Others said the study didn’t take into account how many trips would go between Lewiston-Auburn and Montreal.

Sue Moreau of the Maine DOT said the written study should be finished next month. A copy of the group’s PowerPoint presentation should be available Monday on the Androscoggin Valley Council of Governments website, at www.atrcmpo.org.

staylor@sunjournal.com