LEWISTON – A new transportation study aims to find the best way to connect Portland, Auburn and Brunswick in terms of cost-effectiveness, land use and overall community benefit.

The Portland North Alternative Modes Transportation Study will compare bus service from Portland up interstates 95 and 295 to a commuter rail network among Portland, Yarmouth, Brunswick and Auburn.

At stake is up to $75 million through a new category of federal grant, the Federal Transit Agency’s Small Starts program.

“One criterion is to remove 1,000 cars a day from the roads,” said MDOT’s Tracy Perez. “So, one of the big things we’ll be looking at is cumulative ridership.”

Perez said there are two basic options. One would create a regional bus service connecting Portland to Auburn and Brunswick. At least half of the regional bus route would have to be on dedicated rapid transit lines. That could mean building a road just for buses, or adding high occupancy vehicle lanes to I-95 and I-295.

“That works very well for many of the cities we’ll be competing against,” Perez said. “The Chicagos and Los Angeleses already have those kinds of lanes. It’s something we could look at, but it’s very expensive.”

A regional commuter rail service would use existing rail lines between Portland and Yarmouth and among Yarmouth, Brunswick and Auburn.

Plans to build a passenger intermodal facility in Auburn will help, she said. That facility would be south of the Auburn-Lewiston Municipal Airport.

“The fact that it’s central to the highway, close to the rail lines and the airport make it fit perfectly with either alternative,” she said. “It’s a key part of the plan. It’s one of the reasons we are doing this process.”

The study is due to be completed by the fall of 2009. Right now, the MDOT is looking for fatal flaws in either alternative.

“We’re looking to see if any part is so expensive or unpopular that we shouldn’t go forward,” she said. “That’s so we won’t waste money on doing something that doesn’t make sense.”

The fatal flaw analysis should be finished by October, she said.