PORTLAND – With train service between Portland and Boston still four months away, Maine transportation officials are already planning ways to extend service to Brunswick and Auburn within two years.

The first phase of Amtrak’s venture into Maine is slated to begin May 1. But the state Department of Transportation is beginning plans to extend service to Freeport, Brunswick and Auburn by the end of 2002 and 2003.

They’re also planning ways to link service in Maine to destinations beyond Boston, including Canada, Washington, Florida and Chicago.

With Maine sandwiched between two of the most successful railroad corridors in North America – Boston-to-Washington and Quebec-to-Toronto – the potential for a highly successful passenger and commuter system is huge, said state Transportation Commissioner John Melrose.

“We can tap into those two national systems,” Melrose said.

Extending rail service to Freeport will bring 300,000 one-way trips during the first year, according to the state’s market studies. That would be a huge financial boost for the relatively low cost of extending service such a short distance from Portland. Brunswick, where the train will turn around, is only 25 miles away.

Plans call for two scheduled runs a day between Portland and Brunswick, and four daily runs between Boston and Portland. Railroad officials have yet to say how much the rides will cost.

Brunswick is vital to the state’s long-range plan to give tourists a “car-free vacation.” Tourists could travel from Brunswick on a slower excursion train all the way to Rockport. From there, they could ride a ferry to Bar Harbor.

Melrose is also pushing a plan for train service from Portland to Worcester, Mass., which would enable passengers to continue as far as Florida and Chicago by train.

The line to Boston, in contrast, ends at North Station, so passengers will have to ride a shuttle bus to Boston’s South Station to continue south.

Meanwhile, the state is upgrading an aging railroad line between Brunswick and Rockland as part of a $33 million plan to restore passenger train service to the midcoast.

Passenger service could also be extended from Portland to Montreal, Melrose said, allowing Canadians to travel to Old Orchard Beach, as they did for decades before passenger service was dismantled in the 1960s.

That route would generate 280,000 trips a year, and those figures don’t include the number of Mainers who might travel to Quebec, he said.

Transportation officials will still have to tackle the issue of cost: Beyond the expense of upgrading the rail line, it costs money to operate a train for every mile traveled.

That’s why extending the line to Freeport and Brunswick makes sense, Melrose said – with 4 million visitors coming to Freeport every year, it’s a short trip with a potentially huge payoff.