PORTLAND – Railroad police with jurisdiction over rail corridors are being especially vigilant dealing with trespassers and motorists who run crossing gates as Amtrak begins service from Boston to Portland.

Authorities are concerned that motorists and pedestrians accustomed to lumbering freight trains will get a surprise from the fast-moving Amtrak trains.

At 60 mph, the Downeaster runs twice the speed of most freight trains, and police are worried about collisions with pedestrians and motor vehicles. Amtrak hopes eventually to boost the speed to 79 mph.

Old Orchard Beach police Chief Dana Kelly said many people have found it easy to avoid the slow-moving freight trains, but that the fast Amtrak trains may surprise them.

“They may not be as lucky,” Kelly said.

Earlier this week, Kelly and representatives of other local police departments flew in a helicopter provided by Amtrak for a better view of the railway.

Police from Old Orchard Beach also have been working closely with the railroad police, which patrols 1,500 miles of track in New England and New York. The railroad police are hired by the railroads, but have the same authority as state troopers.

In Maine, there are three railroad police officers assigned to nearly 400 miles of tracks owned by Guilford Rail Systems. They travel in unmarked cruisers.

The deaths this weekend of three teen-agers in suburban Philadelphia, struck by an Acela Express train traveling at 100 mph, highlighted the importance of fences and security patrols along train routes in heavily populated areas, officers said.

The railroad police lately have been spending a lot of time in Old Orchard Beach. The tracks there run directly through the center of downtown, about a quarter-mile from the beach that attracts tens of thousands of tourists.

In addition to Old Orchard, police also are worried about large encampments of homeless people they have found in the wooded areas along the tracks in Portland and near the station at Sewall Street.