PORTLAND – Operators of Amtrak’s Downeaster announced Wednesday that they will suspend service between Portland and Boston during the week of next month’s Democratic National Convention.

Security measures imposed on the rail line during the convention from July 26 to 29 were burdensome, said John Englert, executive director of the Northern New England Passenger Rail Authority.

But in the end, the rail authority determined that few travelers planned to go to Boston that week anyway, Englert said. “Many of the customers said, ‘We’re not going to bother,'” he said.

Workers will use the time to make rail improvements as the Downeaster prepares for a speed increase this summer.

On Aug. 1, the Downeaster’s speed will be boosted along much of the track owned by Guilford Rail System, shaving five to 10 minutes off the trip between Portland and Boston, Englert said. The top speed will be 79 mph along four miles of the Guilford-owned track.

The Downeaster will travel at 79 mph along a 30-mile stretch by fall 2005, reducing the travel time between Portland and Boston to 21/2 hours, he said. The route now takes 2 hours, 45 minutes.

A decade-long dispute over the Downeaster’s top speed on Guilford-owned track between Portland and Plaistow, N.H., came to an end after Gov. John Baldacci personally intervened a couple of weeks ago.

On Wednesday, Baldacci, Englert, Guilford Vice President David Fink and Maine Transportation Commissioner David Cole appeared together at a news conference to announce that an agreement had been reached.

In the end, the state agreed to provide $1.5 million this summer and another $4.5 million next spring for rail improvements. That will also allow a fifth daily run by the fall of 2005, officials said.

“Our concerns were safety-related. The governor has addressed those concerns, and we’re ready to go forward,” Fink said.

The spending on rail improvements comes on top of $50 million spent to overhaul the Guilford-owned tracks in 2000 and 2001. Guilford had insisted that heavier rails should have been used in the original overhaul.

Guilford and other officials declined to second-guess whether Amtrak and the state should have used heavier rail to avoid the protracted fight. “I’m not going to beat a dead horse,” Fink said.

Rail officials and advocates said the higher speed should lure more riders, especially at a time of rising gasoline prices.

The Downeaster had operated at a top speed of 60 mph after going into operation on Dec. 15, 2001, with four daily trips in each direction between Portland and Boston’s North Station.

“Just the perception – being able to say ‘up to 80 miles per hour’ – provides that comfort level that I’m moving faster than I can drive,” said Wayne Davis of Trainriders Northeast, a rail advocacy group.

The train makes stops in Old Orchard Beach, Saco and Wells in Maine; Dover, Durham and Exeter in New Hampshire; and Haverhill and Woburn in Massachusetts.

Also on Wednesday, Baldacci announced a pilot project in which excursion trains will be operated between Portland and Rockland.