DOVER, N.H. -- Amtrak says maintenance, not safety, is the factor in a debate over the Downeaster’s speed, according to Foster’s Daily Democrat.

"An agreement was signed in January 1999 that said we could operate at 79 mph if the Surface Transportation Board issued an order, and that is what they did," said Bill Epstein, Amtrak director of government affairs.

The Surface Transportation Board ruled that the Boston-to-Portland, Maine, train could reach speeds up to 79 mph if the track met certain criteria for flexing under its weight.

Guilford Rail, which owns the tracks from Plaistow to Portland, says it has analyzed the test results and the upgraded track failed to meet criteria in nearly 1,000 location points.

"There were two sets of tests. The numbers are out there. That’s about all there is to discuss," said Guilford Rail Vice President David Fink. "The first sets of numbers were bad and the second set were worse," he said. "The bottom line is there are a lot of areas with a lot of problems."

Amtrak began the Downeaster service Dec. 15 at 59 mph. A speed of 79 mph would cut the time of a Boston-to-Portland trip by 15 minutes to two hours, 25 minutes. Currently, the trip takes two hours and 40 minutes.

Epstein said that 99 percent of the track meets or exceeds the threshold set by the Surface Transportation Board, according to preliminary data.

"The standards relate to design and maintenance, not safety," Epstein said. "It’s a matter of whether the track will last 70 years or 80 years."

To conduct the test, engineers use a special car with sensors towed over the track at 10 mph. The equipment on board measures how much the track moves up and down under the weight of the train. It took 100 measurements per second, or about 2.3 million measurements over the entire line. The special train conducted testing in September and again this month.

Fink said an additional 18 inches of crushed stone is needed beneath the tracks, in addition to heavier, 132-pound rail. Guilford cannot prevent Amtrak from using its rails, but can set speed limits. If Guilford and Amtrak cannot agree on a speed, federal officials will review the test data and set a limit.

The Northern New England Passenger Rail Authority, which oversees Amtrak’s Downeaster operation, coordinated a $52 million overhaul of the track along Guilford’s 78-mile length. Thousands of railroad ties were replaced, 190,000 tons of ballast was used to strengthen the rail bed and new, welded 115-pound sections of rail were installed. The rail authority made the improvements with a 79 mph speed in mind.

Amtrak operates at speeds of 80 mph and above on 115-pound rail -- and even 112-pound rail -- throughout the country, Epstein said.

"The Federal Railroad Administration was unable to identify any reason why the rail would not perform satisfactorily at 79 mph," Epstein said. "We wouldn’t operate at any speed unless we were convinced that it was safe to do so. The Surface Transportation Board and Federal Railroad Administration agree with us."