PORTLAND – An independent consultant’s report shows rail improvements meet or exceed requirements for Amtrak’s Downeaster to travel safely at 79 mph, operators of the service said Monday.

Amtrak and the Northern New England Passenger Rail Authority contend the report bolsters their argument that the passenger trains should be able to attain top speeds that exceed the current limit of 60 mph.

But the report isn’t the final say.

Guilford Rail Systems, the owner of 77 miles of track between Portland and Plaistow, N.H., will have an opportunity to review the report. Then both sides will sit down to see if they can come to terms on an agreement.

Speed is important. The higher speed would shave 15 minutes off the Portland-to-Boston trip and increase its prospects for success, supporters say.

“I’d like to think we’re reasonable people. In light of the findings in the report, I hope we can reach an agreement on train speed,” Michael Murray, executive director of the rail authority, said Monday.

So far, there has been little agreement.

Guilford has contended all along that the rail authority should have used heavier rail during the track rehabilitation. Amtrak and the rail authority have maintained that Amtrak trains across the country operate on the same 115-pound rail used in the $50 million overhaul.

David Fink, Guilford’s executive vice president, said Monday he needed time to review the report before commenting.

If both sides agree, then the trains will begin operating at the faster speed. If they cannot agree, then the matter could go before the U.S. Surface Transportation Board, something Murray wants to avoid.

The Surface Transportation Board already intervened when the two parties became deadlocked on issues related to speed.

Chairwoman Linda J. Morgan acknowledged Monday in a statement issued in Washington that the longstanding dispute has been “unique.” She said she hopes a final resolution can be reached soon.

The tests of the track between Portland and Plaistow were ordered by the Surface Transportation Board to settle once and for all the dispute over how well suited the track is for higher speeds.

A special train operated by Colorado-based Transportation Technology Center Inc. conducted the tests in late September after several days of heavy rain that mimicked conditions during the spring thaw.

Amtrak and the rail authority said the report demonstrates that the average track modulus, which is a measure of track support, is double the criteria set by the Surface Transportation Board.

Furthermore, the report shows the track exceeds the board’s criteria for modulus on more than 99.95 percent of the track on which Amtrak plans to operate its trains above 60 mph, they said.

The Downeaster went into operation on Dec. 15 with four daily trips in each direction between Portland and Boston.

Stops along the line include Saco and Wells in Maine; Dover, Durham and Exeter in New Hampshire; and Haverhill in Massachusetts. Seasonal stops in Old Orchard Beach, Maine, will begin in June.