MILLINOCKET, Maine — State leaders predict vast improvements in northern Maine freight rail service with the start early next month of $10.5 million in federally funded repairs on 233 miles of decrepit state-owned railroad tracks between Millinocket and Madawaska deemed vital to the state’s economy, state officials said Friday.

The repairs “will really crank up in the next few weeks and continue until we get frozen out” by winter, said Nate Moulton, director of the Maine Department of Transportation’s rail program. Repairs will resume in the spring and finish at the latest by mid-October.

The repair preparation work, which began about three weeks ago, included tests of rails for subsurface flaws. The repairs will include the replacement of 50,000 ties and the adding of stone and resurfacing of railroad beds wherever needed, Moulton said.

The line’s previous owner and rail carrier, Montreal, Maine & Atlantic Railway, sought federal approval in February 2010 to abandon the tracks, citing losses of $4 million to $5 million annually.

Taxpayers saved the rail line in June 2010 by approving $7 million in borrowing to buy the tracks. They were purchased by the state last Jan. 14 for $19.1 million.

MM&A officials did not want to abandon the lines but said they had no choice. While still functional, the tracks have fallen into disrepair, with long stretches where safety concerns prohibit train speeds of more than 10 mph. The disrepair, plus a lack of product to haul, caused MM&A to miss deadlines or not run enough trains to make money or satisfy customers, rail officials said.

With a new freight carrier, Eastern Maine Railroad, handling traffic on most of the rail line and its branches since June 15 and repair prep work already under way, Moulton said he has hopes that the repairs will be finished in a year.

Moulton visited Aroostook County earlier in the week.

When the work is done, track speeds should increase from 10 to 25 mph to 25 to 40 mph. That will speed delivery times, reduce train company overtime expenses, improve freight service reliability and allow freight services to run fewer trains in less time, said Rob Elder, director of MDOT’s freight office.

“It helps everything,” Moulton said, adding that many of the 22 large-scale manufacturers on the northern Maine line have been enthusiastic so far about the service provided by Eastern Maine Railroad, which state leaders picked in April to be the primary delivery service on the 233 miles of track. MM&A also provides rail service on those and other tracks.

The repair contract expires in mid-October 2012, Elder said.

Everett Deschenes, manager of fiber procurement for the wood-pulp manufacturer Old Town Fuel & Fiber, predicted that northern Maine rail customers would see improvements once the tracks are repaired.

“We will probably see fewer delays in deliveries, though we haven’t seen that much,” Deschenes said Friday. “It will probably make the whole delivery system that much more efficient and with that, we are actually looking at increasing the volume we bring from up north.”

“There were many companies that had issues with MM&A, but we never did. We had a very good service from them,” Deschenes added.