The Northern New England Passenger Rail Authority has been awarded an additional $3.4 million for track improvements and upgrades on tracks between Portland and Brunswick, according to U.S. Sens. Olympia Snowe and Susan Collins.

The authority will use the additional funding for new railroad ties, rehabilitation of three bridges, the construction of overnight holding tracks for trains in Brunswick, and the construction of a new passing siding along the line.

The money comes from the U.S. Department of Transportation.

Two weeks ago, Snowe and Collins announced that the authority’s competitive grant request for $20.8 million, for track improvements on the Downeaster line between Portland and Boston, was approved.

Snowe, a member of the Senate Commerce, Science and Transportation Committee, and Collins, ranking member of the Senate Transportation Appropriations subcommittee, wrote to Transportation Secretary Ray LaHood in support of this grant application.

“This additional investment in the Downeaster line will fund needed infrastructure improvements and help extend passenger rail service to Brunswick,” Snowe and Collins said in a statement today. “In addition, it will help improve mobility in Maine and around New England, increase rail ridership, boost tourism and create needed jobs in Maine.”

In January 2010, with Snowe and Collins’ support, the U.S. DOT awarded the authority $35 million in high-speed rail grants to rehabilitate 30 miles of track.

The Downeaster operates five daily roundtrips between Portland and Boston. Ridership has grown by 10 percent since last October.