The Sound Transit board of directors awarded a contract for track and signal improvements on the Tacoma-to-Lakewood rail corridor, boosted by a $4.6 million federal stimulus infusion that will help bring commuter rail service to South Tacoma and Lakewood.

The $4.6 million grant is part of $131 million in federal stimulus funds for transit projects in the Puget Sound region. Sound Transit will receive a total of $23 million for five shovel-ready construction projects in communities throughout the Sound Transit District.

The M Street-to-Lakewood Track and Signal project will upgrade seven miles of existing track and street crossings on the rail corridor from South M Street in Tacoma to Bridgeport Way Southwest near Lakewood Station, which opened for express bus service last September. The federal grant and other project savings will be used to help close the funding gap for work between D Street and M Street in Tacoma that is also needed to expand Sounder service south by 2012.

“This kind of construction project will get our economy moving today and keep us moving tomorrow,” said Sound Transit Chair and Seattle Mayor Greg Nickels.

The upgrades made along the seven-mile stretch of rail include all new track and signal systems and improvements to 11 at-grade railroad crossings to meet current passenger rail safety standards along the corridor, which Sound Transit purchased from BNSF Railway. Layover tracks for train storage will also be added north of Lakewood Station.