Port Authority of Allegheny County has received the federal green light for construction of a light-rail extension to the North Side.

The Federal Transit Administration informed the Port Authority yesterday that a 60-day comment period had expired without congressional objections to using federal funds for the project. That cleared the way for the "full-funding agreement," meaning the FTA will provide 80 percent of the funds for the project.

Twin tunnels under the Allegheny River will link Gateway Center to the stadium area of the North Side.

Port Authority's Judi McNeil said site surveys and traffic studies will begin soon, with construction to begin as early as November on the North Side.

The current price tag is $435 million. The state is responsible for 16 2/3 percent of the total, and the county is responsible for 3 1/3 percent.

More details in tomorrow's Pittsburgh Post-Gazette.