Shallow tunnels recommended for Twin Cities' Green Line light-rail extension

Building shallow tunnels for light rail along the preferred route in Minneapolis is the "most cost-effective solution and best long-term investment" for the Twin Cities region, Green Line Extension planners recommended to the Southwest Corridor Management Committee and Metropolitan Council, which oversee the project.

As a result of the recommendation, the project's new cost estimate is $1.56 billion, up from the earlier $1.25 billion that did not include the cost to address the location of freight rail in the corridor, Southwest Corridor and Metropolitan Council officials said in a press release. The Federal Transit Administration in 2011 directed the council to study options to keep freight rail in the light-rail route through the Kenilworth neighborhood of Minneapolis in addition to studying how to reroute Twin Cities & Western Railroad Co. trains to St. Louis Park, which drove up the cost.

"This really became two projects in one: build a light-rail line and include the cost of any freight-rail adjustments," said Mark Fuhrmann, who leads the light-rail project development for the council. "The shallow tunnel option is the best option because it ensures conditions in the Kenilworth neighborhood will be the most similar to existing conditions today."

Planners also recommended building a maintenance facility in Hopkins, Minn., and making other adjustments to the line's proposed alignment in Eden Prairie, Minn.

The corridor management committee and Metropolitan Council are expected to review the latest recommendations today.