Architects of the biggest transit project ever in the Twin Cities on Tuesday endorsed spending more than a hundred million dollars to hide the Southwest Corridor light-rail line in tunnels through a recreation area in Minneapolis.

The pivotal recommendation is intended to quiet critics and buy political support for the transit project, but it won’t satisfy some Minneapolis residents who complain that the light-rail trains still would be above ground for too long in the wooded Kenilworth corridor of the city, an affluent area popular with bicyclists. If the city joins them in opposing the plan, the entire light-rail project to the southwest suburbs could be in jeopardy.

Some Minneapolis City Council members Tuesday called on the Metropolitan Council, the agency planning the project, to delay action so that alternatives could be explored.

“Let’s take the time,” said Council Member Betsy Hodges, a candidate for mayor. “Is this the best we can do?”

The plan by Met Council engineers is scheduled to go before a panel of metro leaders Wednesday for their review. If the metro leaders accept it, the plan could be sent to the full Met Council for a decision as early as next week.

The proposal calls for digging 1.4-mile-long tunnels next to existing freight rail and bike trails in the Kenilworth corridor at a cost of $160 million. It rejects rerouting the freight trains onto berms in St. Louis Park at a cost of $200 million, an option that drew strong criticism from that city and its residents.

The tunnels and other cost increases would bring the estimated price of the Southwest Corridor light rail to $1.56 billion, up from an earlier estimate of $1.25 billion.

Excavation would require the removal of about 1,000 trees and disrupt bike trails and motor vehicle traffic for about two years. But the trails would eventually be restored and trees replanted in the corridor, agency officials said.

“We will work to develop a strategy to revegetate the corridor that removes hundreds of buckthorn and volunteer trees,” said Mark Fuhrmann, Metro Transit’s engineer in charge of transit.

The tunnels would allow room for the existing freight rail and recreational trails to run alongside each other without the need to remove homes or businesses, as would happen to 30 properties in St. Louis Park if the freight lines were rerouted there.

The light-rail trains would emerge from the tunnels for about 1,000 feet to cross a bridge spanning a channel between Lake of the Isles and Cedar Lake. About 220 light-rail trains daily would each spend about 20 seconds above ground or above water near the channel.

Impact disputed

Fuhrmann said Tuesday that sinking the light-rail lines in tunnels alongside existing freight rail and trails would have less impact on the area than rerouting a few daily freight trains to St. Louis Park and putting hundreds of light-rail trains at ground level in the corridor. “A significant visual impact … is largely avoided,” he said.

But some nearby residents say the tunnels would allow the trains to be seen and heard for too long in the corridor, and they have collected money to finance a lawsuit to block the plan. The Minneapolis Park and Recreation Board, which controls property in the corridor, also has threatened legal action.

The city of Minneapolis voted years ago to accept the light-rail line on condition that the freight traffic was moved; some residents and officials continue to hold out hope for a reroute.

The Met Council is required under state law to seek the consent of the five cities along the future light-rail route, and it could face a tough time winning approval from Minneapolis. Underscoring that challenge, Met Council Chairwoman Susan Haigh recently held closed-door meetings with city officials whose support she needs for the tunnels.

“I made it clear I wasn’t buying what she was selling,” said Council Member Lisa Goodman, who represents the corridor where the light rail would go.

Rybak wants reassurance

Other city officials, while favoring a reroute, have left open the possibility of endorsing some version of the tunnels. Minneapolis Mayor R.T. Rybak sent Haigh a letter last month outlining his concerns about the tunnels but seeking assurances they could be built without damaging lakes or permanently eliminating trails or trees.

The recommendation on Tuesday for digging tunnels carries weight because the 17 members of the Met Council are appointed and rely heavily on their staff for direction.

To compensate for the costs of the tunnels and other new expenses, the engineers also recommended eliminating the last station proposed for the line at Mitchell Road in Eden Prairie to save $75 million.

They didn’t recommend another idea they recently considered — digging only one tunnel south of the channel and building the light rail at ground level north of it. That option would have preserved the 21st Street station in the Kenilworth corridor — which is eliminated under the plan for two tunnels — and reduced tunnel costs from $160 million to $100 million. But it would have drawn even greater opposition from Kenilworth-area residents and the city of Minneapolis.