Construction of a tunnel for the Southwest light-rail line in a narrow stretch of Minneapolis' Kenilworth corridor may have led to cracking in walls and floors at the nearby Calhoun Isles condominium towers.

Work on the light-rail line near the condo complex has been halted while the cause and extent of the cracks are investigated by the Metropolitan Council and its hired engineering expert, Socotec, a structural engineering firm.

The cracks were discovered by residents in hallways and common areas between the third and 10th floors of the condo towers, according to a memo sent by Southwest LRT Community Outreach Coordinator David Davies to the Calhoun Isles Condominium Association.

"Residents observed separation of the carpet tiles and separation between the walls and ceiling," Davies wrote.

In a statement this weekend, Met Council spokeswoman Terri Dresen said: "We are currently investigating the extent of the cracks. The cause of the cracks has not been determined."

Southwest project staffers investigated the cracks on Jan. 28 and Socotec was engaged to evaluate the damage. The council said it would cover the costs related to the investigation.

The news comes in the wake of the Met Council's recent announcement that the cost of building Southwest will rise by $450 million to $550 million, putting the total project cost at around $2.7 billion. The council also said it will take another four years to complete the line.

The most recent news "is a very, very troubling development," said Rep. Frank Hornstein, DFL-Minneapolis, on Friday.

Work on the tunnel in the Kenilworth corridor is a leading contributor to cost overruns and delays. The tunnel will squeeze through a crowded area of the corridor that also will accommodate freight rail and a bike and pedestrian trail above ground.

The Southwest line will connect downtown Minneapolis to Eden Prairie, with stops in St. Louis Park, Hopkins and Minnetonka. Some 220 light-rail trains will use the tunnel daily, assuming the line begins service in 2027.

A bipartisan chorus has been growing in recent weeks at the Capitol among legislators and Gov. Tim Walz for an independent audit to determine why the project's costs and timeline have ballooned.

Damage to the unusual condo towers has been feared by residents who have lived there for some time. Originally built between 1915 and 1928 as grain elevators, the structure was adapted for residential use in the 1980s.

The complex on Dean Court includes a high rise, some detached townhomes and a parking garage. The high rise comes within two feet of the Southwest tunnel, and the parking garage's footings are just inches away.

Many residents of the complex have long worried about how tunnel construction might affect the unique structure, particularly after the erection of new condos on nearby W. Lake Street in 2015 caused cracking in walls and ceilings.

The Met Council opted to use a different method to build the tunnel near the Calhoun Isles complex that was intended to mitigate pounding and vibrations during construction. It involves special equipment pressing — as opposed to pounding — vertical steel sheet piles into the ground, to create an interlocking wall that will serve as the framework for the concrete tunnel. But it has added time and expense to the project.

The project installed a monitoring system to track vibration and movement in the Calhoun Isles building, Dresen said, adding that council staffers have met weekly or biweekly with condo association representatives to address their concerns.

The Met Council has deemed the buildings "safe for residential occupation." So-called "crack monitors" have been installed to help assess damage and detect any further movement.

Vanne Owens Hayes, president of the condo association, said Sunday that the group would have no comment until it had a discussion with residents. A meeting between the roughly 200 residents who live there and Southwest project staffers is scheduled Feb. 15.

In recent years, the condo association has spent at least $250,000 on legal and technical consulting fees related to the project.

Hornstein and Sen. Scott Dibble lobbied successfully to get a mitigation process adopted by the Legislature to ensure condominium association residents had a voice during Southwest's construction and operation.

"The fact that these condo towers are showing cracks resulting from construction is no surprise," said Dibble, DFL-Minneapolis.

"Residents and elected representatives have been warning the Met Council for many years that they were running a huge risk that there would be damage to property," he said. "The Met Council refused, until forced by law, to do an analysis."