Three designs are being floated by transit planners for a bridge to carry light-rail trains through the Kenilworth corridor of Minneapolis — a hotly contested component of the $1.68 billion Southwest line.

The bridge, part of the proposed 16-mile transit line, will span the channel between Cedar Lake and Lake of the Isles in Minneapolis. The existing wooden railroad bridge would be replaced with “new low-profile structures,” according to the Southwest Project Office, an arm of the Metropolitan Council.

The renderings will be discussed Dec. 3 by members of a Southwest Corridor management board.

Public input will be sought through 2015.

The transit line would connect downtown Minneapolis to Eden Prairie, passing through St. Louis Park, Hopkins and Minnetonka. It is expected to be completed in 2019.

The pathway of the light-rail line through the residential corridor has drawn fierce opposition among some residents, and a federal lawsuit seeking to block the project is pending.

The projected cost of the bridge, already budgeted, ranges from $4 million to $7 million. The price tag will depend on the design.

The steel pier concept for the light-rail bridge.

Three different bridge concepts feature an arched pier, a thin deck and a steel pier, all of which are supported from below with three rows of piers. The current bridge is supported by six piers.

“These are not full-blown designs,” Jim Alexander, director of design and engineering for the project, said in a statement Monday. “They are just in the idea stage for discussion as part of our consultation process for historic properties.”

The plan calls for hiding the light rail in a tunnel south of a channel between Lake of the Isles and Cedar Lake. The light-rail trains would surface to cross the bridge over the channel and run at ground level north through the corridor.

The thin deck concept features light-steel railings, which “lessens the visual impact of the bridge over the channel.” Charcoal-tinted concrete would “reinterpret” the existing wooden railroad bridge, according to the Met Council. The steel pier concept features natural steel railings that will “weather in a couple of years to a warm brown patina.” And the arched pier concept has a concrete deck with steel railings, “recalling the essence of the existing rail bridges of the Chain of Lakes area.”

All of the designs call for a clearance of 14 feet from the water surface to the bridge beams to allow navigation for recreational users.

Mary Pattock, a spokeswoman for the Lakes and Parks Alliance of Minneapolis, the group suing to block the project, said the three renderings would be “attractive if they spanned the Mississippi River. They look like a humongous freeway that violates a delicate and peaceful woodland channel.”

Pattock said the push to approve the renderings is premature — that the alliance feels that more environmental studies are needed along the corridor before the project moves forward.