The Minnesota Department of Transportation plans to build the state's tallest bridge to replace a stretch of Iron Range highway that's about to vanish into a pit mine.

The big bridge was the route recommended Tuesday by the engineers and planners who have been working for four years to figure out how to reroute a section of Highway 53 that sits on top of a valuable ore deposit on land the state was only leasing from the mining companies.

Rerouting the highway around the mining operation and across a water-filled pit mine just east of Virginia will cost an estimated $220 million -- almost as much as it cost the state to rebuild after the collapse of the I-35W bridge . This recommended route, which now faces a detailed environmental and community review, was the least expensive of the three options the state was studying.

“This is MnDOT’s best thinking, and we want to hear from the public,” MnDOT Commissioner Charlie Zelle said in a statement Tuesday. “From an engineering and cost point of view, this route stands out. We expect that the environmental process taking place now will support it. However, we want to make sure we haven’t missed anything, and encourage comment on the recommendation.”

Highway 53, which runs from Duluth to International Falls and the Canadian border, is a lifeline for the Iron Range communities of Virginia, Eveleth, Gilbert and Mountain Iron. Uncertainty about the highway's future had haunted the communities for years, and left businesses unwilling to move to town or expand their operations until they were sure the highway would still carry customers to their door.

"We're happy with this route," said Virginia City Councillor Charlie Baribeau, one of the community leaders who has been keeping a close eye on the relocation planning process. "This is one of the preferred routes."

If all goes well, Baribeau said, the community was told construction on a 1,100-foot bridge across the Rouchleau Pit could begin as early as fall 2015. The bridge -- which would be even taller than the John Blatnik “High Bridge" in Duluth -- poses unique engineering challenges. It would be built on some of the hardest rock on the planet, across a quarry that serves as Virginia's water supply.

Two other proposed routes would have been even more expensive. A longer bridge across the quarry would have cost an estimated $360 million and a proposal to route the highway across an active mine pit would have cost the state at least $460 million.

The state's dilemma traces back to the 1960s, when Minnesota accepted the local mining companies' offer to run the highway across their land, at no cost. The catch was that if the mining company decided it needed access to the minerals under the road any time after 1987, Minnesota would foot the cost of relocating the highway.

In 2010, the two companies that currently own the land under the highway, United Taconite and RGGS Land and Minerals, alerted MnDOT that they would need access to the minerals under the road. The state asked for a seven-year grace period to come up with a way to reroute the road.

Cliffs Natural Resources, which operates an active pit mine that stretches to within 300 feet of the existing highway, hopes to begin mining the taconite under the highway by 2017.

The state's review process will study the preferred route, as well as the alternatives -- including the option of doing nothing. But selecting a preferred route is a crucial step forward for the project. Now, said Highway 53 project director Patrick Huston, the state can select a design firm and a contractor to begin planning the bridge.

“We understand this has been a long and emotional process for the community, and we appreciate the public’s patience,” Zelle said. “Because of the project’s complexity, however, we needed the time to make sure we made the right decision now to achieve the most efficient and effective outcome.”