Cranes swinging day and night on new Vikings stadium

The high point of the prow is in place. The concrete scissor ramp has been poured. The loading dock leads under the building from the street. The steel skeleton snaps into place more each day on the $1 billion NFL stadium going up in downtown Minneapolis.

Down in the dirt pit of the stadium construction site on Monday afternoon, the heavy equipment beeped steadily from all directions, an audible signal of the constant movement of concrete and steel by some 650 workers on a finely calculated path toward opening day in 2016.

M.A. Mortenson Co. and the Minnesota Sports Facilities Authority took two dozen reporters on the first hard-hat tour of the project since demolition of the Metrodome in January gave way to the $1 billion structure's rise from the ground.

From the street, it's a marvel of synchronicity. Up close, it's all bigger and dustier.

On what will become the 50-yard line lie the solid oak tracks to support the massive crawler crane brought on site to lift the heaviest chunks of steel that will form the building's roof.

The biggest piece, a 740,000-pound ridge, currently lies in the dirt, awaiting its mid-November date with the crawler crane. The crane will hoist the ridge piece into place, where it will eventually form the backbone of the roof.

Cranes are the key. Construction manager Dave Mansell says it's about "maximizing hook time" right now. Most everything at the site needs to be lifted and set down.

A 4-D computer model shows the project progressing piece by piece, plotting some 20,000 movements. "I can go click on any date in the calendar and see what the building's going to look like at the day and time," Mansell said. The software has eliminated what he called those unfortunate timing mistakes where you swear and say, "What do we do now?"

As of last month, the project was 23 percent completed, with some $184 million in work finished, said Allen Troshinsky, vice president of operations for Mortenson. About 55,000 cubic yards of concrete have been put into place. Mechanical and electrical structures are going into place and some masonry has begun. "There's a lot going on behind the scenes that you can't really appreciate right now," Troshinsky said.

Because the project is so huge, multiple trades can work concurrently on parts of the building, meaning it's a busy construction site.

Reporters were led down the building's loading dock on foot. An adjacent dirt access road is used to get equipment into the pit to keep stress off the new concrete dock.

"Don't you just feel like you are in the stadium?" authority chairwoman Michele Kelm-Helgen asked on her way down the ramp. The dock can accommodate four television satellite trucks. Above ground, there will be room for 16 more.

Only heavy winds can slow the work down. Said Mortenson construction senior vice president John Wood, "We're obviously hoping for a little better winter than we had last year." Some parts of the structure already are getting wrapped in heavy-duty insulation so interior work can stay on pace for winter.

"We don't stop doing anything here," Mansell said before he turned to walk down the gravel hill. "I'm going to go back into the hole."