In relocating Highway 53 in Virginia, Minnesota, Kiewit Infrastructure Co. is building one of the tallest bridges in the state for the Minnesota Department of Transportation (MnDOT), a $156.4 million project that's tracking close to budget and ahead of schedule, thanks to collaboration among the team members.

"We have to have everything out of the way by November of 2017," said Pat Huston, Project Manager for MnDOT.

When U.S. Steel granted MnDOT temporary rights to build Highway 53 more than 50 years ago, the easement required the highway to move if the mining company wanted the ore beneath it. According to the easement, U.S. Steel would be responsible for the move until 1987, and MnDOT would be responsible for the move after 1987. The easement also stated the highway must be moved within three years of notice. 

In 2010, Cliffs Natural Resources and RGGS, U.S. Steel's successor, notified MnDOT the easement rights across the United Taconite Mine would end. The state and RGGS negotiated a turnover date in November 2017.

MnDOT considered several alternatives, including purchasing the land, but that proved too expensive, with the value estimated at between $400 million and $600 million. Additionally the taconite mine brings economic vitality to the area. Taconite is turned into pellets to create steel products. MnDOT considered two other routes, but they came with unacceptable risks.

Officials decided on building a new highway in a loop east of the original road. The department has purchased the mineral rights under the new alignment, so it will not have to move the road again. The new route includes construction of a diamond interchange at Highway 135 and a 204-foot-tall bridge over the Rouchleau Pit, which provides the city of Virginia's water supply. The project also features relocating the Mesabi Trail and the city's water and sewer lines.  

Taking a Collaborative Approach

MnDOT began an accelerated construction process, with many activities occurring concurrently. The department decided to use the construction manager/general contractor (CMCG) delivery method. The legislature has authorized 10 projects in the state that can try the construction-manager approach. The Highway 53 project is the second CMGC project for MnDOT.

"I'm a real advocate for CMGC delivery," says Rob Ramer, Project Manager with Kiewit, based in Omaha, Nebraska. "This has been a real success. The strength is you build an active teamwork. There's a win-win and alignment of goals going through the preconstruction period. You get the ability to understand the issues driving the decisions in the contract plans. With that knowledge you are in a better position to proceed."

Kiewit, as the construction manager; the department; and engineers from Parsons Transportation Group in Minneapolis co-located in the Twin Cities during planning phase. That led to finding alternative solutions to potential problems and savings of money.

"Everyone had their sleeves rolled up working on the project, all wearing the same jerseys," Huston says. "Failure was not an option. Together, we figured out how to make it happen, and we haven't missed a milestone."

The team started working together in March 2015, and designed at risk before the environmental impact study was complete. The grading and bridge plans were complete in October 2015, and crews started construction on November 2, 2015. 

"It was not business as usual to make this happen in nine months," Huston recalls. "We turned our system upside down out of necessity."

A state sub-cabinet was created to help clear the path and supply resources from other departments. That pulled resources from many other initiatives to build Highway 53. Both Governor Mark Dayton and MnDOT Commissioner Charles A. Zelle supported and were engaged in making this project happen.

Kiewit has worked 120-hour weeks, double 10-hour shifts, six days per week. Ramer expects to continue working through the winter. The night work is taking place under mobile lights on the road portion of the contract but not the bridge.

"Most all of the night shift work has been grading, excavations and borrow," Ramer says. "It's risky to provide crane services at night. Once we committed to finishing the project early, roadway construction operations became critical to the project completion, and there was only limited potential benefits to working bridge operations at night during 2016."

The department also purchased the $17 million in steel for the girders at risk, since it takes so long to fabricate.

Constructing the New Alignment

Work began in November 2015 and is now more than two-thirds complete. Starting from the east, the project entails construction a new interchange at Highway 135, then building the new 3-mile road alignment, a 95-foot-wide bridge over the abandoned mine pit and a new intersection at 2nd Avenue on the west.

About 800 linear feet of the roadway alignment passes through a solid rock cut on the east approach. Crews excavated down through 15 feet of overburden, and then 20 feet of rock to construct the roadway. An additional 15 feet of controlled blasting at the top of the two high walls was required for the abutment foundations. The native soils are silt and clay.

Kiewit has excavated more than 1.25 million cubic yards of fill and embanked about 600,000 cubic yards. To build the road, crews will place 30 inches frost-free granular material and 6 inches of aggregate base before paving with asphalt. The granular subgrade and aggregate base materials were processed from taconite mining waste products.

Traffic must be on the new alignment and the existing highway infrastructure must be removed by November 2017 and everything out of the way for mining operations to commence. Kiewit can earn incentive bonuses for opening the bridge earlier. Ramer hopes to deliver it 60 days early to earn the full bonus. Some additional work - a sealant on the bridge, clean up and landscaping - will take place early in 2018.

Building the Bridge

The road crosses the Rouchleau mine pit, with its nearly vertical walls. An access road on the western side allowed crews and equipment to get down to the site on that side. But to build the other pier, crews would have been worked from barges in the water. Kiewit suggested filling the area beneath the bridge, between the piers with rock.

Although it sounds like a straight forward idea, MnDOT was unsure environmental permits would be granted to place fill in the water.  Part way through the project development process, environmental regulators determined that fill in the water would be allowed.

"We decided to embank a rock-fill causeway in the mine pit that would bring the surface above the water to use crawler cranes and store materials on," Ramer says.  

Kiewit used 40-ton, off-highway haul trucks on the access road to bring in 310,000 cubic yards of clean rock to create the 170-foot wide causeway. Crews dumped the rock and moved from west to east until it was filled in. That rock, 8 to 24 inches in diameter, was compacted and covered with a waterproof rubber membrane, placed 30-inches of aggregate, and then rolled and compacted to form a structural section. Double turbidity curtains and an impermeable liner on the causeway were used to protect the public water supply from any contaminants.

That causeway will stay for access for future maintenance.

Huston called the change from barge to fill one of the big successes of using the construction manager approach. Kiewit's idea saved the project $5.5 million and considerable time. It also created a safer job site.

"We would much prefer to have a solid foundation under our cranes during erection of steel," Ramer says. "It makes for a much safer operation."

The steel bridge girders range in height from 9 feet, 6 inches to 14 feet, 6 inches tall. Eighty pieces of steel cross above the service road, eight girder lines with 10 pieces. The tallest beams are used at the two major piers.

Kiewit is using a Terex Demag 6800 Crane, with a 350-long crane boom. The causeway has to remain flat for the crane. The team regularly monitors the causeway for settlement and used sonar to verify the accuracy of the construction of the rock slopes. 

The causeway buttresses the foundation of the piers. One pier is founded on solid bedrock and the other on 170 feet of blasted rock mine-waste product. Temporary supports keep the girders positioned until the beams are all in place.  

"We drilled down through that with 30-inch diameter steel cans through to bedrock," Ramer explains. "By leaving the causeway embankment it provides additional stability to the pier, which [extends through fill into solid rock]."

Kiewit will pour the concrete deck as soon as weather allows. Crews also will remove the existing highway, bridges and utilities within the mine right of way.  

"We have a lot of work to do in 2017," Ramer says. "We need good spring weather to get the grading done. We will push for that early finish."