Interstate 94 between downtown Minneapolis and St. Paul is a heavily traveled freeway with about 160,000 vehicles moving in both directions daily. The concrete pavement with asphalt repairs needed a major overhaul for at least a year. A 4.2-mile section in both directions on the St. Paul side was on the priority list for repaving and, with ARRA funding, the Minnesota Department of Transportation decided to complete the job before the annual Minnesota State Fair began in St. Paul in late August.
The challenge to the general contractor was the work must be done on four weekends from 8 p.m. on Fridays to 5 a.m. on Mondays during July and August. Paving contractor Hardrives Inc., Rogers, MN, received the Mn/DOT bid and began preparation work to relocate lights on the center median and sides of the freeway, rebuild catch basins, and build bus lanes on the outer edge of I-94, said Tony Kieger, Hardrives project manager. “We had about three months to prepare the freeway before the actual milling and asphalt paving,” he said.
“First, we hired People’s Electric, a subcontractor, to take out the lights on the length of the project. We added more concrete under catch basins at the sides of the freeway to support the weight of buses in the bus lanes. We hired PCi Roads, another subcontractor, to patch pier struts on all the bridges to keep them from deteriorating. Pier struts are under the bridges where the concrete has broken at the piers and exposes the rebar,” said Kieger. PCi Roads repaired the struts on bridges at Vandalia Street, Snelling Avenue, Lexington Avenue, Hamline Avenue, and Western Avenue.
Prep work first
After three months of preparation work, Hardrives was ready to begin milling the pavement, but Mn/DOT wanted the contractor to mill and pave in quarter sections of the freeway. “Mn/DOT wanted half of the eastbound lanes paved first and, then, finish the other half before we work on the westbound lanes,” Kieger stated. “We determined we couldn’t build the road that way because we had to mill the asphalt surface, put on the first lift of asphalt, install loop detectors that monitor traffic counts, and put on the second lift of asphalt.”
Kieger said Mn/DOT wanted 81 loop detectors installed in the lanes and ramps. Hardrives could install one detector an hour and hired Collins Electric to do the work.
“We could not finish all the installation from a Friday night to a Monday morning,” Kieger said.
Loop detectors are placed in every lane to provide traffic information to Mn/DOT. “You’ll see them at intersections, ramps and in every lane,” Kieger said. “They all have to connect together and are placed from the center median across all lanes to the sides where they transmit the information. We required the first weekend to install enough of the detectors to start paving on the second weekend while detectors were installed on the other half of the eastbound lane. We were trying to accomplish all the work with 100 trucks driving up and down the entire length of the project.”
Hardrives decided to mill and pave both sides of I-94 in two weekends. During the first weekend, Hardrives milled four inches of asphalt, laid two inches of new asphalt, and installed as many loop detectors as possible. When Mn/DOT closed the entire eastbound lanes at 10 p.m. on Friday, Hardrives brought in its new Wirtgen W2200 full lane milling machine, which covers more area than the half-lane machines.
“Our competitors’ machines were working too,” he said. “We had the Terex milling machine and a Roadtec machine and we saw how they would cut against each other. It took three 12-foot machines and a six-foot machine to mill the mainline and every entrance and exit ramp going east. The six-foot milling machine cut the narrow lane next to the median barrier.”
Tons of asphalt
About 200 employees of Hardrives and its subcontractors worked during that weekend to mill 38,000 tons of asphalt, patch certain areas, and convey the asphalt into trucks to be hauled to Hardrives’ three asphalt plants. “At times we had four sweepers to clean up and patch the cracks with two crews patching in front of the paver,” Kieger explained. “We also ran 60 trucks back and forth between I-94 and three asphalt plants with about 1,400 tons of materials an hour.”
On Saturday morning, Hardrives added another 38 trucks to haul materials. By midnight, milling on the eastbound lanes, more than 20 lane miles, was completed. The project included 4,000 tons of asphalt used to pave all the ramps and some connecting roads.
The warm July weather brought an unforeseen problem. “When we put the first lift of asphalt on the pavement, the concrete underneath it buckled and, literally, lifted up the new asphalt,” Kieger said. “We had to dig it out and patch three spots in each direction. In one spot, we filled 200 tons of asphalt patch. This showed that the concrete pavement was well worn.”
During the second weekend, another two inches of asphalt was placed on both sides of I-94 for a total of 83,000 tons of material using about 20 percent recycled asphalt from the milling process. Three paving crews worked on this weekend to complete all the ramps on both sides of the freeway. “Every weekend that we were working, we finished on Sunday evening usually by 6 p.m. although we had until Monday morning to complete the job,” said Kieger.
On the last weekend, Hardrives painted stripes on all lanes, conducted a profile to obtain a road smoothness rating, and opened both sides of I-94.
In addition to the new Wirtgen milling machine, Hardrives also bought three new Hamm HD 140-VO 84-inch double drum oscillatory rollers. Ken Boehm, sales representative, Hayden-Murphy Equipment Co. in Bloomington, sold the four pieces of equipment to Hardrives. “On the compactors, the front drum is vibratory—up and down motion—and the rear drum is oscillatory—back and forth motion. Hamm is the only manufacturer with an oscillation system in the rollers,” said Boehm. “You can achieve the desired compaction at cooler temperatures without crushing the aggregate as you can with vibratory rollers. The rollers are more efficient on certain type of mixes and burn only 2.45 gallons of fuel per hour.”
More efficient equipment
The Wirtgen milling machine is a state-of-the-art full lane machine, 12.5 feet wide, with 950 horsepower. “It grinds asphalt or concrete and delivers the material on a conveyor into dump trucks,” Boehm explained. “This is a fuel-efficient machine because of its design compared to machines with similar horsepower.”
Kieger said, “With the Hamm compactors, we achieved density in the asphalt faster and easier because the drums have a little different rolling pattern. That’s a reason we can complete the project on four weekends.” The Wirtgen W2200 had two additional gadgets to speed up this project. “The new lighting system helped us work better at night and the watering system cleans the asphalt so there’s less material to sweep,” said Kieger.
Hardrives bought the equipment for large projects, such as the I-94 milling and paving. “We’re happy with their performance,” said Kieger, who emphasized that the German-made equipment have been updated in features and built better.
“Fortunately, we have enough equipment,” said Don Hall, vice president and co-owner of Hardrives. “If we worked a regular week, it would have taken a long time because Mn/DOT allows road work only from 10 p.m. to 5 a.m.” He stated that the Wirtgen W2200 is not the cheapest machine but gave Hardrives a competitive edge with its efficiency.
Hardrives, which began business in 1963, has worked on most Twin Cities highways, including I-694, I-494, I-394, Highway 169, and Highway 55. “This is the third time I’ve repaved I-94 and all of it was asphalt paving. We have been general contractor and subcontractor on the projects,” Hall stated.
The company owns asphalt plants in St. Cloud, Becker, Chisago, near Duluth and, this year, bought the former Tower Asphalt in Lakeland, all in Minnesota. About 300 employees work for Hardrives to produce 1.4 million tons of asphalt annually. n