Hoffman Construction Co., Black River Falls, Wis., is performing the site-preparation work on five-and-a-half miles of the new Highway 57 in Door County for the Wisconsin Department of Transportation (WisDOT).
Started in January of this year, site work on the section has been moving ahead steadily as Hoffman moves 15,000 cubic yards to 20,000 cubic yards of rock and dirt daily to prepare the path that will support the roadbed and will form the slopes and ditches alongside it.
Hoffman's site preparation for this segment of the new highway will be completed by November, with nearly all of the large-scale earthmoving finished in August if the weather continues to cooperate.
Paving of the segment, which will be bid separately, is scheduled to take place in 2008.
Hoffman's $6.0-million contract is part of a $72.5-million overall expansion that will upgrade and convert about 25 miles of the existing Highway 57 from two-lane undivided highway to four-lane highway with a median and fewer intersections.
Highway 57 is the major highway that carries a daily total of 10,000 to 13,000 industrial, commercial and personal vehicles between the cities of Sturgeon Bay and Green Bay. It is also the main route for the two million tourists who visit the Door Peninsula each year.
The upgrade will provide additional roadway capacity to serve existing and future traffic volume, improve the highway's safety and efficiency, and help develop the region's economy.
Along most of its length, the new, four-lane highway is being constructed along side the existing two-lane highway, which will be resurfaced and turned over to the local municipalities and counties when the new road has been completed.
Construction on the overall Highway 57 expansion project started in summer 2004 and is scheduled for completion in 2008. It is being done in several legs, with different contractors working on various sections.
The five-and-a-half-mile section from the Door County line to Pleasant Ridge Road that Hoffman is working has presented a wide range of challenges.
Barry Paye, P.E., WisDOT's project leader on this job, said, "This segment has presented us with just about every type of soil you can encounter, from topsoil to sand, silt, clay, mixed soil, marsh, and rock. Of the 1 million cubic yards of material we will move here, about 250,000 yards is rock, some limestone and dolomite so hard it has to be blasted. When we remove rock, we spread and compact it to form a solid hauling road that will later become a firm base for the highway's roadbed."
In addition to using the rock to good advantage, the operation is using soil removed from high places on the site to fill low areas. One of the early phases of work on this leg was placing 230,000 cubic yards of soil left from work on the previous leg of the highway as fill for the current section. It took about 10,000 truckloads to complete that part of the job.
Consideration for the local ecology has also affected the work process. Steve Noel, WisDOT's district project development supervisor, said, "Five streams cut across the path of the new highway in this area, so we needed to build five box culverts and two slab span bridges over those streams. Because fish spawn in the streams between March and May, we had to complete all five stream-related structures before March first — or wait until June to construct them. Waiting would have hamstrung Hoffman's ability to work the site and meet the schedule, so the subcontractor building those structures made sure to complete them before spawning season."
Erosion control is also vital, to prevent dirt from washing off the site and into waters of the nearby bay of Green Bay. Hoffman is using fabric barriers to prevent erosion and is immediately planting grass on all finished side slopes to help hold the soil in place.
Even with the challenges, site preparation is going smoothly.
Hoffman has two grading crews and a fleet of up to 37 pieces of equipment working the project. The fleet of equipment has included up to 12 scrapers, eight off-road dump trucks, 15 pusher-dozers, one grader, and one hydraulic backhoe. There are currently six scrapers working the job. All of the equipment is Caterpillar.
Moving 15,000 cubic yards to 20,000 cubic yards of dirt per day requires 600 to 700 scraper loads. The work site is a steady stream of scrapers and dozers working in concert. Each scraper can hold 26 cubic yards of dirt and is pushed along by one or two of the dozers as it shaves away a layer of earth. Each filling takes between 15 and 30 seconds. When the scraper is full, it pulls away from the dozers and travels off to dump its load before heading back for the next pass.
After the scrapers have removed the bulk of the soil, a grader does the fine finishing work on the area that will support the paved roadbed and shoulders, while the dozers grade the adjacent slopes and ditches.
WisDOT is using this project as a pilot to test the effectiveness of GPS guidance systems for highway site preparation. Hoffman has one GPS-equipped dozer and one GPS-equipped grader on-site. Both are equipped with the Trimble GPS system. WisDOT has created 3-D electronic models of the highway design, which can be loaded into Hoffman's GPS system to guide equipment operators in grading to precise elevations and grades.
The results of the tests have been excellent, according to Paye and Noel, who say that the grade for the roadbed, the slopes and the ditches have all been within 1/10-foot — even more precise than required in the design's specifications.
Said Noel, "Our test procedure addressed grading accuracy only in the area under the road and shoulders. But the GPS-guided test grading has maintained the accuracy over the even larger area that includes the slopes and ditches, too. GPS-guided grading appears to work very, very well."