Reducing the curve and widening of the bridges at Exit 10 over Interstate 90 near Spearfish, S.D., will improve the line of site for motorists to improve safety on this busy intersection that sees commuter traffic between Spearfish and Belle Fourche.
Located on the western end of the state, traffic continues to increase with commuter traffic and truck traffic that uses Exit 10 to get to Belle Fourche, which is a shortcut to Highway 212 that runs east and west across central South Dakota. The exit is also seeing heavier use as equipment is transported to the oil fields in northwest South Dakota and in western North Dakota, explains Joel Flesner of the South Dakota Department of Transportation.
The $8.2 million project began during the spring of 2011 and is being constructed on an aggressive schedule. Revamping one bridge and building another would normally require 20 weeks, but prime contractor Grangaard Construction Inc., of Watertown, S.D., chose an accelerated 12-week plan which is being completed in two phases.
“This was set up to be a two-year project, but in the interest of being done this year, we proposed a new schedule,” said Yancey Grangaard, owner of Grangaard Construction Inc. “We have extra staff running 7 days a week, 24 hours a day.”
The accelerated schedule adds to the challenge of the project as crews tackle the complicated interchange. Interstate 90 takes a pretty sharp curve under the bridge as it crosses Highway 85, Flesner said. “Nothing is square, even the girders are curved.”
The original bridge consisted of two separate one-lane bridges but by the time construction is complete this fall the two will become one but will now carry two lanes of traffic in each direction and will include an additional lane for future growth. The existing two lanes of roadway on either side of the bridge necked down to one lane each way over the bridge. “We’re bringing the lanes together and changing the elevation of the lanes so they match each other to improve sight distance. Now it is like a divided highway,” said Flesner.
The changes also will make it possible to remove the curve from the center of the bridge, Grangaard said.
“Now there is a 3-foot tall curve there. The change also improves the line of site for two service roads, one that leads to northbound property and one for County Road 14 turning traffic, giving them more of a chance to maneuver while providing a better view.”
Work on the Phase I consisted of a lighter work load in order to meet the July 29 deadline, which lands just before the start of the annual Sturgis Motorcycle Rally begins, but crews beat the deadline by one week, Grangaard said. The Rally brings close to a half a million motorcycles to the area, making it difficult to continue road work. Once the rally ends in mid-August, work will begin on Phase II, which includes the bulk of the work load.
In addition to constructing an entire bridge, Phase II requires the finishing work of seeding and installing lighting, causing this portion of the project to take longer. Crews also will update storm sewer and inlets in the median and install street lighting at the bridge and along the highway towards Spearfish. A Phase II completion date is set for Nov. 4.
Bridge work during Phase I is mostly repair work so 85 percent of the bridge remained in place, saving time and money, Grangaard said. The southbound bridge, which will be completed during Phase II, requires building a completely new two-lane structure that will be attached to the existing northbound bridge.
When finished, the 330-ft. (100.6 m) long bridge will be about 86-ft. (26.2 m) wide with two lanes in each direction, turn lanes for east and westbound traffic and a center median for future use. For now the bridge will have a wide curb in the center to prepare for the future, should extra lanes be needed, Grangaard said. About 1,100 cu. yds. (841 cu m) of concrete was needed for the bridge deck.
At the end of July, crews finished modifying the abutments of the Exit 10 northbound Bridge, reconstructing the northbound lanes of Highway 14L and Highway 85, and constructed a two-lane asphalt roadway for Brookview Road that will combine access for Brookview Road and Rio Drive to Highway 85. During the course of construction, access for Brookview Road was moved about 1,500 ft. (457.2 m) north where Rio Drive currently intersects Highway 85. The service road is being moved north to get it away from the intersection. Rio Drive will be altered to intersect the new Brookview Road alignment, according to information from the South Dakota Department of Transportation.
Also, Highway 14L and Highway 85 will be reconstructed from its current configuration of a divided asphalt roadway to a 5-lane undivided concrete roadway with a raised median. Reconstruction will extend from 1,300 ft. (396.2 m) south of the Exit 10 interchange bridge to 3,300 ft. (1,005.8 m) north. Storm sewer will be incorporated and existing pipes will be upgraded throughout the project. About 4,300 ft. (1,310.6 m) of asphalt resurfacing will be completed on Highway 14L beginning at Recreation Lane and extending to the north.
Similar amounts of grading and paving are required for both phases of the project, using 30-yd. (27.4 m) scrapers, graders, wheel loaders and packers. There was a lot of soil on site that crews had access to, which reduced the amount that had to be hauled in, but there was waste material (gypsum) from realignment of a service road that needed to be removed.
“A lot of the soil in this area is gypsum, which is waste because it is not very stable and it doesn’t pack well. Over time, water will cause it to erode and it will create sink holes,” Flesner said.
Asphalt from the existing roadways was reused as base material to create a 5-in. (12.7 cm) base on which 9 in. (22.9 cm) of concrete pavement was placed. About 26,000 sq. yds. (21,739 sq m) of concrete pavement was needed and about 6,000 ft. (1,828.8 m) of steel piling.
Moving soil was complicated because of limited space and very rocky conditions. The project required about 150,000 yds. (137,160 m) of rock excavation and 100,000 yds. (91,440 m) of Class X, which is unclassified excafied material.
“The dirt contractor is hoping to get the rocky soil removed with a very large dozer, but the alternative is explosion,” Grangaard said.
“Gypsum is a tough material to remove because it is almost too soft for explosions but it can be too hard to move with equipment, which creates concerns of possibly using explosives. The soil is within 75 ft. (22.9 m) of traffic so we would need help from State Highway Patrol to stop traffic on Interstate 90. The issue is on the northbound berm of the bridge he added.
Once construction is complete, the former southbound bridge will be removed.
“The final component of the project will be the demolition of the southbound bridge and widening the existing northbound bridge to match the newly constructed concrete pavement,” Flesner said. CEG
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