Work began on Exit 60 at Rapid City, SD, in April 2005 by primary contractor, Heavy Constructors Inc., of Rapid City, with a price tag of $17 million.
“The pavement and bridges were in poor shape. The concrete base was overlaid with asphalt several times and the ramps were substandard,” said Kevin Howland, project manager of the South Dakota Department of Transportation.
The bridges were built in the early 1970s and carry a 25- to 30-year design life. “Now we shoot for a 50-year length,” he said.
Traffic can now enter or exit I-90 from exit 60 in both directions.
The project required the removal and reconstruction of eastbound and westbound I-90 between LaCrosse Street and approximately half-way between Dyess Avenue and Elk Vale, Howland said.
East North Street also will be reconstructed from just east of Campbell Street to north of I-90 up to the new Mall Drive intersection and will go under the new eastbound and westbound I-90 bridges at the exit 60 Interchange.
The interchange will provide access to and from the newly constructed East North Street, which will be reconstructed from just east of Campbell Street to I-90, continuing under the interstate to Mall Drive north of I-90, Howland said. A section of Mall Drive also will be constructed between East North Street and Dyess Avenue.
Also included in the project is the installation of utilities and the construction of Mall Drive north of I-90 between the new extension of East North Street and Dyess Avenue.
Currently the project is approximately 70 percent complete, Howland said. Work for this construction season began in March and workers are now constructing the base for the new eastbound I-90 lanes and the reconstruction of Highway 16B’s northbound lane.
“We’re now placing a gravel cushion for concrete pavement on East North Street,” Howland said. “Work is not quite finished on I-90; there is still some storm sewer to put in.”
Traffic is head-to-head on East North Street while the north bound lane is being worked on between Campbell Street and Anamosa. Traffic will switch to head-to-head in the newly built westbound lane.
Work on the bridges presented some challenges, he added.
“When we were ready to start last summer, we ran into a tremendous amount of unsuitable materials underneath the bridges.”
After excavating several feet down, using several backhoes, including a 375 trackhoe and 950 loaders, the area was filled with rock followed by several layers of fabric and then another 6 to 7 ft. of rock and more fabric, to stabilize the soil so the equipment could be brought in to construct the retaining walls, Howland said.
“This caused the project to fall behind but we still anticipate finishing by the July 28 completion date. Some phases of the project are behind while others are ahead of schedule. Overall we are still on target.”
The interstate will consist of 12-ft. driving lanes, two in each direction, acceleration and deceleration lanes, which have been widened, 10-ft. outside shoulders, which also are wider than they were previously.
On East North Street, there will be two 12-ft. lanes plus a center turn lane that will run continuous between Campbell and I-90. A 28-ft. paver was used to accelerate the project.
The interstate was raised and lowered in some areas, with the help of Caterpillar 651 scrapers and D9 and D10 dozers, so both lanes will now be at the same elevation, Howland said.
Most of the concrete pavement from I-90 was recycled and placed in the deep fills outside the highway, saving money on the project and for the contractor, Howland said, which also kept the landfill from being filled. The removal of the unstable material caused an approximate $400,000 overrun on the project.
Before the project was put on hold for winter, temporary asphalt was placed last December in some extremely cold temperatures, Howland said.
“We wouldn’t normally place asphalt in five-degree temperatures but it allowed us to get the roadway open before Christmas. We were about a week late in meeting our December 2 deadline,” — because of the subzero temperatures.
The construction season is normally wrapped up before the colder temperatures strike, but the past few winters have been fairly mild, causing the season to get stretched out, he commented.
“The season is getting longer and workers are trying to get more done during the good weather before the bad weather hits and shuts you down,” Howland said. CEG
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