While the life of the concrete was extended, SDDOT determined that a more thorough repair was necessary as the stretch of I-90 was reaching the end of its life cycle. The new concrete was reconstructed as a part of the program to replace the highway. The new concrete driving surface is 26 feet wide by 12 inches thick. It has an 8-inch-thick by 6-foot-wide concrete median shoulder and an 8-foot-wide asphalt concrete shoulder on the outside. This project focused solely on the westbound lanes; SDDOT will focus on the eastbound lanes in 2024.
In addition to removing and replacing the concrete, two bridges were removed. One bridge was replaced with a slightly taller and wider bridge to enhance safety. The new bridge has wider shoulders, which allow for a stalled vehicle to be on the shoulder and out of the travel lanes. This also helps traffic flow.
“The bridge had been hit several times by over height vehicles,” said Harvey Odens, an Engineer for SDDOT. “The increased height allows for more clearance underneath for the SD-19 traffic.” The new bridge clearance is approximately 2.5 feet higher.
Another bridge, which was over a creek, was replaced with a triple 12-foot by 12-foot barrel box culvert.
This section of I-90 has a relatively high volume of traffic (an average of 6,500 daily vehicles) due to its vicinity near Sioux Falls. The team moved all the traffic on the eastbound lanes, making a 13-mile two-way road with no passing. Exit and entrance ramp traffic was maintained at two interchanges in that stretch with temporary ramp crossings through the work area.
The contractor set up their mobile concrete production plant near the center of the project. The area where they located the plant had been an alfalfa field. Reede leased the land from a farmer and accepted the obligation to restore it to its original condition after they completed the project.
Having a fully functional concrete plant in the center of the project drastically shortened the delivery time. “The construction season in this part of the country is shorter due to weather limitations,” Odens said. “Reede’s decision to put the concrete production plant onsite helped keep the project on schedule.”
The reduced amount of travel adds a green component as it means less fuel usage. The onsite concrete production plant also cut down on trucking costs and minimized the challenge of working with concrete, which must be poured within a limited time.
At the plant, Reede used a resonant pavement breaker that turns the concrete pavement to rubble. The reinforcing steel inside the pavement can then be pulled out, and the broken concrete is then put through the mobile crusher.
“The rubblized concrete is put through the mobile crusher, which breaks it down basically into a salvaged gravel that is then mixed with the dirt undercut and used for constructing the new road base,” Odens said. “This produced a very stable road base for placing the gravel cushion and constructing the new concrete surfacing.”
Odens credits the contractor. “They monitored all aspects of project work and were able to complete the project on time,” he said.
Another significant factor for the on-time completion was the weather. There were very few weather delays during the summer construction season.
The contract for the project was $35.7 million. Funding for the project was divided between the federal and state governments, using the traditional 80/20 percent split. The project was completed on budget.
With the new concrete on this section of I-90, drivers have a smoother ride on a road built to the current design standards. The new pavement depth is 12 inches, which will help with pavement life extension and durability for the high traffic volumes and increased load size of the many trucks that travel the roadway. The speed limit in the area is 80 mph, and the new concrete will accommodate the greater speeds of traffic. The wider and taller bridge also enhances safety for commuters.