I-77, a north-south highway, runs from the center of the state of South Carolina to North Carolina and beyond. In 2021, the average daily traffic count for I-77 in the area where the interchange is being constructed was just over 88,000 vehicles. I-77 is a commuter route to Charlotte, which is just 25 miles away.
The active area is home to two industrial parks – both on the east side of I-77. One of the industrial parks, Riverwalk Business Park, has no direct access to I-77. There are a sizable number of trucks going to and from the industrial park, yet their only access to the facility was a secondary road.
“We expect the interchange to remove truck traffic from the secondary roads enabling the commuter traffic to have better access and less congestion,” says Pete Poore, Director of Communications for SCDOT. “The interchange will improve the potential for development on both sides of I-77, particularly the east side where there’s not much development on one side.”
The Catawba River spans 200 miles and runs through Carolinas, including York County. The river gets a lot of recreation use, including tubing and kayaking in Rock Hill. The interchange will provide alternate access to the river and will also provide access to Fort Mill, another city in York County.
“The team elected to use a single span bridge to avoid construction of a bridge pier in the I-77 median which would have caused significant delays due to lane closures that would have been required to execute the work.” says Poore.
The team installed 5,575 feet of barrier wall along I-77 to protect workers and to protect the traveling public from coming in contact with construction materials, equipment, and activities. It also allows work to continue during daylight hours without intermittent lane closures. “We do this, or something similar, on most interstate jobs due to high speed and volume of traffic to allow work to more safely be accomplished close to traffic,” says Poore.
A queue detection and warning system are also being temporarily installed. It sends messages to drivers to alert them about conditions in the project area. The portable electronic message boards use real-time traffic sensors and send warnings to drivers about congestion and delays when appropriate.
This arrangement was helpful for this project because one of the unsuccessful proposers (not the best-value bidder) had a design plan element that SCDOT requested the successful proposer to incorporate into the final project design.
The original interchange concept impacted a stormwater detention pond for a large commercial property on the east side of I-77. The cost and scheduling implications to relocate this pond were significant, therefore SCDOT incentivized design-build proposers to minimize impacts on the pond through the use of quality points in the best-value award formula.
“One proposer, through the use of an Alternative Technical Concept (ATC), modified the location of the northbound I-77 off-ramp to bridge over the northbound loop ramp eliminating impacts to the detention pond,” says Jae Mattox, the Alternative Delivery Engineer for SCDOT.
SCDOT was able to incorporate the ATC into the winning bidders’ proposal and experienced a project savings of over $6 million.
Another challenge the team faced was installing the 214-foot-long girders for the bridge. The team used two 440-ton cranes and one 150-ton crane to hand off the 214-foot-long, 9-foot-wide girders in mid-air. The girders were installed in this fashion to reduce the construction time. “Much planning went into installing the lengthy girders, so the process went smoothly,” Poore says.
UBPJV was specifically assumed to access local design and resources to self-perform all development with a highly accelerated schedule. “United Infrastructure Group is located in the area and has worked with the SCDOT for years,” says Poore. “The team scored the highest in our selection process. Both companies have significant design-build delivery experience in the Carolinas and have been valuable partners with SCDOT.”
The budget for the project is just under $81 million. Financing for the project is coming through multiple vehicles, including a federal infrastructure grant ($34.6 million), the South Carolina Coordinating Council for Economic Development ($40 million), GT Real Estate Holding ($5.3 million), and the city of Rock Hill ($1 million).
The project began in the fall of 2021 and is scheduled to be complete in May 2023. As noted above, the project is being constructed via the design-build method. “SCDOT has had success with design-build as it typically leads to a cost and time savings,” says Poore.
So far, the method is proving successful on this project too, as it is on budget and schedule.
Upon completion of the interchange, the area will have greater access to multiple facilities. Congestion will be relieved on the secondary roads, which enables better access for everyone.