It is the second-largest construction project taken on by the S.C. Department of Transportation.
But its impact goes beyond the $231 million price tag associated with improving the Interstate 85/385 interchange in Greenville.
With 220,000 vehicles moving through the interchange each day, S.C. DOT engineer Jack Valetti, the resident construction engineer for the project, said there are a lot of challenges a project of this magnitude faces.
“I think this is one of the most difficult because we are still trying to retain the traffic flow while doing the construction,” Valetti said.
The project ranges in scope from repaving sections of I-85 — northbound from mile marker 35 to mile marker 37 and southbound from Rocky Creek to the Salters Bridge — to traffic light retiming and bridge replacement along the corridor.
Crews with Flatiron-Zachary Joint Venture have already started work on collector/distributor lanes from Woodruff Road to westbound I-385. Valetti said the collector/distributor lanes on I-85 at Woodruff Road will be extended both north and southbound along with the collector/distributor lane being worked on presently.
“The expectation is to get traffic off I-85 to help prevent backups,” Valetti said. “If there is a backup, it can be on the CD lane, not the actual interstate.”
Another aspect of the project will be to augment the traffic light pattern on Woodruff Road from Ketron Court — in front of Costco — to S.C. Highway 14. All 17 signals along that stretch of Woodruff Road will be retimed using a new traffic system.
“We are using an adaptive traffic system and it is supposed to allow the signals to learn from each other based on traffic patterns,” Valetti said. “The system is supposed to adapt so that someone is always moving on Woodruff.”
A traffic study done by the city of Greenville in 2015 pointed specifically to Woodruff Road as a point of issue with regards to traffic lights.
“You have two interstates feeding it and major retail,” said Valerie Holmes, supervisor of the city’s Traffic Engineering Division, in a previous interview with GSA Business Report. “It has really become the retail corridor to be on and it has also become a very congested facility.”
Greenville Police Chief Ken Miller said, at the time of the study, the infrastructure of Woodruff Road, along with other intersections in the city, were an issue because there was no “effective ingress and egress to and from the properties” along Woodruff Road. He said there needed to be a way to get traffic on and off the interstate.
“When it was developed, there was no accounting for traffic, in my estimation. The city has been working hard to figure out alternative routes and there are a few things to relieve pressure on Woodruff,” Miller said.
Another aspect of the project including Woodruff Road is the plan to remove currect access to Woodruff from I-385 and create separate accessibility to Woodruff.
“The car weave from 385 to Woodruff is really incompatible with interstate standards,” Valetti said. “There would still be access from I-85 to Woodruff. It is really the only way we could really improve the interchange.”
As for Woodruff itself, the plan is to reconstruct the Woodruff Road intersections at Miller/Garlington, Carolina Point and Market Point. Valetti said the reconstruction will allow for better traffic flow and include additional turn lanes.
The state also plans to add a westbound lane of Woodruff Road from I-385 to Carolina Point.
Other parts of the interchange project include widening I-385 from four to six lanes and eliminating the tight loop ramps from I-385 to I-85. Instead of the loops to merge, the state is constructing flyovers. Valetti said the flyovers will be 1,950 feet long and 1,700 feet long, approximately.
“You will be able to keep your speed moving at a constant,” Valetti said.
S.C. DOT is replacing all 11 bridges that are part of the interchange. This includes adding the replacement of the bridge over Garlington Road. Initially, the state planned on just resurfacing that bridge, but Valetti said the contractor price was advantageous to allow for complete replacement. The replacement price tag of that bridge was an additional $5.3 million.
“That will give us all new structures on the interchange,” Valetti said. “We won’t have to come back in five years and fix something.”
However, adding the replacement of the Garlington Road bridge added 70 days to the completion date. Another hiccup was that the acquisition of a permit added another 150 days, moving the completion from October 2018 to May 2019. Other delays included the redesign of I-85 over Rocky Creek because of a higher flood elevation for the creek. The redesign included the addition of retaining walls and adding flood warning signs.
A permanent solution to the issue is being looked at as part of the future I-85 widening project expected to start in the early 2020s.
Overall, Valetti said there has been a significant amount of work done on the project, even though it may not seem like it.
“We are a year into it and there is still a lot of work to be done,” Valetti said.
The project is being funded by Act 98 of 2013 which gave S.C. DOT additional funding for interstate projects, the Federal Highway Administration and the Greenville-Pickens Area Transportation Study Committee.
Editor's Note: The story was corrected to reflect that the acquisition of a permit added 150 days to the project.