SCDOT reps explain $2.35 billion I-526 Mark Clark Extension cost

Published: May. 5, 2022 at 8:32 PM EDT|Updated: May. 6, 2022 at 4:18 AM EDT
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CHARLESTON, S.C. (WCSC) - On Thursday night, three representatives from the state department of transportation presented an updated plan to Charleston County Council for the I-526 Mark Clark extension.

The project would build nine more miles of interstate stretching from West Ashley through Johns Island and onto James Island.

Secretary of Transportation Christy Hall sent a letter estimated the cost to be about $2.35 billion to the county council last week. She says her team did a lot of work, considering a variety of factors that all make up the estimate.

“That layering is what led up to the 2.35 billion. So, a base we generated, applying factors of risk and other inflation factors type things. Again, forecasting that this is going to come to market 2026 to 2027 time frame for phase one,” Hall said.

This estimate is based on the DOT’s internal investigation.

They say it involved a base material and last cost, projected contracted labor and some potential risks.

“So we tried to determine the likelihood of that risk occurring. And we did this hundreds of times with hundreds of different issues. And then we ran this simulation that simulated the project tens of thousands of times and it basically came up with the 2.3 billion in all the different scenarios as the likely cost – the cost it would not exceed. So that cost or below.”

A DOT rep explained a lot of the reason the reason the cost went up is inflation.

The new estimate triples a cost estimate from 2014.

“Basically, market conditions and inflation. I mean we all know things cost more than they do in 2014. A lot more. In addition, we took a harder look at right of way. A lot has changed in the project area. Right of way cost property values have skyrocketed,” the representative said.

After presenting the findings, the DOT representatives recommended the council proceed with the project.

District seven councilman Brantley Moody agrees it needs to move forward.

“I think that in five years it’s going to be 4 billion and in 10 years it’s going to be 10 billion. So the prudent thing is to move this thing forward and get it shovel ready. The need has never changed, the need is only getting worse,” Brandley said.

Other council members are deterred by the cost, saying it’s getting to be out of hand.

“That’s certainly beyond the scope, in my opinion, of what county council can tackle. We decided by contract a number of years back that we the county were going to take the bull by the horns on this thing and we were going to handle it instead of DOT. I think that was a tragic mistake by us,” Councilman Dickie Schweers said.

“That is astronomical 287 million dollars a mile. I don’t understand that, I really don’t, so my vote is not going to be speculative, my vote is going to be no. This is just too much,” said Councilman Henry Darby.

The DOT ended the visit by asking the council to consider authorizing 150 million from the county and the state infrastructure bank split equally, for the rest of the preliminary work, before proceeding with the project. The estimated cost of phase one construction is $1.35 billion and the estimated construction cost for phase two is $702 million.

A breakdown of the cost increase from the presentation is as follows:

  • Base material costs/quantities and labor increases: + $700 million
  • Mobilization increases: + $59 million
  • Bridge structure/complexity increases: + $63 million
  • Additional sound barrier walls: + $8 million
  • Traffic control/lighting cost increase: + $11 million
  • Misc. unit price and quantity increase: + $57 million
  • Additional contingencies: + $76 million
  • Project delay costs: + $112 million

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