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Phase 3 Project Details (Tunneling)

Update 17 December 2018
: In order to construct the Coming St access/retrieval shaft, the King St ramp from I-26 eastbound will be closed for the duration of the project, estimated to be July 2019.  
Click here for a link to the map showing alternate routes.  


  • Shaft construction is almost complete and excavation of the President Street tunnel continues.  
  • Complete work at Lockwood St Shaft Site:  January 2019
  • Substantial Completion:  Spring 2020
  • Final Completion: Summer 2020

Phase 3 of the US17 Spring/Fishburne Drainage Improvement Project will include the construction of deep tunnels and working shafts. There will be 4 working shafts constructed as part of this phase. Two of the shafts will be 20-ft internal diameter (Coming Street/King Street off-ramp and President St & Cannon St). The wetwell shaft between the Ashley River Bridges and the Harmon Field working shaft will be 30-ft internal diameter. The tunnel connecting the Coming Street shaft and wetwell shaft (under the Crosstown) will be approximately 5,400 LF (linear feet) in length and up to 12-ft in internal diameter. The tunnel connecting the Cannon St/President St and the Harmon Field shafts will be approximately 2,100 LF in length and a minimum of 8-ft in internal diameter. These tunnels will intersect approximately 140 feet below grade at the intersection of the Crosstown and President Street. There will also be a smaller 500 LF 8-ft diameter tunnel connecting the Cherry St drop shaft to the Crosstown tunnel.  

For videos of the mainline tunnel, click here  and here.  

Note:  Completion of the work at the Lockwood St shaft site is significant as that will allow the commencement of Phase 4 of the project, construction of the wetwell and outfall.

The videos below were taken during placement of the tunnel boring machine (TBM) in the Lockwood Drive working shaft and are courtesy of Upwind Studios of Mount Pleasant, SC.  

Lockwood Drive Shaft

Lockwood Drive Shaft Orbit

TBM Insertion Timelapse