I-40 PIGEON RIVER GORGE: LARGE SCALE EMBANKMENT RECONSTRUCTION IN THE HURRICANE HELENE AFTERMATH-PPT Presentation

PPT Presentation

Pdf Summary

The presentation outlines NCDOT’s reconstruction of five miles of I-40 through the Pigeon River Gorge following Hurricane Helene. The project was divided into seven sections to manage differing conditions, access, alignment, and damage. Three miles of linear roadway are being rebuilt with roller-compacted concrete (RCC) buttresses, while interlocking pipe pile (IPP) walls are used for two miles of curved or top-down construction areas.<br /><br />Key lessons from the storm include the need to distinguish bedrock from boulders, prevent water from getting behind or beneath structures, account for debris impact and drag, and design for scour and rapid drawdown. Variable rock conditions require flexibility during construction. Feasibility is also shaped by the need to reopen a critical roadway quickly, limited access in a narrow active corridor, and opportunities to reuse existing materials.<br /><br />RCC offers fast construction on linear sections and has a track record in hydraulic settings, but it requires substantial hauling and material sourcing and may involve dewatering. IPP walls provide structural capacity, resilience, reduced river encroachment, and lower drilling risk, though they take longer to install.<br /><br />Three IPP areas use 36-inch piles with 15-foot rock sockets and tiebacks. Their configurations differ to address site conditions, including top-down construction where part of the embankment remains and bottom-up construction where slopes or lanes have been lost. The presentation also highlights toe-treatment options and stresses adapting designs to conditions encountered during construction.

Keywords

NCDOT

I-40 reconstruction

Pigeon River Gorge

Hurricane Helene

roller-compacted concrete

interlocking pipe pile walls

bedrock and boulder distinction

scour and drawdown

top-down construction

tieback walls