Gall Zeidler Consultants developed a feasibility study for the reconstruction of the existing Old Union Railroad Tunnel to allow for an increase of the tunnel clearance envelope. The study called for existing tunnel linings and portions of the surrounding ground to be removed.
Tunnel Reconstruction Feasibility Study:
Gall Zeidler Consultants proposed a mined option for the reconstruction of the majority of the tunnel and a modified cut-and-cover construction method (top-down) for the portal areas. The proposal also called for a flexible membrane waterproofing system installed between initial shotcrete and final cast-in-place concrete linings. The waterproofing system consisted of a PVC membrane over a geotextile material.