Project Description

In 1992, Lachel & Associates inspected, developed an investigation program, and performed a constructibility analysis for the rehabilitation of an abandoned railroad tunnel in the Corliss neighborhood of Pittsburgh, Pennsylvania.

The Cork Run Tunnel (also known as Tunnel No. 2) was originally constructed in 1865 as a single track railroad tunnel. In 1873, the tunnel was widened to accommodate dual railroad tracks. The tunnel opening was a semicircular horseshoe arch with a width of 25 feet and a height of 21 feet. The deteriorated tunnel lining was comprised of multiple layers of brick and mortar with an overall thickness of roughly 24 inches. The length of the tunnel was approximately 2,400 feet.

Scope of Services

Lachel & Associates, Inc. developed tunnel rehabilitation alternatives to convert the tunnel into a dual lane dedicated bus transit tunnel. All of the alternatives included increasing the tunnel width and lining strength, as well as improving the watertightness of the tunnel. Lachel performed a full tunnel inspection prior to developing a tunnel investigation program to assess the structural integrity of the existing tunnel lining. The investigation program included drilling numerous coreholes through the lining to assess the condition of the lining, presence of voids, and the rock quality beyond the lining. Lachel reviewed the results of the investigation program and tailored the rehabilitation alternatives to suit the existing site conditions. Lachel assisted HDR in development of structural reconfigurations of the lining and the sequence of construction. Alternatives involved installation of a polyethylene waterproofing system, grouting of existing voids behind the existing brick lining, and placement of a fiber reinforced shotcrete lining. As part of the constructability evaluation, Lachel provided detailed cost estimates for performing the rehabilitation work.

Client

HDR Engineering, Inc.
Dick Corporation
Pittsburgh Transit