B08_-_Attachment_6_-_ALPO_Staple_Bend_Tunnel_Preservation-1999_CDs.pdf

This document is a set of architectural and engineering construction drawings for the Staple Bend Tunnel Preservation and Visitor Access Improvements project located at the Allegheny Portage Railroad National Historic Site in Cambria County, Pennsylvania. The project is under the auspices of the United States Department of the Interior, National Park Service, with the Philadelphia Support Office managing the work.

The drawings comprehensively detail the preservation and restoration of the historic stone tunnel and associated infrastructure, including site surveys, geologic profiles, tunnel cross-sections, rock bolt and shoring post locations, retaining wall details, foundation specifications, and pedestrian bridge designs. Key project components include tunnel stabilization through rock bolting and shoring posts; construction of new dry-laid stone retaining walls at both portals; installation of a new precast concrete vault lid at the east portal; gateway systems with removable steel mesh panels for seasonal closure; drainage improvements including a membrane system over the tunnel; trail surfacing and layout plans for both base and optional alignments; and comprehensive planting and landscaping plans for both portal areas featuring native deciduous, understory, and evergreen trees and shrubs. The drawings indicate two portal options with associated grading, materials, and detailed construction specifications across multiple sheets, with dates of preparation in July 1999 and supporting documentation including existing conditions surveys, geologic information, and historical photographs.