Cliffs Highway Tunnel
The Cliffs Highway Tunnel project near Swannanoa, North Carolina was being developed to facilitate vehicular access into a new planned community. The project consists of a 600-ft long, two-lane tunnel to be excavated in hard rock using drill and blast methods.
From the conceptual stage through final design, Lachel collaborated with its sister company Schnabel Engineering Consultants (Schnabel) in the design of the project. Schnabel led a phased geotechnical investigation effort consisting of geologic mapping, a drilling and laboratory testing program, packer permeability testing, and geophysical surveying. Using early field investigation results, Lachel first developed a conceptual design including ground support and construction sequencing for the portals and tunnel. In coordination with our fire and life safety subconsultant, all ventilation, lighting and fire protection requirements were assessed. Based on the conceptual design, Lachel developed a budget level cost estimate for the project. Together, the geotechnical information, conceptual tunnel and portal designs, and cost analysis were presented to the project owner resulting in a decision to proceed to final design.
During final design, Lachel incorporated the results of a detailed rock discontinuity analysis and the numerical analysis of rock loads and deformations into selection of the final ground support classes. Lachel developed the contract drawings, technical specifications, Geotechnical Baseline Report (GBR), and the final Opinion of Probable Cost. Lachel also developed various portions of the front-end contract documents and assisted the owner during the bid phase of the project.