This brief history and discussion of the tunnel, construction methods, costs and time durations, also reviews contemporary tunneling technology and details the specific activities at the tunnel. Geologic mapping immediately after excavation revealed that bedrock from the east end to beyond the central shaft was micaceous gneiss or schist. Rock foliation dipped generally to the east. The west-central portion contained gneiss or granitoid gneiss and the mountain was intersected with hard seams of quartz. Conditions at the west end were complicated by a thrust fault. The cost of the tunnel is estimated to be approximately 14 million dollars. It is suggested that, if constructed today, the tunnel would be shorter, larger in cross-section, and built without shafts. Ventilation during construction would be by pies or conduits within the tunnel. Drill and blast procedures for excavation will not be very different from those originally used. It is estimated that today it would take 3-1/2 years to construct and cost $75,000,000 for a full double-track cross-section.

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Filing Info

  • Accession Number: 00148643
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Mar 30 1977 12:00AM