Tunnels of the Pacific Railroad
Year: 1870
By John Gilliss, C.E.
Gilliss surveys every tunnel completed or underway on the newly finished trans-continental route, focusing on the Central Pacific’s granite Sierran bores. For each tunnel he tabulates location, length, altitude, geological formation, excavation method (hand drill vs. nitro-glycerine & compressed-air drills), timbering details, daily progress rates, labour costs, and final lining. He discusses winter snow-sheds, ventilation problems, and the logistical challenge of delivering explosives and ironwork over primitive wagon roads. Concluding sections compare American practice with Alpine experience and suggest design standards for future western rail tunnels. The paper served as a technical benchmark for railroad tunnelling in hard rock.
