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Devil's Slide Tunnels
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| Service: | Construction inspection and scheduling for initial and final liner and waterproofing; analysing monitoring data and project's progress; daily site inspection and ground conditions reports.
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| Estimated cost: | Commencement: | November 01, 2007
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Completion date: | March 01, 2011
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| Location: | 585 Linda Mar Boulevard Pacifica, CA 94044 United States |
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| Geology description: | The geological setting comprised quartz diorite, marine sandstone, conglomerate and clay-siltstone. Four main fault zones were encountered. |
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| Bid cost: | Final cost: | $273 million USD
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| Overburden: | ~250m
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| Tunnel length: | 1250m
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Description
Devil's Slide is located south of the City of Pacifica in California along the coastal road of Highway 1. Landslides and grade subsidence in the Devil's Slide area along Route 1 have led to the road being closed for extended periods causing significant economic loss to the surrounding communities. The solution: Construct a tunnel through the mountain to bypass the dangers and reoccurring problems. Construction of 1250m twin tunnels, 9m wide, 6.8m high using Sequential Excavation Method (SEM). Additionally, drill and blast and roadheader excavation through weathered rock utilised.
