ISI provided special inspection and materials testing services for the century old Twin Peaks Tunnel in San Francisco. The project consists of major improvements and seismic upgrades, which includes, a full track replacement, replacement of the tunnel drainage system, new fire suppression system at West Portal station, and seismic upgrades at the eastern end of the tunnel. These extensive improvements to the tunnel ensure it can continue to safely transport the 80,000 daily riders through the 2.25 mile tunnel for years to come.

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    2019 – 2020

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    Construction Value

    $40 Million

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    San Francisco Municipal Transportation Agency

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