Washington Metro expanding tunnel waterproofing (Global Rail News)

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A project to reduce water infiltration in deep segments of the Washington Metro’s Red line has been expanded. An initial pilot began in July, 2017, with contractors installing a new waterproof membrane on sections of the Red line.

These were built before the widespread use of the New Austrian Tunnelling method – which provides a tunnel with a waterproof membrane – go below water level and are prone to leak.

The pilot involved using a “curtain grouting” technique that requires drilling hundreds of holes through the tunnel ceiling and injecting a polymer-based material through the holes to form a protective layer on the exterior of the tunnel walls.

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Written by Long Branch Mike