Sunday, February 5, 2023

Tunnel Boring Machine Makes Its Long-Awaited Debut

The segments of Mary the TBM have arrived in Hampton Roads and will be reassembled over the next six months. (Courtesy of VDOT)

NORFOLK — After months of anticipation, the Tunnel Boring Machine (TBM) named “Mary” arrived in Norfolk on Dec. 14. The TBM will be responsible for digging the tunnels for the Hampton Roads Bridge Tunnel (HRBT) expansion project

“Mary,” which was named in honor of pioneering NASA engineer Mary Winston Jackson, was manufactured in Germany and shipped to Virginia in 170 different parts on three separate vessels.

When it is reassembled by mid-2022, the TBM will be 46 feet tall, 430 feet in length, weighing over 4,700 tons. To put it in perspective, that is roughly the same weight as ten fully loaded Boeing 747s.

“Today, we welcome ‘Mary the TBM,’ the most advanced boring technology in the world, to the Commonwealth of Virginia,” Secretary of Transportation Shannon Valentine said. “We remain committed to bringing every asset to the table to give the people in this region what they value most — time.”

Once assembled, the TBM will take around a year to finish boring from South Island, moving towards the North Island at a rate of up to 50 feet per day. Once Mary reaches North Island, it will take four months to turn it around followed by another year digging a tunnel back to the south island.

State, regional and project officials, along with students from St. Gregory the Great, unveil a model of Mary the TBM. (Courtesy of the Virginia Department of Transportation)

Each tunnel will be about 8,000 feet long, and the deepest segments will be about 150 feet below the water’s surface. The new tunnels will be about 50 feet deeper than the existing tunnels.

The project has a price tag of $3.8 billion and is projected to increase tunnel and interstate capacity along ten miles of Interstate 64 between Hampton and Norfolk.

Along with improving traffic flow, the project is expected to create 28,000 jobs and generate $4.6 billion in economic impact.

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