Tunnel Boring Machine (TBM)
Pictured above: model of TBM that will bore the new twin tunnels at the HRBT
The Tunnel Boring Machine (TBM) is the technology to be used to bore new twin tunnels next to the existing Hampton Roads Bridge-Tunnel. Hampton Roads Connector Partners (HRCP), the project's joint construction venture, awarded a contract to Herrenknecht of Germany for construction of the TBM. It will take approximately 14 months to build the 46-feet-high machine, approximately four months to ship it from Germany, and another four-to-five months to assemble the TBM on the HRBT's South Island in a 65-foot pit.
The TBM is longer than a football field. As you can see from the picture of the TBM's cutterhead (pictured below), the machine is about the height of the HRBT Project Office, which is a four-story building. The price tag for the TBM alone is $101 million which includes construction, shipping and assembly costs.
Pictured above: Scale of the TBM next to the HRBT Headquarters
The TBM will launch from the South Island (Norfolk side), and bore (work) at a rate of about 50 feet per day until it reaches the layer of soil known as the Yorktown layer, approximately 50 feet below the current tunnels. The TBM excavates the tunnels with a circular cross section through the soil. The process will take more than two years. Built specifically for the HRBT Expansion Project, the TBM will be a central component of the project.
The existing ten tunnels in Hampton Roads are immersed tubes. Advances in tunnel technology make the bored-tunnel approach desirable for the expansion project. The method has fewer environmental impacts and does not disrupt Navy, marine, or commercial traffic in the busy federal channel.
Tunneling is expected to begin in early 2022.
Pictured above: TBM under construction at Herrenknecht in Germany
TBM Naming Contest
She's Big. She's Bold. She has a Name!
The HRBT Expansion Project held the Tunnel Boring Machine (TBM) Naming Contest in the fall of 2020. The contest was open to middle school students in Hampton Roads. First place winner of the contest was Saint Gregory the Great Catholic High School in Virginia Beach with the name, "Mary the TBM" in honor of Mary Jackson of Hampton, VA – mathematician and aerospace engineer at NASA, noted for her pioneering role of an African American woman in the field of science and engineering, and her crucial contributions to the NASA Space Program. The winning name, "Mary the TBM", will be printed on the TBM that will bore the new twin tunnels at the Hampton Roads Bridge Tunnel. Read more...