Home Front end Boring HRBT extension? Yes and no

Boring HRBT extension? Yes and no



December 31, 2021


Elizabeth cooper

The HRBT tunnel boring machine was assembled in Germany for a factory acceptance test before shipping to the USA Photo courtesy of Herrenknecht AG

Already the largest project yet to be tackled by the Virginia Department of Transportation, the $ 3.8 billion expansion of the Hampton Roads tunnel bridge will kick off later this year when a custom-built 70 million tunnel boring machine (TBM) dollars will begin to plot an underwater path for the twin two-lane tunnels.

Construction of the HRBT extension, which will increase the capacity of tunnels and roads along the 9.9 miles of Interstate 64 between Hampton and Norfolk, began in October 2020 and is expected to be completed in November 2025.

This is only the fourth time that a tunnel boring machine will be used on a US highway project, including tunnels in Seattle, Miami and the Parallel Thimble Shoal Tunnel under construction in the nearby Chesapeake Bay Bridge Tunnel.

The height of a four-story building and measuring the length of a football field, the front end of the tunnel boring machine consists of a 46-foot diameter rotating cutting head that pierces soil and rock strata creating an opening approximately 45 feet wide for the new tunnels. Virginia Beach college students nicknamed the machine “Mary” after Mary Winston Jackson, the late NASA mathematician and aerospace engineer portrayed in the 2016 film “Hidden Figures.”

Hampton Roads Connector Partners, a joint venture led by Dragados USA Inc., is the design-build team for the project. It commissioned German company Herrenknecht AG to manufacture the drilling rig, which arrived at the Port of Virginia on board three ships in December. Crews have prepared a 70-foot-deep launch pit on the South Island near Norfolk where the tunnel boring machine will be assembled and ready to begin excavation by mid-2022.

“We are actively working to prepare the launch pit,” says James Utterback, VDOT’s project manager for the HRBT expansion. “It’s a big project that contains a series of big projects and a lot of unique construction operations that need to come together. ”

Once underway, a hydraulic jack will move the tunnel boring machine about 50 feet per day as the cutterhead digs a two-lane tunnel to North Island near Hampton, a process expected to take about a year. On North Island, it will take 4-6 months to run the machine on a specially constructed turntable for its return trip, drilling a two-lane parallel tunnel to South Island. The return trip is expected to take 10 to 12 months, with the total process taking around 2½ year.