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Tunnel boring machine 'Mary' officially unveiled for HRBT Expansion Project

The machine, when reassembled, will roughly be the same height as a four-story building.

PORTSMOUTH, Va. — A new arrival is paving the path ahead for what James Utterback hopes means less headaches for drivers in Hampton Roads. 

“Traffic should move a lot better than it does during peak times," Utterback laughed, the Project Director for the HRBT Expansion Project. 

Tuesday, state and transportation leaders officially celebrated the arrival of the tunnel boring machine 'Mary' to Virginia, a mammoth excavating machine that will dig the tunnels for the expansion of the Hampton Roads Bridge-Tunnel. 

With a price tag of $3.8 billion, the HRBT Expansion Project is the largest highway construction project ever in Virginia.

“This machine does two processes simultaneously," Martha Gross said, the Technical Director for the HRBT Expansion Project with the Virginia Department of Transportation. "The cutter head turns and excavates the soil, the second process is a robot arm installing pre-cast concrete shell segments behind the cutter head of the TBM, to hold the soil open so that when the TBM  moves forward the tunnel stays open.”

While 'Mary' has arrived in the commonwealth, Tuesday's unveiling was more ceremonial in nature, with the curtain revealing a scaled-down model of the machine. The Tunnel Boring Machine is currently deconstructed among 170 components and will take approximately the next six months to put together. 

Once completed, transportation officials say they expect tunneling to begin sometime in mid-2022, the beginning of a years-long journey to reduce congestion from the Peninsula to the Southside.

“Peak summer hours we see traffic at about 100,000 vehicles per day," Utterbank said.

Here are some other statistics about Mary:

  • When reassembled, the machine will be 46 feet tall and more than 430 feet long, weighing more than 9 million pounds. 
  • Will move roughly 50 feet per day
  • Powered by 12 electric motors totaling 12,000 horsepower 
  • Maximum torque in 36 million foot-pounds

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