By rosebell
In order to completing the second of the twin-bore tunnels beneath the Hampton Roads Harbour, marking the end of 29 months of tunneling, TBM Mary broke through at the South Island .
The attendees of the ceremony of this achievement were tunnelling crews, Governor Glenn Youngkin, US secretary of transportation Sean Duffy, Virginia secretary of transportation Shep Miller, Virginia Department of Transportation (VDOT) commissioner Stephen Brich and other VIPs and guests.
While the date of commencing excavation of the second tunnel was October 17, 2024, it was completed three weeks faster than the first 2.41km-long bore.
Although TBM Mary’s 14m-diameter cutterhead has broken through the diaphragm wall, six more concrete rings requires to be installed to complete the tunnel construction.
Hampton Roads Connector Partners , which is a consortium of Dragados USA, Vinci, Flatiron Constructors, and Dodin Campenon Bernard, is the project’s design-build contractor and as a world record for a machine of TBM Mary’s size, it marked several milestones during tunneling, including a more than 111.5m progress in a single week.
TBM Mary was turned 180 degrees using nitrogen skates following completion the first bore, and made the first time thst this method had been used in the US.
According to US transportation secretary Sean P Duffy: “The final breakthrough demonstrated “what’s possible when collaboration meets innovation to build big, beautiful infrastructure.”
While the scheduled date for inaugurating the tunnels is 2027, the HRBT is the largest highway construction project in Virginia’s history.
