The new tunnel at the Chesapeake Bay Bridge Tunnel will be created using a massive, million-dollar tunnel-boring machine (TBMs). These machines use a circular plate with disk cutters that rotate to cut through rock, muck or sand as it inches forward slowly. As the machine excavates the tunnel, it also helps to build the walls that will eventually support the tunnel.
France and England used 11 massive TBMs to create the three tubes that make up the 32-mile Channel Tunnel. Also called the Euro Tunnel or Chunnel—it took three years to dig those tunnels.
Dragados USA, which operates in 68 countries, has partnered with Schiavone Construction Co. to construct the tunnel. Dragados has built more than 800 miles of tunnel, 5,200 miles of highway and 1,500 bridges and is currently building a large bored tunnel in Seattle. Schiavone has built several subway lines in New York City.
A large pit will be opened 105 feet below the water on the island nearest Virginia Beach. The boring machine will be shipped to the site and assembled at the bottom of the pit.
The machine’s 41-foot rotating head cuts into the soil, carves it out and hauls it away on a conveyor belt before it’s transferred to trucks. Precast concrete tunnel segments are loaded into the machine and pushed into place. Once one ring of concrete is finished, the machine pushes forward, excavates more soil and adds another ring. When it reaches the other side, the machine will be disassembled and removed. Then crews install the roadway, lighting and mechanical systems.