Excavation of Virginia’s first-ever bored road tunnel completed

It was recently announced that a tunnel boring machine (TBM) named Mary made its final beak through on April 17 for the first bored road tunnel in the history of the state of Virginia.

Furthermore, the tunnel is part of the Hampton Roads Bridge-Tunnel Expansion (HRBT) project, which includes the twin bored road tunnel section among others.

The broader HRBT project was given the green light from the Virginia Department of Transportation (VDOT) in 2020, while it is the state’s largest highway construction project ever.

HRBT is expected to be completed in 2027 and cost a total of $3.9 billion, aiming to widen the 16 kilometers of four-lane segments along I-64 between Norfolk and Hampton.

The TBM, Mary, was launched from South Island in April 2023 and took a year to complete its 2.4 km (7,900 ft.) journey to North Island, excavating 573,400 m³ (750,000 cubic yards) of soil along the way.

Moreover, $70 million custom-built Mary measures 46 feet (14 m) in diameter and 430 feet (131 m) in length and installed 1,191 concrete rings along the tunnel, achieving a maximum pace of excavating 113 feet and laying 17 rings within a day.

The new tunnel is positioned about 50 feet deeper than the already existing one, reaching a maximum depth of 173 below the water surface, white the existing tunnel was completed in 1957 and was the world’s first tunnel between two manmade islands.

HRBT’s pre-existing tunnels were of the immersed type, along with most road tunnels that have been constructed so far in Virginia.

Namely, RBT Expansion project director, Ryan Banas, stated that at this time only two bored roadway tunnels are in existence in the US, one in Seattle and one in Miami.

Finally, it will now take about six months to turn Mary around, and roughly a year for the excavation of the twin tunnel's second tube.