The Chesapeake Bay Bridge-Tunnel is a 37-kilometre-long structure of bridges and tunnels for motor traffic in Virginia in the US, which Herrenknecht AG fully excavated with its tunnel boring machine.
Near the city of Norfolk and the adjacent naval base in the US state of Virginia, it connects the Hampton Roads region with the Delmarva Peninsula (part of Delaware, Maryland, Virginia).
A previous bottleneck is now to be eliminated. At the end of January, a tunnel boring machine from Herrenknecht achieved a breakthrough for a tunnel that will contribute to this in the future.
The Chesapeake Bay Bridge Tunnel (officially known as the Lucius J. Kellam Jr. Bridge-Tunnel) has been one of the largest structures of its kind since it opened in 1964.
Bridges and tunnels alternate between four artificially raised islands over a length of 37 kilometers. Four million vehicles a year pass through the bridge-tunnel in a northerly or southerly direction.
Following it opening in 1964, it was named one of the Seven Engineering Wonders of the Modern World.
Schwanau, Germany. Image: Herrenknecht
In 1965 it was awarded the “Outstanding Civil Engineering Achievement”, by the American Society of Civil Engineers. Since 1999, large sections have been widened from two to four lanes: there is a separate bridge with two lanes for each direction of travel.
The Thimble Shoal Tunnel, which passes under a shipping channel, has been a bottleneck. For around two kilometres, traffic is reduced to two lanes, one in each direction, to pass through the tunnel. This is set to change from 2028. The next step is to line the road in the new tunnel.
A so-called Earth Pressure Balance (EPB) shield with a diameter of 13,210 mm, a drive power of 7,000 kW and 46,183 kNm of torque was used.
Herrenknecht’s EPB technology with its earth pressure support is designed for comparatively soft, fine-grained soils and medium earth and water pressures, such as those found when crossing sea floors and rivers at shallow depths.
