When Boring is Not Boring...

We recently traveled down to OBX for vacation and had the opportunity to traverse one of the engineering wonders of the modern world - the Chesapeake Bay Bridge Tunnel in Virginia. This 17.6-mile bridge and tunnel complex was built in 1960 and spanned the lower Chesapeake Bay connecting Virginia's Eastern Shore to the Virginia Beach mainland. Construction took 42 months and carries millions of drivers up and down Route 13 north and southbound.

In 2017, a Parallel Thimble Shoal Tunnel Project was started using private funding to add a second bridge and underwater tunnel system to the existing span. Once complete in early 2028, this addition will allow drivers to travel southbound on the newer bridge and tunnel and northbound on the existing bridge/tunnel system.

So when is boring (mining) not boring?

Introducing Chessie - Chessie is a Tunnel Boring Machine (TBM) manufactured by Hennenknect in Germany. Some facts about Chessie:

• Chessie weighs 3,075 Tons (over 6 MILLION pounds)

• Overall length of the TBM is 308 feet

• The cutterhead size is 43.5 feet in diameter and has 559 cutting tools used to remove the soil from the tunnel face

• It rotates at a maximum speed of 2.3 RPM

• It removes sand and both soft as well as stiff layers of clay

• Power requirement for the TBM is 10 Megawatts, which is the equivalent of the energy needed to power 2,500 homes

• It crawls at an advanced rate of 2.4 inches per minute and can excavate approximate 50-60 feet per day

• There are over 9,000 total tunnel segments built - each segment weighs 10 tons with 5 yards of 18-inch concrete per segment. The segments were manufactured above ground in Chesapeake, VA and then transported by truck to the job site and then moved into the tunnel by mining cars.

• Each segment is comprised of precise, prefabricated segments of 10 segments for each ring.

• Chessie removed over 500,000 cubic yards of soil, which was disposed of in a DEQ-approved landfill

• Chessie 20-25 person crew works around the clock in two 10 hour shifts - the remaining part of the day is reserved for maintenance.

• All the data and control systems that operate Chessie are in the control cabin - The control cabin operator can adjust advance rate, drive direction, cutting wheel speed and screw conveyer speed.

• Construction was delayed in May of 2023 for nine months when the TBM hit an obstacle which turned out to be a large anchor from a turn of the 20th century English sailing ship.

Current Status of the Project - The tunnel was completely excavated end to end in January of 2025. Work is now underway to install the mechanical systems, bracing, electrical, tile and road with an anticipated traffic opening for early in 2028.

There is a short (5 minute) video available on the tunnel project webpage that outlines the project and shows how Chessie works here: The Thimble Shoal Channel Tunnel on Vimeo

For more information, please refer to Tunnel Project – CBBT.

Thanks for getting your geek on with me! :)