Locale : North America (English)
1 / 2
Long shot of a boat aerial shot of the tunnel

Modernizing a landmark crossing of Chesapeake Bay

A tunnel boring machine will construct a new tunnel between two artificial islands.

Develop elegant and innovative solutions that enhance quality


Completed in 1964, the Chesapeake Bay Bridge-Tunnel crosses the mouth of Chesapeake Bay, an environmentally and economically significant watershed. The four-lane crossing consists of a series of low-level trestles interrupted by two tunnels, each about one mile (1.6 kilometers) long, beneath the Thimble Shoal Channel and Chesapeake Channel.

To provide an easier crossing for an increasing number of motorists, the Chesapeake Bay Bridge and Tunnel Commission decided to create a new bored tunnel between two artificial portal islands in Chesapeake Bay. Maintaining strict state and federal environmental standards was a priority.


As part of a design-build joint venture created by Dragados USA and the Schiavone Construction Company, Mott MacDonald was retained as the lead designer for the Parallel Thimble Shoal Tunnel, which will run alongside one of the two existing tunnels. We are responsible for obtaining necessary permits and documenting compliance with NEPA.

A tunnel boring machine (TBM) will be assembled inside a large pit and will excavate the tunnel from Island 1 to Island 2, a distance of about one mile. The TBM will install precast concrete tunnel segments as it proceeds, and will be disassembled and removed after it reaches Island 2. Because the environmental challenges of large-diameter tunneling are new to local authorities, Mott MacDonald has helped describe the technology in a clear and timely fashion.


Clear communication has helped keep the project on schedule. Mott MacDonald is exploring ways to reduce the impact of pile driving on seals and other marine mammals, and on endangered species such as sturgeon.

The new parallel tunnel will reduce the number and total hours of lane closures caused by accidents, disabled vehicles, or other interruptions. It will provide operational redundancy and improved levels of service, giving new life to a landmark of engineering.

icon-arrow-down-sml icon-arrow-left-lrg icon-arrow-left-sml icon-arrow-right-lrg icon-arrow-right-sml icon-arrow-up-sml icon-champions icon-close icon-download icon-education icon-email icon-grid-view icon-language icon-link-to icon-list-view icon-location icon-login-register icon-minus icon-more icon-phone icon-plus icon-recently-viewed icon-search icon hash key-facts-corner-sash quote-underline social-icon-facebook social-icon-googleplus social-icon-linkedin social-icon-twitter social-share-icon-facebook social-share-icon-facebook social-share-icon-googleplus social-share-icon-googleplus social-share-icon-instagram social-share-icon-instagram social-share-icon-linkedin social-share-icon-linkedin social-share-icon-twitter social-share-icon-twitter social-share-icon-youtube social-share-icon-youtube sina-weibo MM-Shape01-Quote-Views MM-Shape03-Quote-Locations MM-Shape05-Quote-Projects MM-Shape12-Quote-Sectors MM-Shape13-Quote-Expertise MM-Shape14-Quote-About-Us MM-Shape14-Quote-Careers checkmark icon-expand-view icon-apply-now menu sphere icon-cookies icon-legal icon-registered-companies target rotate-screen video-replay-flat video-replay audio-mute audio-play