INTECSA DELIVERS DEEP VALUE ON CHESAPEAKE BAY’S $755M TUNNEL EXPANSION

How a Spanish firm reshaped the trajectory of Virginia’s $755 million infrastructure project

CHESAPEAKE BAY BRIDGE AND TUNNEL VIRGINIA

Intecsa, a Spanish engineering firm, played a key technical role—led by its senior experts Stefano Murgia (Head of Tunnels and Geotechnics) and Pablo Fraile (Head of Structural Engineering)—in the Design & Build contract for the construction of a tunnel parallel to the existing Thimble Shoal Tunnel. The estimated $755 million project was tendered by the Chesapeake Bay Bridge and Tunnel District and is one of the most ambitious marines tunneling efforts currently underway in the United States.

“We weren’t there just to support—we were there to shape,” says Pablo Fraile. “From design concept to temporary works, our team brought solutions that changed the trajectory of the project.”

The project, led by a joint venture of Dragados USA and Schiavone Construction, involves building a new tunnel approximately 250 meters west of the existing Thimble Shoal Tunnel, beneath the main navigation channel connecting the Chesapeake Bay to the Atlantic Ocean. The new tunnel, called the Parallel Thimble Shoal Tunnel, is designed to increase traffic capacity and enhance the resilience of the existing crossing.

Intecsa under the leadership of senior experts Stefano Murgia, and Pablo Fraile, was brought on as a specialized technical consultant, supporting the joint venture from bid to execution with design validation, value engineering, and the development of temporary works. The team became involved during the early bidding phase, at a time when the project was originally specified as an immersed tunnel—a method that posed considerable logistical and environmental challenges.

At that stage, Intecsa proposed an alternative: a conceptual tunnel boring machine (TBM) solution. Backed by solid technical justification, the approach was not only accepted but eventually incorporated into the final design requirements published by the client.

“It wasn’t a minor tweak—it was a strategic shift,” explains Stefano Murgia. “We showed that the TBM method could reduce risk, simplify marine work, and improve constructability.”

In collaboration with the joint venture and design teams, Intecsa also contributed to design optimization, engineering of temporary structures, and comprehensive risk analysis. These contributions helped reduce structural costs, improve constructability, and mitigate execution risks—delivering measurable benefits throughout the project’s critical stages.

Intecsa’s scope included:

As part of its engineering responsibilities, Intecsa carried out advanced modeling and structural analysis to support both design validation and construction strategies. This included 3D FLAC simulations to model tunnel face pressure and ground behavior under variable geotechnical conditions, as well as SAP2000 analysis to assess the performance of tunnel segment rings under combined axial and bending loads. The firm also designed several temporary structures, including jacking frames, sacrificial rings, gantry crane supports, and trestle docks—each adapted to the marine environment’s spatial and logistical demands.

Designing these temporary works proved particularly challenging, given the extremely limited space available on the man-made islands. The engineering team had to develop compact yet fully functional solutions, carefully navigating the risks of interfering with existing infrastructure and ensuring safe execution in constrained conditions.

In parallel, Intecsa led key value engineering efforts that delivered measurable construction benefits. Among the most notable were a 55% reduction in jet-grout plug thickness, a 35% reduction in slurry wall lengths, and an over 450% decrease in steel reinforcement in specific segments. These optimizations not only cut material usage and environmental impact, but also accelerated critical construction phases, resulting in a more efficient and cost-effective tunnel delivery.

“This wasn’t about saving money for the sake of it—it was about engineering smarter,” says Pablo Fraile. “Every adjustment we proposed was grounded in rigorous modeling and verified on-site.”

In addition, Intecsa provided on-the-ground support during construction, assigning engineers to coordinate procurement, resolve site-specific technical challenges, and oversee real-time implementation of design adjustments.

A Strategic Footprint in the U.S.

Founded in 1965, Intecsa has delivered complex infrastructure projects across Europe, Latin America, the Middle East, and North America. The Chesapeake Bay tunnel marks a milestone in the firm's U.S. portfolio, which also includes geotechnical and design work on the Alaskan Way Tunnel in Seattle, Northgate Link, and the Hampton Roads Bridge-Tunnel Expansion in Virginia.

“Our work in the U.S. demonstrates that technical depth and international experience are not mutually exclusive,” says Stefano Murgia, Head of Tunnels and Geotechnics. “We bring global standards, and we adapt them to the local context.”