Juan Angel Martinez Diaz

As project director on London’s $1.2-billion Silvertown highway tunnel, Juan Angel Martinez Diaz successfully adopted hovercraft-like skates to rotate the job’s 39-ft-dia tunneling shield to drive both bores of the 0.9-mile crossing, saving critical time on the project’s tight schedule.

After completing the southbound drive across the River Thames, the 1,600-ton shield was rotated in a pit on the south bank and launched with its train into the northbound drive. The whole operation lasted six weeks less than the 120 days allowed, says Martinez Diaz.

He leads the Riverlinx Construction Joint Venture designing and building the tunnel for Riverlinx Ltd. The company has a design, build, finance and operate contract for the crossing with Transport for London (TfL).

Rotating the TBM “was pretty impressive implementation,” says Helen Wright, TfL’s program head. “They saved time … on something that was really complicated, really novel.”

By adopting techniques new to the U.K., Martinez Diaz’s “passion for innovation, for engineering … is what shines through,” says John Hagan, Riverlinx Ltd.’s CEO. “If it wasn’t him in that role, the project would not be finishing on time,” he adds.

Employed by Belgium-based, Spanish-controlled Ferrovial SE, Martinez Diaz has led construction since March 2022, around three years after the contract had been signed. Having by that point ruled out earlier notions of lifting the shield with a crane, “we didn’t know how to rotate the TBM,” he says.

He decided to adapt the hover-skate technique used by the project’s TBM supplier, Herrenknecht AG, a few years earlier on Germany’s Lider tunnel. The skates sit on cushions of inert nitrogen to eliminate fire risk.

Juan Angel Martinez Diaz

Juan Angel Martinez Diaz
Photo by Peter Reina

But while the German tunnelers slid their shield around a hairpin bend, the Silvertown team swiveled theirs, almost on its own footprint, in a pit and launched it back across the river.

Martinez Diaz’s team had three-and-a-half high-pressure months to perfect the plan and complete the pit. It took less than a day to turn the shield on the skates after it had reached the pit in February 2023.

While Wright believes Martinez Diaz is “really great at creating a vision.” He is also a very hands-on manager, adds Hagan. “He can spread himself too thin … [but] I know that if I bring a problem to him … he’ll resolve it personally.”

Martinez Diaz concedes that he likes “to control everything,” but stresses, “I cannot do anything without my team.” Among the 300 or so people on the project, a handful has been with him since his earlier London projects, he says.

Before the U.K., he had worked mainly in Spain and in Chile. And since 2012, he has tunneled about 19 miles under London for the city’s Crossrail, Northern Line extension and Tideway mega sewer projects before taking on Silvertown.

Now, with “everything trending very well,” he expects the tunnel to open on time in March 2025. Having settled in London with his wife and two teenage sons, and gained British citizenship, “I would like to stay,” he says.

All ENR 2023 Top 25 Newsmakers will be honored at the Award of Excellence Gala on April 11 in New York City.