The $1-billion Port of Miami tunnel project, one of the nation's more notable infrastructure contracts, experienced a literal "breakthrough" moment July 31, as crews leading the 380 ft-long tunnel boring machine completed the first of two "tunnel tubes" under Biscayne Bay.

In a press statement marking the occasion, Miami-Dade County Mayor Carlos A. Gimenez said: "It is a milestone day for PortMiami. The tunnel is critical to PortMiami's future growth because it will allow port traffic to move more expeditiously to and from the interstate system, and will help reduce traffic downtown. This project has been an engineering feat of note. But, even more significantly, the PortMiami tunnel is an example of what our port is all about—a public-private collaboration that will make our port even more dynamic tomorrow than it is today."

As ENR Southeast reported previously, the project is the result of a $1-billion design-build-finance-operate-maintain contract between the Florida Dept. of Transportation and Miami Access Tunnel, a partnership between Bouygues Travaux Publics of France and Meridiam Infrastructure, Luxembourg.

This cool Youtube video posted by Earthcam will give readers an even greater appreciation for this most recent engineering accomplishment.

Twin, 4,200-ft-long, 43-ft-dia tunnels will connect the port on Dodge Island with nearby Interstate 395. The tunnel boring crews broke through onto Dodge Island, from their starting position on nearby Watson Island. They'll now disassemble and then re-assemble the TBM—nicknamed Harriet—and head back to Watson Island.

The tunnel is estimated to be the largest soft-ground tunnel in the U.S., running approximately 120 ft under the channel at its deepest point. The $45-million TBM was custom engineered and fabricated by Herrenknecht in Germany.

Finally, here's a photo from the "breakthrough" celebration showing construction crews cheering—a pretty nice sight to see these days. Here's hoping they'll have more to celebrate soon.

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TBM crews celebrate their "breakout" moment. (Photo Courtesy of Bouygues Civil Works Florida)