Port of Miami Tunnel connects people, business

Herrenknecht built this tunnel boring machine (TBM) to chew through coral, soft and porous rock under Biscayne Bay to create the Port of Miami Tunnel.

High-tech boring machine, expertise made it possible

May 10, 2023

Editor’s note: In 2023, the Newsroom will explore the importance of tunnels in North America and around the world. Tunnels are an example of creative and engineering genius, and more importantly, they provide practical solutions and help move people and goods from one point to another. Enbridge has committed to building the Great Lakes Tunnel to house the Line 5 pipeline and possibly fiber cables to improve high-speed internet and 911 emergency services for northern Michigan.

In 2022, Miami Today called the Port of Miami Tunnel the “gold standard for tunnels in Florida and in the United States both during construction and now during operations and maintenance.”

Why such high praise?

Miami Today gave the tunnel that label because of the vital connections the tunnel makes possible as well as its high-tech construction techniques.

The tunnel, 120 feet below sea level with a 42-foot-diameter girth, connects “…the mainland to Miami-Dade County’s second-greatest economic engine, supporting more than 334,000 jobs and contributing $42 billion annually,” according to Miami Today. “Now, as local governments are looking at adding other tunnels to increase mobility, the port tunnel’s track record offers guidance for what more tunnels might achieve.”

As Enbridge prepares to build the Great Lakes Tunnel project under the Straits of Mackinac to house its Line 5 light oil and NGL pipeline, the company will leverage the latest technology and employ experts who make such engineering marvels possible.

One of the leading tunnel boring machine (TBM) manufacturers in the world is Germany-based Herrenknecht, which created the giant TBM for the successful Port of Miami Tunnel project, as well as one for the new, 13-mile-long Chesapeake Bay Tunnel under construction in Virginia.

“Every project we undertake is unique,” said Steffen Dubé, president of Herrenknecht Tunnelling Systems USA.

“It requires us to build special TBMs designed to meet the specifications of the job and the geology. We consider all of that in the critical planning stages.”

Overcoming challenges

In Miami, the TBM had to go under Biscayne Bay, tunneling through coral, soft and porous rock. The team had to inject a specially developed grout into the porous material to stabilize it during boring. Additionally, the size of the tunnel was large, more than 40 feet in diameter. The TBM had to excavate two undersea tunnels to form a four-lane road.

 

“The technology is proven and safer than any other means of construction.”

—Steffen Dubé, president of Herrenknecht Tunnelling Systems USA

Dubé also explains the tunnels are built to withstand water pressure, which is measured in bars. Herrenknecht says TBMs can be built to withstand high-water pressures of more than 15 bar of pressure at depths of more than 500 feet below the surface.

“The technology is proven and safer than any other means of construction,” said Dubé.

“We built the TBM to drill dual tunnels under the water off of Miami. The Tunnel now carries cars and trucks, easing congestion and making connections possible in that busy seaport. It’s a proven success.”

Comparison to the Great Lakes Tunnel Project

The Great Lakes Tunnel Project would need a TBM about half the size of the Port of Miami one. The Michigan tunnel would run approximately four miles under the Straits of Mackinac, at a depth of at more than 220 feet below the lakebed in some places.

The tunnel will provide a utility corridor; Line 5 would occupy a portion of the tunnel, with a 30-inch diameter pipeline attached to one wall and utilities, such as high-speed fiber cables, connected to another section of the tunnel.

“We believe the Great Lakes Tunnel project makes a great deal of practical sense,” said Mike Moeller, Enbridge’s director of operations for the Great Lakes Region.

“The tunnel would remove the pipeline from the water and place it into a secure tunnel below the lakebed and away from any possible anchor strikes. This would reduce the chance of an anchor strike to zero while protecting the precious waters of the Great Lakes. Equally important, a tunnel would keep energy flowing to the region, which depends on it every day to heat homes and businesses, as well as help in the production of more than 6,000 products—cell phones, eyeglasses, and medicines, to mention just a few items.”

Enbridge, which will build and pay for the tunnel’s construction, will rely on the expertise of engineers not only in the U.S., but also around the world, such as Herrenknecht.

Proven technology benefitting society, environment

Herrenknecht has been building tunnel boring machines for projects around the world for more than 45 years. The company’s long-standing legacy includes successful projects from London to Istanbul and Miami and literally from all over the world. It has delivered TBMs for tunnels below busy metropolises, through mountains, and under the sea – all with one purpose.

“Our team is focused on safe, purposeful solutions that benefit people,” continued Dubé.

“Tunnels help move people via roadways and rail. They also provide access, making connections and encouraging commerce that we all rely on in our daily lives.”

The Port of Miami Tunnel is just one example of tunnels making a difference and setting a standard for others to follow.

Perhaps, the Great Lakes Tunnel Project will be the next success story in the U.S. Enbridge is awaiting permits to begin construction.