The Port of Miami Tunnel was built with a 42-foot-wide (12.86-meter-wide) tunnel boring machine (TBM) to relieve Miami's city center of 16,000 vehicles heading for the port daily. (Photo courtesy Herrenknecht Tunnelling Systems)

The Port of Miami, with its more than four million passengers a year, is not only the largest cruise ship port in the world but also an important freight terminal, processing around seven million tonnes of goods annually. (Photo courtesy Herrenknecht Tunnelling Systems)

Herrenknecht’s solution for Miami safely controlled both the soft-but-stable grounds at the tunnel entrance and exit, and the porous limestone subject to water pressures of up to three bar beneath the middle of the fairway. (Photo courtesy Herrenknecht Tunnelling Systems)

The excavated material, a mixture of water and soil and rock, was is conveyed via a slurry circuit using a screw conveyor with connected stone crusher and slurryfier box. (Photo courtesy Herrenknecht Tunnelling Systems)

Tunnelling work in Miami consisted of both eastbound and westbound tunnels. Work started in November 2011 and wrapped up in May 2013. (Photo courtesy Herrenknecht Tunnelling Systems)

In-depth investigations of the ground conditions in Miami showed that extremely porous material (Key Largo Limestone), also subject to high water pressure, had to be expected along about a third of the tunnel route. (Photo courtesy Herrenknecht Tunnelling Systems)

Herrenknecht’s tunnel boring machine (TBM) bored through as much as 61 feet (18.7 meters) a day and 329 feet (100.3 meters) a week. (Photo courtesy Herrenknecht Tunnelling Systems)