Critical Day In $1B Port Of Miami Tunnel Project

MIAMI (CBS4) – Construction of the new $1 billion Port of Miami tunnel took a giant leap forward Thursday afternoon when a critical piece of the giant Tunnel Boring Machine was raised into the air and then lowered into the ground.

The so-called "cutter head" is the most vital part of the tunnel boring machine and will carve the twin tunnels connecting Watson and Dodge Islands.

The 43-foot wide, four-story high mechanism was raised into the air by a special 800-ton crane and then lowered into the launching pit in its place as the head of the huge tunneling machine. The huge, rotating steel plate will bore through the limestone beneath Biscayne Bay.

Click here for a slideshow of the massive machine coming together.

The entire $45 million boring machine, nicknamed Harriet, is longer than a football field and about as tall as a four-story building.

Christopher Hodgkins, VP of Miami Access Tunnel explained the machine's importance.

"It is designed for this port tunnel. It is designed to make sure to deal with geological formation that we have which is hard lime stone. It is composed of what looks like swiss cheese. It has holes in it," said Hodgkins.

‪Hodgkins said the tunnel represents a new way to grow and go for the Port of Miami.

"About 5 thousand trucks a day go through downtown Miami. They clog the street. For cargo which is the most important thing for us here and the cruise lines, the idea is to get that traffic and funnel it to the port to help us grow."

Crews have been assembling the machine in a giant concrete pit in the middle of Watson Island ever since it arrived in parts back in June on a ship from Germany. The machine weighs more than 2,500 tons.

When the Tunnel Boring Machine is fully assembled in the launching pit, a dedication ceremony will take place and drilling under Government Cut to the Port of Miami will begin. Drilling is expected to begin in October.

The boring machine will dig about four feet an hour which should take it about 6 months to re-emerge at the port on Dodge Island. It will then be partly disassembled, turned around and re-assembled before boring out the separate return tunnel to Watson Island.

The tunnel will consist of two tubes featuring two lanes each.

The project is supposed to ease traffic congestion from cargo trucks heading to the Port of Miami.

Construction is expected to be complete by May of 2014.

When the twin-tube tunnel is completed, the Tunnel Boring Machine will be dismantled and removed from the site.

(©2011 CBS Local Media, a division of CBS Radio Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed. CBS4 news partner The Miami Herald contributed material for this report).