MIAMI -

Piece by piece, workers assembled Thursday a giant drill that will be used to dig the new Port of Miami tunnel, which will give trucks carrying cargo easier access to ships arriving at the port.

The assembly is a high-stakes high-wire act, with half a billion pounds and millions of dollars' worth of sharp steel dangling from a few wires.

As drivers sped by and engineers stood sweating the details, the cutter head was slowly dropped down, inch by inch, to the area where it will begin digging up the tunnel.

"That's the mechanism that will be like a razor cutting into the limestone," said Christopher Hodgkins, of Miami Access Tunnel.

The cutter head is the business end of the tunnel boring machine that is a football field long. It's four stories high and 43 feet wide.

Over the next eight months, the machine will push through underground to the Port of Miami. Then, it will spend another six months boring back.

The pieces of the $45 million puzzle began arriving more than two months ago from Germany. When fully assembled, it will be the largest tunnel boring machine in the U.S.

"It's the first of its kind. This machine was built just for this job," Hodgkins said.

The project has already created 1,000 new jobs, two-thirds of which were filled by South Floridians.

"We've got a challenge ahead," Hodgkins said. "We've got some phenomenal engineers and we've got a great design."