MIAMI (CBS4) – Almost everyday, new stretches of bridge appear beneath it.
You have seen it hovering in all its yellow hugeness over the improvement project on the interchange of the Palmetto and Dolphin Expressways in Miami-Dade County.
It is 400 feet long, weighs 400 tons and resembles a piece someone swiped from the Green Giant’s erector set. Technically, it is called a self-launching, self-propelled gantry crane.
Those who use it call it “The Smooth Operator,” and it’s earning its name.
The Smooth Operator is an engineering marvel that is constructing the four main flyovers of the new interchange, not from the ground up but from the sky down, saving time and traffic hassles in the process.
Bridge segments that are 46 feet wide and weigh 80 tons are hauled to the construction site on flat bed trucks where the crane, mounted on moving railings above the interchange, lifts them up, propels them forward, and gently lowers them in place at the rate of two segments or so a day.
The gantry crane, that travels on and above the bridge as it builds it, eliminates the need for conventional ground-based cranes that block lanes, cause traffic snarls and slow construction time by having to be put in place before each work cycle and removed after.
“The contractor that won this project was able to use this crane and other techniques to cut the build time on this interchange to five years, instead of eight years,” said Oscar Gonzalez, a spokesman for the Florida Department of Transportation.
The Smooth Operator is driven by a controller holding a small console, worn around the neck, with several joysticks on it. The gadget resembles the box a child would use to operate a remote controlled toy.
Ricardo Ayala, an operator-in-training, marveled at the massive piece of machinery and the opportunity he’s been given to work with it, under close supervision.
“It’s a lot of responsibility,” Ayala said of personally steering 400 tons of complex gear. “It’s amazing. It’s an amazing machine. I love it.”
American ingenuity can’t take credit for the time and headache-saving device.
The crane was designed and built in Italy. For all their quaintness, the Europeans were decades ahead of the United States in development of the “segment” system of bridge construction.
The machine was shipped to Miami-Dade in 40 containers and assembled on location. The Smooth Operator was designed specifically for the Palmetto/Dolphin interchange project and will lay nearly 800 segments of overpasses – almost two miles worth.
Smaller bridges for on and off ramps will be built in the more time-consuming conventional fashion that involves building wooden forms on the site, filling them with cement and waiting for it to dry.
When the interchange – that the FDOT calls the most ambitious road construction in South Florida history – is completed, most will enjoy a seamless, state of the art transition to and from the Palmetto and Dolphin expressways from all directions.
The $560 million job is expected to be finished in about three years. It probably would not have begun yet, but for an infusion of some $87 million in federal stimulus funds.