How to move a 30 million-pound, half-mile-long bridge

(CNN) -- Here's a record-setting job that qualifies as a "heavy lift."

On Thursday, workers in Indiana and Kentucky finished sliding a new nearly half-mile-long, 30 million-pound bridge from one set of piers to another, making it the "longest bridge in North America -- and perhaps the world" -- to slide laterally into place, according to the Indiana Department of Transportation.

The Milton-Madison Bridge spans the Ohio River, linking U.S. 421 between Madison, Indiana, and Milton, Kentucky. Starting Wednesday, workers moved it 55 feet from temporary piers to permanent refurbished piers. High winds across the river forced a delay in the job, until it could be completed the next day.

Here's how they did it: Workers placed polished steel sliding plates on top of the refurbished piers. Then, they pulled the bridge from the temporary piers to the refurbished piers with steel cables and eight computer-controlled hydraulic jacks.

Bridge geeks call this a steel truss bridge.

It measures 2,428 feet long and 40 feet wide. For drivers, it has two 12-foot-wide lanes and shoulders measuring 8 feet. For folks who prefer to walk, officials plan to add a 5-foot-wide sidewalk to the bridge during the coming months.

After inspections and and the completion of road connections, the bridge is expected to reopen to traffic in about a week.

Deterioration of the 85-year-old original bridge prompted the estimated $131 million project.

The old Milton-Madison Bridge was only one of more than a half-million aging bridges nationwide. A report released last year by Transportation for America labeled the bridge "structurally deficient." Drivers and passengers expect this critical infrastructure to be safe and reliable every day.

How safe is that bridge you're driving over?

The average age of all 607,380 bridges in the United States is 42 years, according to the American Society of Civil Engineers. About 25% of them are classified as deficient, according to a 2013 report by the Federal Highway Administration. To make all necessary repairs to America's bridges, the federal government estimates that it will cost $76 billion, according to the engineer group.


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