Heavy metal ballet

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Heavy metal ballet
The spans of the Margaret McDermott Bridge take shape behind a field of wildflowers.
Heavy metal ballet
The spans of the Margaret McDermott Bridge take shape behind a field of wildflowers.

In construction, it’s called a two-crane pick. Don’t let the simple name fool you. The complex maneuver requires precise execution to minimize risk and maximize safety.

As performed by workers assembling the new Santiago Calatrava arches near downtown Dallas, it’s an intricate industrial ballet, a slow-motion dance of steel using wire rope slings, shackles, spreader beams and lifting lugs, either welded on or bolted on.

Working in unison, two cranes lift and swing long arch segments into place. Some pieces weigh 100,000 pounds and more. Determining the exact center of gravity is critical.

“It’s not a job for everybody,” said Jeff Keller, a crane operator on the project.

“You have to keep your cool.”

In 1999, the late architecture critic David Dillon wrote that the Calatrava bridges then proposed for Dallas “would add poetry and drama to a river that has never sung.”

As much art as engineering, the Margaret Hunt Hill Bridge opened 13 years later. Its 40-story arch and curving cables grace one end of Woodall Rodgers Freeway.

Now, more poetry is emerging from both sides of the Trinity River, this time alongside Interstate 30 in view of hundreds of thousands of motorists every day. []

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