Heavy metal ballet

[TexasTowelie]

The spans of the Margaret McDermott Bridge take shape behind a field of wildflowers. (Tom Fox/Staff Photographer)

To assemble Dallas’ newest Calatrava-designed arches, two cranes perform a precise pas de deux with up to 100 tons of steel

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.

Read more: http://interactives.dallasnews.com/2015/calatrava-arches/