An engineer experienced with investigating structure collapses, including the 1982 Cline Avenue bridge disaster that claimed 14 lives, said the first meeting regarding the Horseshoe Casino walkway collapse will be crucial. (Graphic)

"The first meeting after the collapse of all the principals involved would be most important, because you sit down and review the walkway design and shop drawings," said Adrian Ciolko, a senior engineer for CTL Group in Skokie, Ill.

CTL, which has offices in Illinois and Washington, D.C., is a firm with experience investigating structure failures, including the collapse of the World Trade Center's twin towers, the Cline Avenue collapse in East Chicago and the 2007 collapse of an interstate bridge in Minneapolis that left 13 people dead.

Ciolko said typically his firm would collect information and send out structural engineers who would gather observations and take samples. Experts in the labs would study them and compare for compliance with national standards for manufacturing materials.

Engineers then would make a calculation of what the walkway was capable of supporting. After the information was analyzed, the firm would draw hypotheses and conclusions about primary cause of failure.

Ciolko said the casino walkway was a special structure with unique requirements that differ greatly from a typical bridge.

"We'd retrieve samples of the bracing and look at the actual walkway structure itself and inspect them carefully, looking for signs of undue deformation," Ciolko said.

"They would show how the structure was absorbing loads and how it was stretching or pushing together so we could establish the sequence of events that led the walkway to fall."

Among the most distinctive tell-tale signs are metal bending or cracking or when one piece of metal slides across another. There are tests that can evaluate whether building materials were the suitable strength for the application, he said.

"If you have something that's land-based adjacent to something that's water-based and one is more movable than the other, you have to be careful how the bracing is designed," he said. "It has to be able to accommodate the weight of the bridge or walkway and the movement as the two things are brought together. It may be that it wasn't designed correctly or something may have shifted in a way that wasn't anticipated.

"Hopefully, there will be lessons learned from this incident so they can re-erect the walkway and be able to take measures from it happening again," he said.