GONZALES — A crane barge crash into the Sunshine Bridge last fall should have caused the Mississippi River bridge to collapse, a top state highway official told a federal panel investigating the crash Thursday.

David Miller, chief maintenance engineer for state Department of Transportation and Development, said that when a computer model was run, the amount of damage the barge caused to a key support beam for the bridge near Donaldsonville should have caused what Miller called a complete failure.

"On paper, that probably should have failed," Miller told the joint panel of U.S. Coast Guard and National Transportation Safety Board investigators who have been meeting in Gonzales this week. The hearings are scheduled to continue through Saturday. "If you ran the numbers, on paper, it probably should have come down."

The Kristin Alexis, a Marquette Transportation towboat working under charter with Cooper Consolidated, ran the Cooper barge crane into the lower, western span of the bridge shortly before 1:50 a.m. Oct. 12, shutting the bridge down and disrupting cross-river highway traffic for months.

The tugboat's master captain underestimated the crane's height by about 6 feet before handing off control of the tug to the vessel's pilot, his second in command, some time after midnight. 

Miller's revelation about the theoretical risk to the Sunshine Bridge came Thursday as he discussed DOTD's response to the crash and its effort to make emergency repairs. The bridge was closed entirely from Oct. 12 to Dec. 1, then partially closed for crash-related repairs through the middle of March. 

Miller said the crash occurred at the worst possible location: a critical steel beam that bears the compression stress of 1.7 million pounds of force, or essentially the weight of 142 elephants.

Once the beam was bent inward, Miller said, the beam and the bridge lost a lot of their strength. He compared the impact of that damage on the bridge's overall ability to handle weight with what happens to an aluminum soft drink can once its side is bent.

While a metal can is difficult to smash when unbent, once the can has a small bend or small crinkle in the metal, the can is easily crunched, he said.

DOTD contractors had to install special jacks to hold the weight of the bridge at the damaged beam, then cut it out, reheat the remaining section to bend it back in place and then install a new section of beam. 

According to Miller's testimony and information he provided to the panel, the emergency construction repairs and related engineering and inspection have cost $6.47 million so far. Another $200,000 or so in invoices are pending final review. Around the time of the crash, DOTD had estimated the cost to be up to $5 million.  

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Miller said the Sunshine Bridge is seen by the agency as one of its "fracture critical" bridges because of the lack of overall redundancy in the bridge's support members and the risk that damage to any one of them can pose to the structure.  

But Miller said internal redundancies in the Sunshine Bridge, which can't be accounted for in computer modeling, allowed the pressures on the span to shift to other beams and continue to hold the bridge up, despite the apparent impact of the crash accounted for in department calculations.

The federal investigative panel has been exploring a Marquette pilot's decision to use the lower western span and why he didn't check on the bridge and crane's height. Under maritime rules, the ultimate responsibility for the safety of a vessel and its tow lies with the captain of the ship while a voyage is underway.

On Wednesday, Wendell Landry, Cooper's director of stevedores, told the panel he never thought any of Cooper's large cranes ever went under the lower alternative span of the bridge. Since the crash, the company has changed its polices to require that pilots take them only in the main channel under a bridge.

Since the crane barge that hit the bridge went into service on the river in May 2018, the crane, known as the Mr. Ervin, had made 12 other round trips under the bridge and all were through the higher, main channel, Landry has testified.

Cooper bought the Mr. Ervin crane and another, slightly smaller crane, known as the Hulk, in late 2017 from a coal mining company and refurbished them for use on the river.

On Thursday, the panel also learned the pilots of the tug had another option to check their route, besides Marquette or Cooper. George Petras, training coordinator of the U.S. Coast Guard's Vessel Traffic Service in New Orleans, said the service routinely tells mariners about the air gap under bridges on the lower Mississippi.

The service works like an air traffic controller for ships, in particular in more congested or tricky parts of the river. Notes in a Vessel Traffic Service summary of the incident shown Thursday appear to indicate the Kristin Alexis hadn't called the service about the bridge ahead of time. 

Under questioning from a Cooper lawyer, who cited the river conditions at the time of the Oct. 12 crash, Petras agreed the alternative western channel should not have been used while the tug was pulling the Cooper crane.

"If we had those pieces of information, no," Petras told the lawyer.

Follow David J. Mitchell on Twitter, @NewsieDave.