The crane barge crash that shut the Sunshine Bridge for months has triggered one of the U.S. Coast Guard's more-serious levels of maritime investigation, possibly leading to public hearings that could include testimony from those who saw or heard a crane clang into the span Oct. 12.

The Coast Guard said Thursday it needed a formal investigation to determine why those operating Marquette Transportation Co.’s Kristin Alexis hit the Sunshine Bridge in the middle of the night.

"The (investigation) team will also identify any recommended actions to prevent similar incidents from occurring in the future," the Coast Guard said in a statement Thursday. 

A formal investigation is among the Coast Guard’s highest levels of inquiry. According to the agency’s investigative manual, such a probe would very likely have public hearings with witnesses and parties of interest would be identified.

The Coast Guard and Marquette have not said who was piloting the Kristin Alexis on Oct. 12 and whether the pilot was properly qualified or licensed. In announcing its investigation, the Coast Guard said it would “examine all aspects" of the crash to uncover "any unsafe conditions, which may have contributed to the casualty."

Louisiana Transportation Secretary of Shawn Wilson said Thursday he met last week with Marquette’s senior leadership, including CEO John Eckstein. The Paducah, Kentucky-based towboat operator, which employs more than 400 people in Louisiana, was pushing the crane barge when it hit the bridge.

The state has said it could cost up to $5 million to repair the span, which will be closed until January at the earliest. Marquette has filed paperwork in federal court seeking to limit its financial exposure to $1.55 million, the value of the Kristin Alexis.

While the two sides must settle their financial differences, Wilson said the parties agreed that restoring the bridge to a safe condition is the most important goal. He said both sides pledged to work together and avoid “undue legal posturing” that could disrupt that work.

“We are committed and focused on completing the needed repairs,” the head of the Louisiana Department of Transportation and Development said in a statement.

Marquette president Damon Judd said, in a statement released by Louisiana highway officials, that its engineers and experts were directed to work with DOTD.

Late last month, Gov. John Bel Edwards called the crash “an act of negligence.”

In a statement separate than the one released by state officials,  Marquette pledged also to cooperate with the Coast Guard investigation and acknowledged the headaches it has caused.

Judd called the crash a "very unfortunate incident" that came despite the company's overall safety record, having delivered billions of tons of product and cargo on Louisiana waterways for more than four decades.

"We recognize that the closure of the Sunshine Bridge has created a significant disruption for Louisiana citizens that travel the La. 70 route daily," Judd said in the statement. "We apologize for the inconvenience this situation has created for these residents and motorists."

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The repairs have caused extensive daily detours for families, business, farmers and industries that had relied on the bridge in St. James Parish and near Donaldsonville.

DOTD has hired Coastal Bridge Co. to oversee jacking apart and realigning the damaged section of bridge, so a new metal beam can be installed.

The Cooper Consolidated crane barge hit the load-bearing beam on the bridge's southwestern side, wrecking the huge piece of steel. At the time, the Kristin Alexis was pushing the barge crane upriver in the dark and was trying to go under the bridge’s western span, which, though navigable, is lower than the section of the arching bridge that crosses over the main river channel.  

A fixed pedestal on the unmanned barge is believed to have hit the bridge, the Coast Guard said. The crane’s boom was down, Coast Guard and company officials have said. Stuck for nearly four hours under the bridge, the barge had to be lowered before it could be moved, according to Port of South Louisiana and Louisiana State Police reports.

Before Thursday’s announcement from the Coast Guard, the agency had been conducting a preliminary investigation and gathering evidence of what is called a "marine casualty.” 

Under Coast Guard rules, the agency requires the recording and reporting of maritime incidents with varying levels of seriousness, from small diesel spills and lost propellers to major crashes and deaths. Part of the goal of a preliminary investigation is to determine what type of incident happened and the level of investigative effort necessary. 

Petty Officer 3rd Class Travis Magee, a Coast Guard spokesman in New Orleans, said the Sunshine Bridge investigation is a "unit designated formal investigation,” which means the probe has been deemed formal by a top marine inspection officer.

The most intensive form of formal investigation is known as a Marine Board, which must be called for by the Coast Guard's commandant. Marine Boards are typically reserved for major national incidents or those with a high loss of life.

Capt. Tom Kaminski, chief of prevention for the Coast Guard's 8th District, said in a recent interview that the agency's more intensive investigations of marine casualties look for the root cause and "lessons learned" that can feed into the agency's regulatory process.

The Coast Guard has not provided other details about the crash, including why the towboat chose the western channel, who was the captain was or how the height of the bridge span, the crane barge or both were misjudged.

DOTD also said that some jacking equipment to begin realigning the damaged bridge has arrived and fabrication of a replacement beam is expected to be finished about the middle of next week.

The Coast Guard set up an email account for interested parties to make comments or send information important to the investigation. The address is Accidentinfo@uscg.mil.

Follow David J. Mitchell on Twitter, @NewsieDave.