Baltimore bridge salvage: 'This is a game of Jenga you don't want to lose'

US Army Colonel Estee Pinchasin looks out at the thousands of tonnes of twisted, broken steel and concrete jutting out from the dark waters of Maryland's Patapsco river, and delivers her assessment: an "unforgiving mangled mess".

"That's the best way to describe this," the fatigue-clad veteran says from the deck of an Army-operated salvage vessel, the Reynolds. "It's hard to explain steel that is cantilevered, bent and smashed with so much force."

The "mess" Col Pinchasin has been tasked with clearing is the tattered remnants of Baltimore's Francis Scott Key Bridge, strewn around - and embedded into - the Dali, a massive 948ft (289m) cargo ship that now sits motionless under an expanse of shredded metal, with partially crushed shipping containers hanging from its sides.

The mangled mess is self-explanatory. But why unforgiving? Because, put simply, anything and everything here is a potential threat to the lives of salvage crews.

The Dali's collision with the bridge in the early hours of 26 March brought the structure down in a matter of seconds, leaving six workers dead and the ship stuck. This has prompted a huge response that has included the US Army Corps of Engineers, Navy, Coast Guard, Maryland authorities and specialist private firms.

The effort aims to unblock the 700ft (213m) wide and 50ft (15m) deep shipping channel, re-float and remove the Dali and clear whatever remains of the estimated 3,000 to 4,000 tonnes of debris from the wider Patapsco.

"Those things are happening simultaneously," Col Pinchasin, the Army Corps of Engineers Baltimore district commander, told the BBC. "But the priority is for the channel, because we need to get those people back to work and help all the businesses that are affected."

The port is one of the busiest on the East Coast of the United States and a key regional hub for goods including steel, aluminium and agricultural equipment. It is used by car-makers including General Motors and Honda. As many as 15,000 jobs depend on it, including 8,000 directly employed there.

The mission has turned the area into a hub of activity, buzzing with small US Navy sonar vessels and police boats, workers testing spark-emitting hydraulic shears, and - so far - seven huge crane barges, including the Chesapeake, a 1,000-tonne capacity crane once used by the CIA to build a ship used to recover a Soviet submarine from the bottom of the Pacific.

Piece by piece, debris will eventually be disassembled and lifted onto barges to be taken away.

"With every layer of debris they remove, they have to go back in and survey the wreckage to see if it reacted the way we thought it was going to," Col Pinchasin said. "Are there any instabilities? Are they things we missed? What did we not see":[]}