Caution urged as engineers prepare controlled demolition of Key Bridge truss in operation to refloat Dali

BALTIMORE -- Engineers are rigging explosives to refloat the Dali, a cargo ship stuck in the Patapsco River since March when it crashed into the Francis Scott Key Bridge. 

Politely called "precision cutting," the controlled demolition will use small charges to split the portion of the collapsed bridge on the ship's bow into smaller, more manageable sections. 

"The operation requires careful handling of roadbed material, crushed containers, and bridge fragments currently resting on the vessel," officials said Monday.

Officials said it's similar to the method used to demolish the Harry Nice Memorial Bridge last year in Charles County. 

The U.S. Army Corps of Engineers, leading the salvage effort, said it is the "safest and swiftest" way to remove the thousands of tons of wreckage pinning the massive ship. 

Though it might be the safest method, residents in the vicinity of the explosion are asked to take precautions. 

Safety Zone established

Officials urge maintaining a safe distance from the operation and "highly discourage" spectating. A 2,000-foot Safety Zone has been established, where hearing protection is required.

Most of the Safety Zone consists of the Patapsco River, but portion of Hawkins Point falls in its range. Unified Command said "focused efforts" will be made to prepare those in the area for the event. 

That effort will include a mobile notification in collaboration with the Maryland Department of Emergency Management. 

An animation was released detailing how the demolition might look. The explosions will look like multiple puffs of smoke and sound like fireworks. 

Unified Command said the exact time of the cutting depends on environmental and operational factors, but officials hope to refloat the Dali by the end of the week.

Refloating essential to reopening channel 

The removal of the steel structure of the bridge, called "section four," is another big step toward refloating the Dali to clear the Fort McHenry Channel and provide access to the Port of Baltimore, which has been limited since the disaster. 

The Unified Command's priority is to reopen full access to the port, which it aims to do by the end of May. 

"We remain focused on restoring the Marine Transportation System while ensuring the protection of the public and the environment," Capt. David O'Connell, Federal On-Scene Coordinator for the Key Bridge response, said in a statement Wednesday. "By using precision cuts, we reduce risks to our personnel and can safely and efficiently continue clearing the channel for the Port of Baltimore."

Since the collapse, four temporary channels have opened to allow ships, including some commercial vessels.

The fourth and largest channel closed after five days as salvage operations continued, but an even deeper channel is expected to open as soon as the Dali is unstuck and removed from the channel.   

The main 50-foot-deep channel is still set to reopen by the end of May. A giant hydraulic claw will make that possible by removing pieces of the bridge embedded in the Patapsco River bed. 

Six victims now accounted for 

Around 1:30 a.m. on March 26, the malfunctioning Dali collided with the Key Bridge, causing it to collapse, and knocking eight men, who were repairing potholes on the bridge, into the Patapsco River.

On Tuesday, the body of the sixth and final person killed in the collapse was recovered. The victims were originally from El Salvador, Guatemala, Honduras and Mexico.

Two bodies were recovered a day after the collapse, and the rest were found over the weeks following the disaster as crews salvaged the wreckage.