On 13 May, Key Bridge Unified Command used precision blasts to cut the bridge sections resting on top of the container ship Dali into smaller pieces. Breaking the bridge span into smaller pieces will allow refloating the vessel and removing it from the federal channel.

On 26 March, the container ship Dali left the Port of Baltimore headed for Colombo. Shortly after departure, the ship lost propulsion and allided with the Scott Key Bridge, which subsequently collapsed. The ship’s crew were reported safe, but eight road workers were working on the bridge when it collapsed. Two were rescued from the water, the bodies of the other six were recovered later, with the last found and recovered on 7 May.

Legal tactics have already been put into play with the owner and manager, Grace Ocean and Synergy Marine respectively, seeking to limit their liability. In response, the City of Baltimore has asked the court to not grant this limitation and claims the vessel left the port in an unseaworthy condition.

Also read: Baltimore claims container ship Dali was unseaworthy before bridge allision

Using small charges

Since the bridge collapsed a large bridge section has been resting on top of the Dali’s bow, pinning it in place. Teams have strategically removed 182 containers from the ship to facilitate the removal of the piece of steel structure, referred to as “section four”.

According to Key Bridge Unified Command, the safest and swiftest method to remove the bridge piece from on top of the M/V Dali is by precision cuts made with small charges. This is an industry-standard tool in controlled demolition. It was used yesterday and succeeded in breaking the bridge span into smaller pieces.

Also read: Salvage crews preparing for removal of bridge piece on top of Dali

Monitoring the ship

Specialised equipment has been employed to closely monitor the positioning and movement of the M/V Dali and the bridge wreckage in contact with it, also during the operation.

Last week, as the salvage teams were preparing for the removal of the bridge piece on top of the Dali, Rob Ruthledge, a contractor working for the Key Bridge Unified Command, said: ‘We’ve got a total of six of, what we call, inclinometers that measure tilt on key locations of the span and key locations of the ship so we can watch how it’s pitching and rolling with tide, and wind. We have a sensor measuring the relative position of the span on the ship so we can see, if for some reason, it starts to slip. We also have what are called string gauges, which can measure, in real-time, the stress, while they are performing operations.’

Picture: Salvors with the Unified Command perform a controlled demolition, precision cutting of section 4 of the Francis Scott Key Bridge that sits on the port side of the bow of the M/V Dali, 13 May (photo by US Army Corps of Engineers/Christopher Rosario).

Also read: What happened in the minutes leading up to the Key Bridge collapse