DEMOLITION | Francis Scott Key Bridge Collapse Truss Separation | 4K VIDEO

00:00 Intro
01:07 Prep Work
04:50 Demo
At 1:28 AM on March 26th, the container vessel, MV Dali, lost power while proceeding south on the Patapsco River out of the Baltimore, Maryland Harbor. The starboard shoulder of the bow impacted the southern channel pier of the Francis Scott Key Bridge causing collapse of the pier and progressive failure of the entire 2,640’ long continuous truss that spanned the two (2), 720’ wide approaches and the 1200’ wide main channel that accommodated vessels having up to a 50 draft.
The collapse of the bridge tragically caused the deaths of six (6) workers performing maintenance on the bridge deck and resulted in the closure of one of the busiest ports in the US, putting an estimated 4,000 port employees out of work while impacting another 15,000 Baltimore residents who relied on port activities for their livelihood.
The City of Baltimore, State of Maryland and Federal Government immediately joined forces toward reopening the channel as quickly as possible under a Unified Command structure led by the US Army Corps of Engineers. The Federal government assumed responsibility for clearing debris from the 1200’ wide main channel, Skanska was tasked with debris removal responsibilities outside the main channel and Resolve Marine of Fort Lauderdale, Florida was retained by the ship Owner and its Operations Company to remove debris that had fallen on the bow of the ship and to salvage the vessel.
Resolve Marine retained Controlled Demolition, Inc. (CDI) to design, perform preparations for and carry out explosives separation of the 600’ long southern portion of the channel-span truss from the bow of the Dali.
The bridge truss, pier cap and roadbed debris fell vertically onto the bow of the vessel and the continued motion of the ship caused the truss to twist, adding additional stored energy to the already compromised bridge truss system. CDI’s scope to separate the truss from the ship included preparatory pre-burning operations that would identify and then cope with the stored energy in the box configuration and other truss elements that had flange thicknesses up to 4” thick to be severed with explosives. Strain gauges and other monitoring devices were installed to provide real time readings on truss stability so that pre-burning could be paused as necessary to ensure CDI employee safety.
CDI’s goal was to provide a 60’ wide space between the vessel and the remaining truss, in the water, while rolling as much of the truss as possible off of the bow of the Dali during the explosives initiation sequence. The presence of flammable materials in containers damaged by the bridge collapse necessitated cold cutting for preparation of shaped charge locations where hot work couldn’t be safely performed. Cold cutting could not be completed on all elements above the bow due to the energized truss elements, leading to a plan that would leave a small portion of the truss on the bow and other truss elements draped over the port side for post-blast crane removal.
Preparatory burning was carefully monitored by CDI and structural engineers and the sequence/nature of pre-burning was changed several times following twisting observed in bridge elements during torch work. Working out of 185’ manlifts and crane baskets proved challenging on the water due to wave action, winds and weather that limited working hours. Even as they otherwise prepared to re-float the vessel, Resolve Marine provided marine platforms/equipment to support CDI’s operations toward removing the truss from the Dali as quickly as was safely possible.
A total of 162 pieces of Linear shaped charge explosives were placed at 52 locations with a NET explosives weight totaling 312.69 lbs. of RDX and PETN explosives to create the separation between the truss and the vessel and to permit as much of the truss to rotate off the bow as possible during the blast. Conveyor belt at-source protection was placed by CDI to control the fly of debris from the detonation of the explosives charges.
Once the Unified Command cleared the CDI specified Exclusion Zone around the blast area, Resolve Marine turned on a water fire suppression system over the damaged containers at the bow to mitigate risk of fire.
The Dali crew was sheltered below decks at the stern of the vessel in a soundproofed area during the blast while Resolve Marine and CDI employees positioned themselves at the stern of the vessel during the explosives detonation. The non-electric initiated blast had an integral 9.6 millisecond delay directing the pressure bar away from the vessel and the windows in the bridge which represented the most sensitive element to remain on the vessel.
The charges were detonated at 5 PM on May 13th. The separation was completed, and that portion of the truss intended to roll off of the bow, did so, exactly per plan. There was no reported damage to the vessel, or its cargo and no fire was initiated on the vessel as a result of CDI’s operations.