MAYDAY

In the early morning of March 26, 2024, crew aboard Motor Vessel DALI issued the mayday call moments before the crash that took down the Francis Scott Key Bridge, enabling authorities to limit vehicle traffic on the span. The collapse of this pivotal piece of infrastructure sent eight construction workers into the Patapsco River below, taking the lives of six of them.

The cargo ship departed the Port of Baltimore around 12:40 a.m. for what was expected to be a journey to Sri Lanka. Shortly after leaving the terminal, M/V DALI lost power and struck one of the Key Bridge’s support pillars. Within seconds, almost a mile of the 80-foot-wide bridge crumbled, falling into the water below. One section, roughly 500-feet long, 80-feet wide, and weighing 400-600 short tons, fell onto the M/V DALI’s bow, pinning the ship to the federal channel.

The federal Fort McHenry Channel, now blocked by wreckage and M/V DALI, is operated and maintained by the U.S. Army Corps of Engineers (USACE), Baltimore District, authorized by Section 101 of the Rivers and Harbors Act of 1958 and the Water Resources Act of 1996. The channel is regularly surveyed and dredged to its authorized depth of 50-feet and a minimum width of 700 feet.

With the channel blocked by the M/V DALI, wreckage, and debris, ships could no longer pass through the Port of Baltimore – creating a catastrophic ripple in economic impact both locally and beyond.

The Port of Baltimore is the ninth-busiest port in the country for international cargo, and the seventeenth-largest overall. In fiscal year 2023 alone, the public terminals handled nearly 12 million tons of general cargo, while also handling another 52.3 million tons of international cargo – both numbers setting a record for the facility.

THE RESPONSE & UNIFIED EFFORT

USACE, Baltimore District activated its Emergency Operations Center (EOC) on March 26 in an immediate response to the collapse. With the activation of the EOC, engineering, construction, contracting, and operations specialists from around the district began the complex process of clearing the wreckage and debris from the bridge to restore safe navigation in and out of the Port of Baltimore.

Simultaneously, both Maryland and City of Baltimore officials declared a state of emergency allowing state and local resources to be directed to the response.

The Unified Command was formed to carry out the response, consisting of six agencies and organizations: USACE, U.S. Coast Guard, Maryland Department of the Environment, Maryland Transportation Authority, Maryland State Police, and Witt O’Brien’s, representing Synergy Marine.

While the exact number of responders flowed and ebbed since the bridge collapse, more than 350 uniformed and civilian workers from 53 federal, state and local agencies from all corners of the U.S. deployed in Baltimore for the recovery and salvage effort. Including an additional 553 contract specialists currently serving in a diverse variety of jobs related to activities like dive, crane and vessels operations, more than 1,200 people have contributed to the Key Bridge Response mission.

“We have marshalled incredible skills and the best equipment available,” said Baltimore District Commander Col. Estee Pinchasin. I am fully confident that we have the right team and partners in place to tackle this project and do what we do best – serve and strengthen this great Nation.”

The Unified Command identified three concurrent salvage operation priorities to be met in order to restore the Port of Baltimore to normal operations at the initial stage of response.

Priority 1: Clear the Channel (the Federal Channel

and Priority 1A, the Limited

Access Channel)

Priority 2: Refloat the Vessel (Moving the M/V

DALI out of the Federal Channel)

Priority 3: Remove the Remaining Wreckage

“We continue to provide our best talent and technology in support of the Coast Guard and our local, state and federal partners, said Lt. Gen. Scott. Spellmon, USACE Commanding General.

USACE contributed its unique technical expertise and abilities to the Unified Command team in support of accomplishing these three priorities. The top USACE asset is its people. Other USACE capabilities included certified underwater assessments, structural engineering, bridge inspections, contract support and waterway wreckage management – all facilitated by advanced hydrographic and topographic sonar tools on its fleet of highly-specialized survey vessels.

ENGINEERING SOLUTIONS FOR THE NATION’S TOUGHEST CHALLENGES

On March 30th, removal of the Francis Scott Key Bridge wreckage commenced with assistance from 56 federal, state, and local agencies, represented by 1,587 individual responders. Additionally, about 500 specialists from around the world operated a fleet of 36 barges, 27 tugboats, 22 floating cranes, 10 excavators, and four survey boats. Subject matter experts from all over the U.S. also provided essential technical knowledge to the Unified Command.

Clearing the wreckage from the Fort McHenry federal channel posed a series of extremely complex and unique challenges. The total weight of the steel and concrete wreckage across the total collapsed span was estimated at 50,000 short tons, equivalent to 100 million pounds – or roughly 3,800 fully loaded dump trucks.

“The U.S. Army Corps of Engineers is responsible for engineering solutions to our nation’s toughest challenges, and this disaster constitutes one of those top challenges,” said Lt. Gen. Scott Spellmon. “It requires a deliberate, diligent engineering strategy, based on careful assessments of the disaster site, and with safety as our top priority.”

USACE Baltimore’s Navigation teams sprang into action. Survey Vessel CATLETT and Debris Vessel REYNOLDS both took to the water and provided their expertise. S/V CATLETT provided sonar imagery of debris beneath the waterline and D/V REYNOLDS removed smaller debris from the waterway. Both vessels were an invaluable asset to the initial Key Bridge collapse response.

Advanced imaging technologies such as LIDAR, sonar, and PhoDAR allowed engineers to get a picture of the positioning and location of the wreckage underwater. However, they couldn’t rely on technology alone as some elements of the wreckage might not be detected. Physical divers in the water to survey the wreckage was paramount.

Under an interservice agency agreement, USACE worked in a joint effort with the U.S. Navy’s Supervisor of Salvage and Diving (SUPSALV) to oversee the commercial dive companies performing the work underwater. There were three overarching steps to the underwater salvage response:

Step 1: Survey and map the underwater hazards

Step 2: Develop and execute the salvage plan

Step 3: Safely execute the salvage work. It was

an iterative process that was repeated

after each removal.

To ensure the safety of the divers, they were restricted in how long they can be in the water due to water temperature pressure.

“The response to the Francis Scott Key Bridge collapse is an unusual mission with an uber-extreme work environment of dark, cold water. Beneath those waters, divers are moving as if playing an underwater game of Twister and Jenga with hundreds of tons of shattered concrete and twisted steel in complete darkness,” said Rick Benoit, USACE North Atlantic Division, Emergency Management Specialist. “If divers fail, the price of failure could be severe injury or death; safety must be the top priority at all times.”

A total of 79 missions operated by Unified Command to gather sonar and laser images for mapping the wreckage and safe transit routes and 109 dive missions, not including those that were performed during the initial 48 hours after the collapse, were completed. Once the wreckage and debris beneath the water’s surface was assessed, removal could begin.

Some of the largest floating cranes on the East Coast were brought in to help remove the wreckage – including a 1,000-metric-ton hydraulic wreck grab that is attached to the Chesapeake 1000 crane and capable of lifting 1,000 tons of the debris at a time. The grabber on the Chesapeake 1000 is the largest in the United States and even it couldn’t handle some of the wreckage pieces due to their size and weight. The pieces had to first be cut down to be moved.

The immense tension in the steel created numerous potential hazards. When one piece was moved, the pieces around it were affected and could potentially move on their own. The team analyzed the steel and anticipated how the secondary pieces would move to prepare for the mitigation of additional potential hazards.

“When the bridge fell, it created a lot of force on the steel. There’s a lot of compression and tension,” said Brig. Gen. John Lloyd, commander of the USACE-North Atlantic Division. “I think everybody that I talk to realizes the magnitude of this. It is certainly unprecedented; you don’t realize the scale in photos and videos.”

The wreckage throughout the clearing of the channel was transported to Sparrows Point for follow-on processing.

LIMITED ACCESS CHANNEL

One of the first major milestones occurred the week of April 22 when the Limited Access Channel opened, meeting Unified Command’s Priority 1A.

USACE had enough wreckage cleared to establish the 35-foot-deep Limited Access Channel (LAC), in accordance with USACE’s commitment to deliver it by the end of April. The LAC ran the northern portion of the wider federal channel and had a 300-foot horizontal clearance. Over the next couple of weeks, it was deepened to 48 feet deep.

“We’re working to strike a balance between enabling temporary access to support commercial activity and undertaking necessary measures to fully reopen the Fort McHenry Channel,” said U.S. Coast Guard Capt. David O’Connell, Captain of the Port and Federal On-Scene Coordinator.

“This limited access deep draft channel will provide a window for five of the deep draft vessels currently unable to depart the port as well as some smaller deep draft vessels to transit. Meanwhile, the Unified Command personnel continue to work full speed ahead to safely and efficiently finish operations.”

During the clearing of debris, all six remaining construction workers were located, and their families were notified by Maryland State Police.

“Each day we thought of those who lost their lives, their families, and the workers impacted by this tragic event,” said Col. Pinchasin. “Not a day went by that we didn’t think about all of them, and that kept

us going.”

REFLOAT THE VESSEL

With the Unified Command’s Priority 1 completed, the team was immediately on to the next mission priority of removing M/V DALI from the channel.

Priority 2 also had to be completed in stages and posed its own challenges. The first phase took place simultaneously during the clearing of the LAC. Containers needed to be removed from the ship to lessen the weight and lift the vessel up off the riverbed. This process began on April 7, and the weight and balance of the M/V DALI were assessed throughout.

“The removal of the containers is a critical step required to safely move the M/V DALI and eventually fully reopen the Fort McHenry Channel,” said Col. Estee Pinchasin, Commander and District Engineer, USACE, Baltimore District.

Once 182 of the 4,700 containers aboard the ship were removed, the next phase was to remove the truss, referred to as “Section Four,” that fell on the M/V DALI’s bow during the Key Bridge initial collapse. This piece was laying across the M/V DALI’s bow and into the water, pinning it without movement to the riverbed.

Due to the sheer size of the truss, Unified Command determined a precision cutting technique was the safest and most efficient method of removal.

This industry-standard technique involved the use of small charges that when detonated, create pressure that separates the metal into multiple, smaller and more-manageable sections. Salvors pre-cut the truss at strategic locations determined by engineers and small metal-covered explosive cores were placed inside the cuts. Many of these smaller pieces would fall into the water where salvors later used the cranes and barges already on scene to remove them.

A notice of detonation went out to the public in advance, and the charges were detonated on May 13. The detonation first appeared as a bright flash with several puffs of smoke with the sound, similar to a short round of fireworks, coming seconds later.

The refloat and transit sequence was deliberately designed to ensure the refloat crews and support personnel around the M/V DALI remained in complete control of the vessel and its movement to the Seagirt Marine Terminal.

“You want the ship to move on your terms, not its terms. If a ship is made too light, too fast, it could jolt upward and swing around uncontrolled, potentially damaging its hull by bumping into a piece of debris. The last thing you want to do is knock a hole in the ship,” said Mike Dean, Executive Director, American Salvage Association.

The entire refloat sequence began roughly 18 hours beforehand, on May 19. Some of the vessels anchors and mooring lines were released, with nearby tugboats on standby; de-ballasting of part or all of the 1.25 million gallons of water pumped onto the ship, to compensate for the weight removed during the controlled demolition; and detailed inspections confirming all obstructions had been removed on the left side of the M/V DALI by Unified Command dive survey teams and the USACE Baltimore District Survey Vessel CATLETT.

With the weight removed from the bow of the ship, and the refloat sequence steps complete, M/V DALI was refloated and moved by Unified Command on Monday, May 20 around 7 a.m. With the assistance of five tugboats and other support vessels, the vessel was towed and pushed 2.5 miles, arriving at a local marine terminal around 9 a.m. This milestone allowed all pre-collapse, deep-draft commercial vessels to enter and exit the Port of Baltimore for the first time since April 26.

With the removal of the M/V DALI, Unified Command salvage crews, using crane and barge assets already on-site worked to remove the remaining wreckage and debris from the water.

MISSION COMPLETE

On June 4, the last major piece of steel truss was removed from Federal Channel and on June 10 – just 76 days from the Francis Scott Key Bridge collapse – the U.S. Army Corps of Engineers and U.S. Navy Supervisor of Salvage and Diving restored the Fort McHenry Federal Channel to its original operational dimensions of 700 feet wide and 50 feet deep for commercial maritime transit through the Port of Baltimore.

Following the removal of wreckage at the 50-foot mudline, the Unified Command performed a survey of the Federal Channel June 10, certifying the riverbed as safe for transit.

“We’ve cleared the Fort McHenry Federal Channel for safe transit. USACE will maintain this critical waterway as we have for the last 107 years,” said Col. Estee Pinchasin, Baltimore District commander. “I cannot overstate how proud I am of our team. It was incredible seeing so many people from different parts of our government, from around our country and all over the world, come together in the Unified Command and accomplish so much in this amount of time.”

Throughout this mission, USACE Baltimore’s overarching goal was to restore full operational capacity to the Federal Channel. With the assistance and support that was received from the partnerships within the Unified Command, USACE was successful in ensuring the safety of the public and first responders, accountability of missing persons, protecting the environment, incident stabilization, safely restoring transportation infrastructure and commerce, and supporting the investigation.

“Estee, we salute you and the Baltimore team,” said Maj. Gen. William (Butch) Graham, USACE Deputy Chief of Engineers and Deputy Commanding General. “Mission accomplished. Well done.”