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NTSB Preliminary Report on Baltimore Bridge Collapse Released

Photo courtesy NTSB

NTSB Preliminary Report on Baltimore Bridge Collapse Released

Mike Schuler
Total Views: 2625
May 14, 2024

The National Transportation Safety Board (NTSB) has published its preliminary report into the catastrophic incident involving the Singapore-flagged cargo vessel Dali and the Francis Scott Key Bridge in Baltimore on March 26, 2024.

The collapse effectively closed the Port of Baltimore to ship traffic, before salvage crews were able to open temporary channels allowing for limited navigation in and out of Baltimore Harbor.

According to the report, which does not include any analysis or conclusions, the Dali lost electrical power and propulsion as it approached the bridge, causing it to strike the bridge and resulting in a portion of the bridge collapsing. Critically, the ship also lost electrical power twice the day before the accident.

Seven road maintenance crew members and one inspector were present on the bridge during the incident. Tragically, six crew members lost their lives, one survived with severe injuries, while the inspector escaped unscathed. A crew member aboard the Dali also sustained minor injuries.

The U.S. Coast Guard has classified the accident as a major marine casualty, with the NTSB leading the safety investigation.

The preliminary report chronologically traces the events leading up to the accident, as well as efforts to stop the ship and alert authorities ashore to the danger.

At about 0005, a senior pilot and an apprentice boarded the Dali, which was about to depart from Seagirt Marine Terminal to Colombo, Sri Lanka, carrying 4,680 containers. The captain reported the ship was in good working order during the master/pilot exchange.

The sequence of events quickly took a turn for the worse as the Dali experienced two electrical blackouts during its approach to the bridge.

he Dali’s route on March 26, between the first blackout, and the Dali striking pier no. 17 of the Key Bridge. The location and approximate size of two of the bridge’s “dolphins,” sheet pile and concrete structures protecting the bridge’s piers, are labeled in the lower right.
he Dali’s route on March 26, between the first blackout, and the Dali striking pier no. 17 of the Key Bridge. The location and approximate size of two of the bridge’s “dolphins,” sheet pile and concrete structures protecting the bridge’s piers, are labeled in the lower right.

The first blackout occurred at about 0125 as the ship was approximately 0.6 miles from the Key Bridge, when electrical breakers that fed most of the vessel’s equipment and lighting unexpectedly tripped. This resulted in an automatic shutdown of the main propulsion diesel engine and the halting of all three steering pumps, leaving the vessel traveling at a speed over ground of 9.0 knots without any means of steering or propulsion.

While the Dali’s crew managed to restore electrical power briefly, a second blackout occurred when the ship was only 0.2 miles from the bridge, causing a complete loss of electrical power on the vessel. Despite attempts to restore power and drop anchor, the crew was unable to regain control over the vessel’s propulsion.

The sequence also provided details of the pilots’ efforts to alert others of the dangers in the minutes after the first blackout.

  • The pilots called for tug assist at 0126:39, with the Eric McAllister responding immediately (although it did not reach the Dali before it struck the bridge).
  • At 0127:01, senior pilot ordered an anchor drop after the ship, Dali, lost power. The pilots’ dispatcher informed the MDTA Police duty officer and the Coast Guard about the situation.
  • One of the pilots issued a warning to all waterborne traffic via very high frequency marine radio at 0127:25.
  • At 0127:53, the MDTA duty officer ordered the closure of the bridge to all traffic, leaving only the maintenance crew and the inspector on the bridge.

The Dali struck pier no. 17 of the Key Bridge at 0129:10 while traveling at approximately 6.5 knots, leading to the collapse of six spans of the bridge.

Prior to the Accident

The NTSB report also provided a background on the Dali and key events prior to the accident.

The ship arrived in the U.S. from Sri Lanka on March 19, 2024, and made port calls in Newark, New Jersey (March 19-21), and Norfolk, Virginia (March 22-23), before mooring at the Seagirt Marine Terminal in Baltimore Harbor early on March 23.

In-Port Blackouts

The day before the accident, the Dali had experienced two in-port blackouts, prompting the crew to switch the main electrical bus configuration, which was in use when the ship departed.

The NTSB said the first in-port blackout was caused by the mechanical blocking of the online generator’s exhaust gas stack after a crew member mistakenly closed the an engine damper while working on the ship’s scrubber system. The crew manually restored power and switched the bus configuration to use different breakers (HR1 and LR1) and transformers. The second blackout in port was related to insufficient fuel pressure for the online generator. The NTSB said the first blackout after the ship’s departure was due to unexpected tripping of the breakers HR1 and LR1.

The NTSB is now investigating the electrical configuration and its potential impacts on the accident voyage.

Fuel Testing

As for fuel testing, the Dali switched to low-sulfur marine gas oil (LSMGO) five days before the accident. Post-accident fuel samples taken from the LSMGO in use and from all fuel tanks complied with international standards and regulations, ruling out fuel quality as a contributing factor to the accident.

The release of the preliminary report comes a day after salvage crews used small charges to make precision cuts in the bridge truss sitting on top of the Dali’s bow, which will allow for a refloating attempt to take place sometime this week.

Officials anticipate opening the 50-foot-deep federal channel by next month.

The FBI opened a criminal probe into the collapse in April.

The NTSB’s preliminary report can be found here.

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