The National Transportation Safety Board (NTSB) released a preliminary report Tuesday about the vessel that hit the Francis Scott Key Bridge nearly two months ago, including details on the ship’s electrical outages and power loss a day prior.
The collapse led to the deaths of six workers who were on the bridge filling potholes during the collision. The estimated cost to replace the bridge is between $1.7 to $1.9 billion, with a projected completion day of fall 2028.
The NTSB worked with the Maryland Transportation Authority, Synergy Marine Group, Grace Ocean Private Limited, Federal Highway Administration, Association of Maryland Pilots, Nippon Kaiji Kyokai, HD Hyundai Heavy Industries, and Maritime and Port Authority of Singapore on the investigation.
NTSB investigators on the cargo vessel Dali, which struck and collapsed the Francis Scott Key Bridge on March 26. The preliminary investigation report came out May 14. NTSB investigators on the cargo vessel Dali, which struck and collapsed the Francis Scott Key Bridge on March 26. The preliminary investigation report came out May 14. Peter Knudson/NTSB
Timeline of how bridge collapse unfolded
The Dali, a 947-foot-long Singapore-flagged cargo vessel, was moving out of the Baltimore Harbor shortly before 1:30 am on March 26. It contained 4,680 containers of cargo and was headed to Colombo, Sri Lanka.
The captain reported the ship was in working order during the master/pilot exchange, according to the preliminary report.
The Dali was assisted by two tugboats.
When the boat pulled away from the dock, all three steering pumps, which turned the ship’s single rudder, were online and two generators were supplying electrical power.
At 1:25 a.m., the Dali was 0.6 miles, or three ship lengths, from the Francis Scott Key Bridge when “electrical breakers that most of the vessel’s equipment and lighting unexpectedly opened (tripped),” according to the report.
“This caused the first blackout (loss of electrical power) to all shipboard lighting and most equipment, including the main engine cooling water pumps (which controlled engine cooling water pressure) and steering gear pumps,” the report reads.
The two generators continued to run, but the voyage data recorder lost vessel system data feeds.
The loss of power made the engine automatically shut down which resulted in the vessel losing main propulsion.
At 1:26 a.m., the voyage data recorder resumed recording data.
The crew manually closed the breakers and reconnected the generator, according to the report. This supplied power to the entire vessel again.
After regaining power – it happened again
At 1:27 a.m., the senior pilot ordered an anchor to be dropped. The pilot’s dispatcher called the MDTA Police duty officer and relayed that the Dali had lost power.
The dispatcher notified the Coast Guard.
Even though the crew restored electrical power, when the ship was 0.2 miles from the bridge, a second electrical blackout occurred. The breakers opened again causing a total loss of power, according to the report.
About 31 seconds after the second blackout, the crew manually restored the power.
AT 1:29 a.m., the Dali struck the pier of the Francis Key Bridge at 6.5 knots, or about 7.5 mph.
“The crew regained electrical power before the vessel struck the pier but was unable to regain propulsion,” the report reads.
The toll of death and destruction
The bridge snapped in several places and collapsed into the Patapsco River.
Pier No. 17, the one the Dali struck, had been surrounded by a 100-foot by 84.5-foot crushable concrete box and timber fender system.
A seven-person road maintenance crew working with the MDTA along with an inspector were on the bridge when the ship struck it.
The inspector escaped unharmed, according to the report. One of the construction crewmembers also survived, but they had serious injuries.
The bodies of the six fatally injured construction members have been since recovered.
One of the 23 people aboard the Dali suffered minor injuries when trying to escape the debris.
The day before the fatal collision
The day before the fatal collision, the Dali experienced a blackout about 10 hours before it left Baltimore on March 25, according to the report.
“While working on the diesel engine exhaust scrubber system… a crewmember mistakenly closed an inline engine exhaust damper,” the report reads. “Closure of this damper effectively blocked the engine’s cylinder exhaust gases from traveling up its stack and out of the vessel, causing the engine to stall.”
NTSB investigators on the bridge of the cargo vessel Dali, which struck and collapsed the Francis Scott Key Bridge on March 26. The preliminary investigation report came out May 14. NTSB investigators on the bridge of the cargo vessel Dali, which struck and collapsed the Francis Scott Key Bridge on March 26. The preliminary investigation report came out May 14. Peter Knudson/NTSB
After the crew manually closed the breakers, insufficient fuel pressure caused the vessel’s speed to decrease and a breaker to open again. Another blackout happened March 25.
“The NTSB is still investigating the electrical configuration following the first
in-port blackout and potential impacts on the events during the accident voyage,” the report reads.
Major marine casualty
The US Coast Guard classified the March 26 accident as a major marine casualty.
The designation of major marine casualty is given if a situation includes the loss of six or more lives; the loss of a mechanically propelled vessel of 100 or more gross tons; property damage initially estimated to be $500,000 or more; or a serious threat to life, property or the environment as determined by the Commandant of the Coast Guard.
Almost 60 of the 4,680 containers on the vessel contained hazardous materials. The NTSB identified 14 of those that may have been damaged when the bridge was struck.
There have been 23,814 marine casualties reported between January 2014 and December 2022, according to the European Maritime Safety Agency. The annual average is 2,646 reports.
What happens next
The NTSB will continue to evaluate the design and operation of the Dali’s power distribution system.
The group is also working with parties to assess bridges and determine if pier protection needs to be improved.
Preliminary costs for the reconstruction of the bridge are estimated to be between $1.7 to $1.9 billion, with a projected completion date of fall 2028.
On Monday, a controlled demolition of the largest remaining steel span was removed.
The span landed on the Dali’s bow, keeping the ship stuck among the wreckage since the crash.
The controlled demolition will allow for the Dali to refloat and be brought back to Baltimore’s port. Once the ship is removed, maritime traffic can return to normal.