Due to incorrect cable labeling, the cable had not been fully inserted into the terminal block, resulting in a loose contact in the high-voltage distributor of the approximately 300 m long ship.
As a result, a high-voltage circuit breaker opened, causing a complete blackout with loss of propulsion and steering.
At around 1:25 a.m. local time, 45 minutes after leaving the port, the “Dali” suffered a loss of power and propulsion in the shipping channel. The crew tried to restore propulsion, but only succeeded for a short time. A short time later, however, the power failed a second time. After only three minutes, the “Dali” collided with the important city bridge, causing it to collapse and killing six construction workers.
In addition to the immediate cause, the NTSB identified other safety deficiencies, including an engine configuration risk with insufficient cooling water pressure and a lack of redundancy in the power supply. The authority also emphasized the structural “vulnerability” of the bridge, which opened in 1977, to large seagoing vessels, a risk that should have been assessed years ago.
According to the NTSB, the damage to the ship amounts to over 18 million dollars, while the cost of rebuilding the bridge is between 4.3 and 5.2 billion dollars. Completion is planned for the end of 2030 at the earliest.
As part of the investigation, the NTSB sent letters to 30 bridge owners in the USA to ask them to reassess the risk posed to their structures by today’s significantly larger ships. In total, the agency formulated 18 new safety recommendations, including to the US Coast Guard, the ClassNK classification society, standardization bodies, shipbuilders, operators and bridge owners. The focus is on improved electrical maintenance, more redundancy in main drives, optimized emergency communication and technical protective measures for bridges.
