What happened
On March 26, 2024, the container ship Dali lost electrical power twice in the minutes after leaving Baltimore harbour, lost propulsion and steering, and drifted into a support pier of the Francis Scott Key Bridge. The bridge’s central span collapsed within seconds. Six highway workers on it were killed.
What investigators eventually traced it to
In November 2025 the NTSB named the root cause: a single mislabelled wire, installed during the ship’s construction years earlier, that intermittently failed to make contact inside a circuit breaker. That one loose connection was enough to black out the ship at the exact moment it needed power to steer clear.
The bridge’s side of the failure
The NTSB’s other finding was about the bridge, not the ship: Key Bridge had never had a vulnerability assessment against being struck by a ship of that size, and investigators found its risk of collapse from a collision was far above the accepted threshold, a gap that existed long before Dali ever left port, and that nobody had closed.
A single point of failure that brings down an entire structure (one wire on a ship, one pier with no redundancy built around it) is precisely what a structures course spends its time on: load paths, and what happens when there is only one.
Structures EngineerStatics & Structural Forces: Engineering Foundation