Loose Wire on Containership Dali Causes Blackouts, Contact with Baltimore Bridge

ntsb.gov

11 points·hyperrail··4 comments

All the commentary, and this report, keeps saying how the bridge was built before ships got this big.

But why do ports & municipalities allow ships that are too large for them to handle?

The bridge was already hit in 1980 and shrugged it off, so the bridge was safe for ships up to some size. Surely the engineers had the numbers to estimate what a safe maximum size would be. So it seems like a ship like that just shouldn't have been allowed in the area in the first place.

If your truck is too heavy for a little wooden bridge, you aren't allowed to drive the truck over it.

> why do ports & municipalities allow ships that are too large for them to handle?

Fees and relevance.

And the loose connection was caused by a misapplied wire label that made the wire too fat to properly fit the connection...

It sounds like the fault from the bad termination tripped an upstream overcurrent protection device first instead of the local overcurrent protection device, which would’ve taken down more of the electrical system than necessary.

Electrical engineers perform breaker coordination studies to figure out the proper trip rating settings in an electrical distribution network so that the most local overcurrent protection device trips before any upstream devices. A 120V 20A circuit breaker in a hospital might have three or four (or more) overcurrent protection devices between it and the utility transformer.

It is possible that with correct breaker trip settings that this accident could’ve been avoided, but I would need more information than is given in the article to tell.

ABB coordination study pdf: https://library.e.abb.com/public/06f0ad870bda4dd7b47f71699d9...

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