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From: Don Y <blockedofcourse@foo.invalid>
Newsgroups: sci.electronics.design
Subject: Re: Full video of ship hitting and destroying the Francis Scott Key
 bridge in Baltimore
Date: Fri, 29 Mar 2024 04:50:35 -0700
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On 3/29/2024 4:18 AM, Martin Brown wrote:
> The bridge was *designed* to fail catastrophically if anything hit one of its 
> main supports which is unforgivable on a bridge that is over a waterway leading 
> to one of the busiest Atlantic ports in America.

I would reword that as your presentation suggests this flaw was a
"design goal".

Rather, the design chosen *suffered* from the vulnerability that a single
such incident would result in a catastrophic failure.

The design also included measures that were intended to minimize the risk
of this happening.

> Most big bridges in first world countries have buffer islands and underwater 
> structures to deflect and/or slow a large vessel to prevent them from impacting 
> any of the key support structures near a live shipping channel. The ship may 
> ground and be damaged and the bridge shaken by that impact but that should be 
> about the limit of what can happen to a properly designed bridge in these 
> circumstances.

The bridge had some such protections -- likely deemed adequate when it
was designed (it was opened in 1977 and thus *designed* years earlier).
But, more "adequate" (given *this* traffic) protections may have constrained
river traffic (as they consume resource IN the shipping channel) or been
deemed overkill at the time of the design.

Guesstimating how much margin to factor into each design decision is
always a crap shoot as prescience is not a science, despite the spelling!  :>

Do you (legislatively) restrict the shipping traffic to ensure it never
puts the existing design at risk?  At what cost to the economy, that?

> Also it can take a very long time to alter course with a large vessel.

That.  Esp when it comes to commercial vessels, the "rules of the road"
(river?) implicitly acknowledge this in that the stand on vessel is almost
always the one that is least able to make quick changes to its course or
progress.

> The ship issued a Mayday which saved lives by closing the bridge to new traffic 
> before the impact but it was very sad for the road crews working on the road deck.