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Monthly Image: Belmar Bridge

About five miles south of Franklin PA along the Allegheny River Trail, the Belmar Bridge carries the Sandy Creek Trail over the Allegheny River:

Belmar Bridge - Rivets

Belmar Bridge – Rivets

The gap in the rivets along the main truss show where someone pried off the bronze plaque surely commemorating the bridge. The scarred surface suggests a bronze-steel battery was in effect for quite some time.

I’m a sucker for big ironwork:

Belmar Bridge - Truss Joint

Belmar Bridge – Truss Joint

It’s a look at engineering done in the days of slide rules and limited data, when overengineering wasn’t nearly as bad as ensuring the thing never, ever fell down.

The bolts holding the beams and struts together show considerable confidence:

Belmar Bridge - Ironwork - bolt detail

Belmar Bridge – Ironwork – bolt detail

Each bolt counts as single point of failure, but this one can rust for a long, long time before the risk becomes important.

Each of those gazillion rivets required a crew to heat white hot, shove into the hole, and hammer tight.

They don’t make ’em like that any more and I suppose it’s a good thing …

 

 

 

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