Fabius Creek Bridge on Fawn Avenue
Photo taken by Chris Gonnerman in April 2012
License: Creative Commons Attribution-Share-Alike (CC BY-SA)
BH Photo #229167
I see your point. Note that the center diagonals are technically compression rather than tension members; this is consistent with a Warren truss. I still suspect the bridge builder had looked at some Thacher-derived trusses when designing this one... those center diagonals look almost exactly like the ones I've seen on the Thacher derivatives. Parts-wise, it's a bit of a mashup.
So I'll change the truss description to correspond to that type.
Yeah...just a Warren with verticals and unusually heavy diagonals in the center panels.
This again proves that I shouldn't look at (and comment on) truss types when I am tired!
The Thacher truss is, as I understand, characterized by diagonal members that are not parallel to each other. The eyebar/tension diagonals would be expected to be longer in length than the built-up compression diagonals, as I found to be the case with the Ellsworth Ranch Bridge mentioned below. This Fabius Creek Bridge does not appear to display these characteristics. The only thing "out of order" that I observe on this bridge is that the center vertical member appears to be an eyebar/tension member, which is off. But aside from that, wouldn't this bridge just be a pin-connected Warren truss? It looks like the Dietzenbach Bottom Bridge http://www.historicbridges.org/bridges/browser/?bridgebrowse...
Just a bit more, if you don't mind. I found the information about Thacher trusses (particularly the patent situation) here:
Actually, now that I've looked up Thatcher trusses, I realize that this is just another modification of the type. According to some information I found on a few other sites, the Thacher truss was patented, and no examples of the actual patent-original design still exist; but apparently, "almost" copying the design wasn't that uncommon. I'm guessing the bridge builder, taken with the Thacher design, used common Pratt components at the ends but swapped the usual crossing eyerods with Thacher-style braces in the middle two panels.
Is this enough, do you think, to reclassify this as a Thacher truss for purposes of this site?
This bridge almost looks as though someone took a Thacher truss and tinkered with it and this was the result...very interesting!
I don't know what to make of this bridge. On the surface it looks like a common pin-connected Pratt truss, but the angled members in the center two panels are rigid and arranged to bear both tension and compression loads (as in a Warren truss).
I called it a Pratt, but I'm not at all sure that's correct. But it's sure cool.