Looks like the designer couldn't decide on a truss bridge or an arch bridge, so he used both. I wonder how long a timber bridge like that lasted. Looks like pine from Virginia, not exactly a durable timber. The rods would have been cast iron, so would have outlasted the wood.
hokie66 - it's actually called a Burr Bridge after Theodore Burr; a combination arch & truss.
If you're ever in the Allentown PA vicinity, go to Covered Bridge State Park. There are two well preserved Burr Bridges from the 1850's - and still open to traffic.
We just completed a bridge much like the one in the photo. Ours was a 128' single span. All timber. HS20 loading. The only steel in it was the bolts and plates at the connections.
Those were some fun shop drawings to check.
Anybody else besides me astonished at the sharpness of this picture? You can pick out grain directions on some of the beams. Most pictures I've seen from that era are blurry (and yes, I know what causes that!); but this one is very sharp.
Aren't a bunch of the surviving covered bridges around the US made with the Burr design? Many aren't open to traffic, but many still are (for instance, western Indiana). Remarkable design-use the natural strength of the arch, combined with the practicality of a standard truss design. Does the bridge collapse without the arch?
