Union Pacific Railroad Bridge across Republican River at Junction City, KS
View from the northwest
Photo taken by Phil h
View this photo at panoramio.com
BH Photo #256689
It could be possible that it was a standard design for the railroad, and the portals were used regardless of bridge design? I understand why you would believe it was for a pinned connection. I could see where it was a standard design...
Replacing the portal bracing for height clearance makes sense. I was just always under the impression that portal bracing gaps were designed to accommodate a pin.
Robert,
The trusses along this line originally had the portal bracing similar to the Cloud County structure. I'm guessing it was replaced to increase the size capacity of trains on this line.
Well, never mind. This bridge has a portal bracing gap as well:
The portal bracing on this bridge is not flush with the top of the endpost. Instead, it curves inward leaving a gap between the portal bracing and the endpost. Often this is done to accommodate a pin. You can see this system very well here:
http://bridgehunter.com/ks/butler/bh48844/
Yet, on this railroad bridge is riveted, not pin-connected. Thus, there is no pin that needs to be accommodated by a gap. Could parts of the portal bracing on this bridge have been recycled from a pin-connected bridge?
I personally have never seen a portal bracing gap on a riveted bridge. Has anybody else seen this? Some of you have looked at far more bridges than I have.
That makes sense. Perhaps this design was in fact originally designed to accommodate a pin, but then perhaps it became a standardized design and remained in use even after the railroad transitioned to using rivet connections. Plus, if by chance the railroad or fabricators had some left over portal bracing components leftover why not use them?