Baltimore & Ohio Railroad Bridge

Pennsylvania , Baltimore, Whipple and Pratt trusses are the most confusing to count for me. Just a lot of action going on.

Pratts are confusing due to the arrangement of the sway bracing.

Funny this discussion is going on a page named for the Baltimore and Ohio Railroad, since most people mis-count panels when they don't count the subdivided panels on Baltimores (and Pennsylvanias) for examples. These subdivisions were intended to increase the number of floorbeams and thus reduce the depth (and weight) of deck stringers. If you are curious for an example of one of the "odd situations" Mike mentioned, one that comes to mind is a bridge in Ontario which features a floorbeam at each bottom chord batten plate... a strange arrangement that I suspect was intended to minimize the depth of steel underneath the deck for flooding issues. https://historicbridges.org/bridges/browser/?bridgebrowser=o...

On most trusses the triangles do tell you how many panels. It is just trusses like this no vertical Warren and the Baltimore, Pennsylvania and Whipple trusses that can get confusing at times.

Keep asking those questions and learning.

Oh OK. I was going by the triangles shapes. I wonder how many bridges have been miscounted on or have been categorized wrong, as I thought I had labelled a bridge as a Warren through truss with all verticals, but it is labelled on here as such.

Brandon,

I think you are starting to get if figured out, you just counted on the wrong side of the truss. As Nathan said, the floor beams pretty much dictate your panel numbers, except in odd situations. Check out this graphic for the bridge, hopefully this helps out.

I think I might be figuring it out. I tried my favorite railroad bridge, and it looks like I count 3 panels, as I counted the solid bars. https://bridgehunter.com/oh/muskingum/bh37139/

I think I got this particular bridge figured out. I see 4 triangle sections that look a little more rigid and have more building material than the other three sections.

Baltimore trusses and Pennsylvania trusses are ultra complex and just baffle my mind, especially Pennsylvania trusses. They are intimidating, even more so on a railroad structure as they are just tall and ungainly looking.

That approach works best. Where people get tripped up on panel counts is when they fail to count the subdivided trusses properly and they only count the gaps between full vertical members. On Baltimores and Pennsylvanias the shorter vertical lower chord connections must be counted too. That is the essence of what subdivision does... adding panels (and thus floorbeams) to reduce the length (and thus depth) of deck stringers, resulting in overall weight reduction.

By the number of segments in between connection points on the lower chord - in this case, four. Usually the part of a truss in between two vertical members is considered a panel...not in the case of this bridge, however, as there are no verticals!

It's easier to see on a bridge like this one, which has 11 panels: http://bridgehunter.com/oh/ashland/hog-hollow/

Not sure how good of an explanation that was, but hope it helps!

How does one count the panels on a truss bridge?

Historic aerials show that this bridge was removed without replacement between 2011 and 2013 and the road re-routed along the south side of the railroad tracks to avoid crossing them.

Listed on ODOT site as being available for reuse

http://www.dot.state.oh.us/divisions/transsysdev/environment...