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Truss Bridge Placement

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  • Member since
    February 2008
  • 2,354 posts
Truss Bridge Placement
Posted by kasskaboose on Tuesday, December 12, 2023 4:39 PM

Happy Holidays!

Should I keep a handmade truss bridge my 1st mentor gave me in the back corner of the finished layout or put it along one side of my "E" shaped pike? In moving it, I would have to tear up existing ground foam and ballast (track isn't glued down to sub-roadbed).  I know plenty here have done more such work on "finished" layouts.

I carved out and put PoP over an area under the bridge in the back corner.  The other option is order a 2nd truss bridge.  This way I have one bridge in the back corner and another along the side.

Also, are abutments needed for such a bridge or depends on a bridge's length?

Regards!

  • Member since
    December 2004
  • From: Bedford, MA, USA
  • 21,442 posts
Posted by MisterBeasley on Tuesday, December 12, 2023 6:30 PM

If it works well there, keep it there.  I hate taking up track where I never experience a derailment.  Also, if the bridge looks good in its setting, and the trains ALWAYS go across smoothly and cleanly, don't mess with perfection.  If you occasionally get derailments,, go for it.  You can make it perfect.

It takes an iron man to play with a toy iron horse. 

  • Member since
    September 2011
  • 6,434 posts
Posted by MidlandMike on Tuesday, December 12, 2023 9:03 PM

kasskaboose
... Also, are abutments needed for such a bridge or depends on a bridge's length?

Abutments are needed at the ends of the bridge to support its weight and load.  Also since a truss bridge is expensive to build and maintain, its length may be limited to the width of the infrastructure, river/floodplain or high valley it crosses.  Its approaches might be fill which is cheaper to build/maintain, so that a higher abutment will be needed to also hold back the fill.

  • Member since
    February 2008
  • 2,354 posts
Posted by kasskaboose on Wednesday, December 13, 2023 9:18 AM

Thanks all for the education and guidance.  I won't bother to relocate the bridge.  Why tear up operating track and "finished" scenery?

  • Member since
    September 2003
  • 21,606 posts
Posted by Overmod on Wednesday, December 13, 2023 9:29 AM

Added to that: you now have the chance to build a likely more 'prototypical' truss bridge installation.

Aside from better detail and proportions on the bridge structure itself, you can model the very tiny but important elements between the ends of the bridge truss and the load points on top of the abutments: the bridge 'shoes' or 'hinges'.  In the real thing, these allow the bridge to 'bow' slightly to accommodate thermal expansion, rather than needing to slide to change its length.  On a model of course the effect is likely minimal, but in my opinion at least it adds great 'realism' to see a model bridge built with the understanding of how a real-world one works.

  • Member since
    February 2008
  • 2,354 posts
Posted by kasskaboose on Thursday, December 14, 2023 5:58 PM

THanks @overmod for the additional insights.  Never knew about the slight bow for expansion.  While I agree few notice (or care) about this on a layout, still very interesting to pay some homage to reality.

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