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Trestle Bents to supports

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  • Member since
    August, 2003
  • From: Canada
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Trestle Bents to supports
Posted by wickman on Tuesday, May 16, 2017 9:11 PM

Just completing a couple large curved trestles and was wondering what you's have used to sit the trestle bent footings to the scenery? I'm thinking of using 3/16 x3/16 basswood painted concrete colour attached to the bent base then to the scenery base.

 

You can see what I mean in the photo where the 3/16 square is under the bottom of one of the bents

 

and the second

 

  • Member since
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  • From: Central Vermont
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Posted by cowman on Tuesday, May 16, 2017 10:02 PM

Cut a chunk of your scrap foam.  You can make it any height you need and can taper it to look like many poured footings I have seen.

I have seen some very good looking piers done with it.

Good luck,

Richard

  • Member since
    February, 2005
  • From: Southwest US
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Posted by tomikawaTT on Wednesday, May 17, 2017 12:21 AM

Since your bents are built with dimensioned timbers they should sit on masonry (stone or concrete) footings.  If they were simply round peeled tree trunks they could have been pounded into the ground with a pile driver.

That said, there are about as many ways to model either stonework or poured-in-place concrete as there are people who have modeled trestle footings.

Wooden or cribwork footings would only be used under very temporary trestles, since rot would set in as soon as the timbers got wet.  By temporary trestle, I mean one which was thrown up 'quick and cheap' to get the rails across the low spot.  Dumping fill to convert the ROW into an embankment would have commenced almost immediately.  A good way to model this would be to have a bunch of dumped material (earth and rock) around the lower portion of the bents, with a culvert of some form in place to let the stream keep running.  The culvert would be long enough to still be clear when the new embankment reached its full height, and would serve to show how wide the base of the finished fill would be.  The prototype I have in mind is just east of Edgemont, SD.  There's a rather humongous fill which was built as a trestle, then served as a waste dump for all the cuts further along on the CB&Q route to Deadwood.  It's now a rather long hiking, biking and equestrian trail, easily traced on satellite view.

Chuck (Former Rapid City dweller modeling Central Japan in September, 1964)

  • Member since
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  • From: Vancouver Island, BC
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Posted by selector on Wednesday, May 17, 2017 12:41 AM

Trestle bents have posts in them, and as Chuck has said, if they are round they can/usually are pile-driven into the ground to get to hard-pan. These are post or pile frames.  For dimensional timbers, those squared in cross-section, they would rest on a 'mud sill'.  These are frame bents.

There's no mud connected with mud sills, but it's really a bed of treated timbers dug into the earth to form a base on which to support the weight of the trestle. Some parts of a trestle can be supported by concrete plinths, especially the frame bents nearest a central Howe Truss.

  • Member since
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  • From: Canada
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Posted by wickman on Wednesday, May 17, 2017 6:14 AM

Very good information guys. I like the idea with the scrap foam board. Any idea how big a concrete footing would be or at least one that can be seen thats been poured into a form for the framed bents to sit on would be? I'm thinking the 3/16 square may do the job by simply painting them , attaching too the underside of each framed bent and then mold the base for them upward using scaptamold.

  • Member since
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  • From: Vancouver Island, BC
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Posted by selector on Wednesday, May 17, 2017 11:00 AM

I see I called them plinths earlier, but they're pedestals.

This is a photo at the base of the central Howe Truss on the Kinsol Trestle in southern Vancouver Island.  As I said earlier, these only appear at the edge of the Koksilah River over which the trestle affords passage for trains.  They support the frames that support the ends of the Howe Truss which sits directly over the river.  All other foundations for this trestle are mud sills.

 

You would want carved foam pedestals that are tapered from about 9/16" square at the base and only 5/16" at the top platform to support the bottoms of the frames supporting the Howe Truss.  Or, whatever your design calls for. 

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Posted by SouthPenn on Wednesday, May 17, 2017 12:36 PM

Interesting.

When I went here, to look at trestles, it looks like the majority are in the ground.

South Penn
  • Member since
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  • From: Canada
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Posted by wickman on Wednesday, May 17, 2017 2:18 PM

This is some interesting facts, I wonder if I may be further ahead removing the base bent timbers and driving them into some mud/plaster down to the bed rock?

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Posted by 7j43k on Wednesday, May 17, 2017 3:54 PM

Looking at the slope of the ground under the trestle, I don't think there would be enough depth of dirt to use driven piles.

 

Ed

  • Member since
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  • From: Canada
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Posted by wickman on Wednesday, May 17, 2017 9:19 PM

7j43k

Looking at the slope of the ground under the trestle, I don't think there would be enough depth of dirt to use driven piles.

 

Ed

 

Will be if I drive them to the floorBig Smile

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