I know I've had a couple other discussions about a trestle but I thought I may as well start a new one to see how you's deal with the trestle bent base gap to the risers. I'm thinking I have 3 possible options 1 folder over plaster cloth and sit the trestle in place to fit for each bent, 2 do the same with plaster of paris and 3 use goop testing the same way for seating. As you can see the trestle is levelled proper so cars don't weight to the outside going around the curve. You can see in the photo the gaps under the bents. I guess I left a bit too much room for error. Your thoughts guys?
Lynn
Present Layout progress
http://cs.trains.com/mrr/f/11/p/290127/3372174.aspx#3372174
Gaps are no big deal. Fill them with rocks/dirt/sand. Google some prototype photos if you don't have some handy and proceed from there.
I intentionally left gaps under all the piers on this steel trestle so I could get the whole thing in and out of the scene while working on plaster and so on. They were intended from the start to be filled with the final ground cover.
More of the same around this wood trestle. Note the concrete footings, which were commonly used to prevent rot from the bents sitting directly on the ground. Sometimes stone was used for the same purpose. I made the footings from stripwood, and attached to the bents prior to installing the trestle. I shimmed it into place and then filled under the bents with sand and small rocks.
One thing to consider with your installation is the height of vertical slopes between the bents. Those are begging for retaining walls using cribbing, stone or concrete.
Rob Spangler
If it's a relatively "new" trestle, i.e. 19th or early 20th century, and the ground is not soft, sometimes timber cribbing formed the footing. The wooden footer of the bent itself would rest on large beams to spread the weight of the trestle out.
If the footing slopes, you can often cut a long thin wedge for the footing timber, slide it under until even contact is made, then trim the excee that sticks out from under the footer on each end.
Mike Lehman
Urbana, IL
Already got some good ideas, maybe for the final installation, however, I notice some quite large gaps and some bents rather close to the "step" edge. Those areas should be built up w/ plaster first. To not make a real mess of the bent base, mask or plastic wrap them. Small margin trowels and pallet knives will help place the plaster. I would use Hydrocal for this. Work in small batches so you don't feel rushed working on each of all those numerous bents. The platic wrap may work better than masking tape as the plater won't stick making any removal much easier. You will see the footprint of each one, so as you scenic any behind and under you can stay away from the base to replace.
BTW, I must commend you on some excellent work on that piece.
Modeling B&O- Chessie Bob K. www.ssmrc.org
Trestle Bent Gap?
Lynn, It took a couple times reading over your initial post here to determine what you were talking about. This must be my inability to understand the written word, as others got what you were talking about right away!
As your trestle sits right now, I'm sure the structure can withstand all the weight it needs to, to support your trains. So you’re simply talking about the gap between the bottom of the bent and the hard shell beneath. I would simply put small shims underneath, being careful you don’t jack the bents up, the shims need to just meet the bottom of the bents. Then fill in with your scenery when you’re ready to permanently mount the trestle.
By the way your trestle is outstanding! Great job!
NP 2626 "Northern Pacific, really terrific"
Northern Pacific Railway Historical Association: http://www.nprha.org/
Thanks guys for the tips.
As i looked over the scene again, I wonder just what your base scenic form for the area. Is this to be a somewhat natural river cut ravine, w/ exposed river cut rock faces in igneous rock or does your prototype lend more to sedimentary soils/ rock. This would make a huge difference as to the approach to how you deal w/ the cut, terraced sides. That river bottom and base bents should be rock casting to show actual cut, the other tiers/ cut steps can show man made rock cut or jus a significant rock outcropping. If the scene is to be mainly covered w/ vegatation, random castings showing outcropping would be the easiest to accomplish by hiding quite a bit w/ scenery material, small trees, bushes and underbrush. If the area is more barren, you will have to show the base and make any of the sedimentary rock more believable, lots of work for a large area.
Shim it and fill in the area with Patch-all.
bogp40 As i looked over the scene again, I wonder just what your base scenic form for the area. Is this to be a somewhat natural river cut ravine, w/ exposed river cut rock faces in igneous rock or does your prototype lend more to sedimentary soils/ rock. This would make a huge difference as to the approach to how you deal w/ the cut, terraced sides. That river bottom and base bents should be rock casting to show actual cut, the other tiers/ cut steps can show man made rock cut or jus a significant rock outcropping. If the scene is to be mainly covered w/ vegatation, random castings showing outcropping would be the easiest to accomplish by hiding quite a bit w/ scenery material, small trees, bushes and underbrush. If the area is more barren, you will have to show the base and make any of the sedimentary rock more believable, lots of work for a large area.
Thanks Bob for the interest, it is much appreciated. Question though, why is it everytime I converse with you I feel the need to get out the dictionary LOL, I really gotta work on getting into the lingual. So to answer the question to the best of my thinking I would have to say I model more toward the lush side but also with many rock faces popping out. You may have to take a peek at my layout thread to get what I mean. Hope this helps.
Always always apreciating suggestions.
Thanks
rrebell Shim it and fill in the area with Patch-all.
I agree as it is actually quite solid just sitting with the two ends seated.
I really don't want to be a party-pooper. The trestle itself is excellent work, and I wish I could do as well. However, I question the terrain under the trestle. It appears that the engineers/constructors carved shelves in the earth to support where the bents sit. I looked on-line and came up with a site that shows many different trestle installations and it appears that the bents were sort of planted in the terrain without much special consideration as to where they would sit. Take a look here: https://www.google.com/search?q=wooden+railroad+trestles&rlz=1T4GGHP_enUS443US443&tbm=isch&tbo=u&source=univ&sa=X&ei=ocqZVKjKAsergwTvnYHQDA&ved=0CDQQsAQ&biw=1157&bih=654.
Maybe you might want to revise the step effect a little. (or not)
I think the bushes/trees mentioned above would solve the problem of hiding the gaps and also soften the stair step effect in the hardshell.
I'd also consider some sway braces between the bents for a trestle that size and on a curve.
I have the right to remain silent. By posting here I have given up that right and accept that anything I say can and will be used as evidence to critique me.
Thanks guys , great suggestions. There definately with be bushes and lots of groundfall in the trestle area. I also plan on taking the 90 degree slopes from under the bents. I will also be adding sway braces. I'm presently applying a coat of tuf coat to the area in preparation for rock castings.
Framed bents like the ones you have usually sit on concrete footings.
the 'too vertical' steps can be sloped by adding material. Have rock showing, or put in cribbing, to prevent landslips after the next hard rain.
Very nice trestle. Of course, the prototype roads would immediately set about converting it to a fill. Concrete arch or box culvert at the bottom and some dumped material (dumped from side-dump cars on the trestle itself) at the culvert or along the entire length.
There's a nice example of a moderately huge fill that was once a high trestle about four miles east northeast of Edgemont, SD. Used to be the CB&Q line to Deadwood. Now it's a bike trail. Mapquest still shows it as a railroad decades after the steel was lifted.
Chuck (Ex-SD resident modeling Central Japan in September, 1964)
Timber trestles were footed on two types of 'sills'. They were concrete sills or 'mud sills'. Despite the name in the latter case, they were actually timbers, creosoted, and embedded into the earth after it had been scraped, if possible, to render it flat...ish. The pylons/posts comprising the bents' main uprights would sit atop the mud sill timbers. In some cases, the timbers were actually driven into the earth if the soil was not suitable for supporting a sill that could in turn support the bridge.
Note that the sills were kept clear of debris to a reasonable standard so that the wetness seasonally didn't accelerate their deterioration. They were not covered in mud, for example, nor were the locations on which the trestles were erected left in such a state that mud might eventually cover up the mud sills. Coarse gravel, ballast, small riprap, and some timber retaining walls were often used to prevent the footings from shifting or being undermined by flowing water or mud slides. In my experience, not that it goes back donkey's years, getting around and under most trestles is a bit of a grind and can be dangerous due to the condition of the land. After all, apart from actually filling in the gap, which was often seriously contemplated or even done, with soil and rock, the terrain was a considerable obstacle there, something which only a bridge or extensive fill could serve as a solution to maintain grade.
wickman bogp40 As i looked over the scene again, I wonder just what your base scenic form for the area. Is this to be a somewhat natural river cut ravine, w/ exposed river cut rock faces in igneous rock or does your prototype lend more to sedimentary soils/ rock. This would make a huge difference as to the approach to how you deal w/ the cut, terraced sides. That river bottom and base bents should be rock casting to show actual cut, the other tiers/ cut steps can show man made rock cut or jus a significant rock outcropping. If the scene is to be mainly covered w/ vegatation, random castings showing outcropping would be the easiest to accomplish by hiding quite a bit w/ scenery material, small trees, bushes and underbrush. If the area is more barren, you will have to show the base and make any of the sedimentary rock more believable, lots of work for a large area. Thanks Bob for the interest, it is much appreciated. Question though, why is it everytime I converse with you I feel the need to get out the dictionary LOL, I really gotta work on getting into the lingual. So to answer the question to the best of my thinking I would have to say I model more toward the lush side but also with many rock faces popping out. You may have to take a peek at my layout thread to get what I mean. Hope this helps. Always always apreciating suggestions. Thanks
Sorry, I don't catch myself most times, I'm not a geologist by profession, but have studied and reseached much of the geography of North America, almost a hobby of mine, long before working layout scenery. I deal in such precision on a regular basis in my daily work it tends to just spill over. I'll try to keep the explainations a bit more easier to decipher.
Great looking trestle Lynn
"The true sign of intelligence is not knowledge but imagination."-Albert Einstein
http://gearedsteam.blogspot.com/
Not a problem Bob
Geared Steam Great looking trestle Lynn
Thankyou
I hate to tell you this (I really do), but if that was a prototype trestle, it would collapse with the passing of the first train, as there is no support under the bent in the center. The longitudinal braces should be replaced by heavier girder beams, or maybe some diagonals .
Dave
Just be glad you don't have to press "2" for English.
http://www.youtube.com/watch?v=zQ_ALEdDUB8
http://www.youtube.com/watch?v=6hqFS1GZL4s
http://s73.photobucket.com/user/steemtrayn/media/MovingcoalontheDCM.mp4.html?sort=3&o=27
steemtraynI hate to tell you this (I really do), but if that was a prototype trestle, it would collapse with the passing of the first train, as there is no support under the bent in the center.
Ummm, the question of support under the bent bases and how to correct that problem was the reason for the original posting. Guess we need to start reading from the beginning.
No bigdeal with specifics with the trestle I'm not so much into protype anyway.