Build the bridge first or build the gorge first

Discussion in 'Scratchin' & Bashin'' started by Chaparral, Jan 12, 2008.

  1. Chaparral

    Chaparral Member

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    Which comes first, the bridge or the gorge the bridge will span?

    If I build a trestle bridge first I have excavate a gorge to fit.
    If I excavate a gorge, I have to cut and fit the bridge into it.

    So, what I was thinking is that if I were to make a template for the gorge I will excavated in the styro at the edge of the layout, I could use that same template to design and build the bridge! That way the bents should all fit and I can scenic the gorge without worrying about damage to the bridge-which will stay safe on the workbench??

    Any holes in that?
  2. Ralph

    Ralph Remember...it's for fun!

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    Sounds like a good plan to me!
    Ralph
  3. EngineerKyle

    EngineerKyle Member

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    Build the bridge to fix a rough opening... Then "plant " your bridge into the foam. This is easier still if you are putting it into a layer of wet scenery material like stucco patch.

    That's how I do it.
  4. doctorwayne

    doctorwayne Active Member

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    As long as you plan for the type of bridge that you intend to use, either way will work. Most of my bridges were built after the rough scenery was in place. I used patching plaster over screen for scenery, but created my own set of problems - not related to the scenery-making method. Most of my mainline track is on 3/4" plywood roadbed, and it was built continuously around the layout, even where bridges were eventually intended to go. I used the roadbed as a pattern for the bridges, as all of mine have some sort of a curve or curves in them. When I was ready to build and add-in a bridge, the corresponding roadbed was cut out with a jigsaw.
    For this bridge over the Maitland River, I built the bridge to follow the curves of the roadbed, then cast the piers and abutments in patching plaster. This bridge was the only one installed before the scenic plaster landforms were in place, so the piers and abutments could all sit on the flat plywood surface of the unfinished riverbed. The tops of them had to be cast to accept the various types of spans making-up the bridge, and after painting, they were glued in place with carpenter's glue. The finished bridge was then plopped into place. The bridge, all one piece, is removeable, so it was relatively easy to finish the scenery and "water" when I was ready.
    [​IMG]

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    [​IMG]

    This next bridge was a similar situation, except that the plaster landforms were already in place. The main difference in placing the bridge was that the bottoms of the cast abutments at either end had to be carved to fit the contours of the river banks.
    [​IMG]

    [​IMG]

    The three spans are, again, all one piece and removeable, so it was easy to go back later to add the trees and water.

    The lower bridge in the foreground was similar to the previous one in installation and is also removeable and one-piece. Both abutments and all but one of the piers had to have their bottom surface carved to suit the terrain.
    [​IMG]

    [​IMG]

    The high bridge in the background is also removeable and one-piece, but because of the support structure (i.e. not monolithic), posed some problems.
    [​IMG]

    Because the scenery was already roughed in, I cast footings of various heights to suit each leg of each tower, then had to carve the bottom of each to match the terrain. Each footing was drilled out to accept a short length of 1/16" music wire, which was ca'd in place, then each tower leg's base was drilled with a corresponding hole - this allows the bridge to be removeable and also keeps it properly aligned and stable. The large, cast abutments at either end of the span had to be carved to fit the high points and contours of the terrain, then more scenic plaster was applied and the abutments "squished" into place. Any excess plaster was cleaned-up before it set.
    [​IMG]

    The uppermost bridge, also one-piece and removeable, was similar to the one shown just previously, with the difference that the footings and abutments were made with .060" sheet styrene.
    [​IMG]

    The abutments were built with sheets, much as you would build a structure, then the bottom edges were carved to suit the terrain. After wetting the area slightly, more plaster was added to provide a soft base, then the abutments were pressed into place. More plaster was also placed inside the abutments, to give them greater strength and stability.
    [​IMG]

    The footings were made by stacking appropriately sized squares of .060" styrene, until the required height was achieved, then the top edges were bevelled and the bottom faces carved to match the terrain. They were first set in a bed of soft plaster, which was then worked up around each footing to hold it in place. All had a piece of music wire inserted, as with the previous bridge.
    [​IMG]

    All of the extra work for the last two bridges could have been avoided if I had planned out the bridges before doing the scenery. I then could have made a large, flat platform under the spot where each tower was to be located. This would've allowed all of the legs on each tower to be the same height, and all of the footings of all towers to be the same size. I could've also made suitable platforms to support the abutments at each end of the bridges, simplifying the casting process.
    So, if you plan ahead, you can do either scenery or bridges first. ;):-D:-D

    Wayne
  5. EngineerKyle

    EngineerKyle Member

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    I've seen those before Doc, but they are so good it thrills me to see them again like the first time!
  6. doctorwayne

    doctorwayne Active Member

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    Thanks, Kyle, it's always nice to know that people enjoy viewing it as much as I enjoy showing it. ;):-D

    Wayne
  7. dwight77

    dwight77 Member

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    doctorwayne: Great pictures of your bridges. How about some more pictures of your layout, from a bit further back, to see how all the bridges fit into your railroad. With all those great bridges, they have to have some great places to take the trains.
    dwight77
  8. doctorwayne

    doctorwayne Active Member

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    Thanks Dwight, here's a couple of links: the first one is self explanatory, while the second is a list of further links to all sorts of pictures taken on my layout.

    Layout (room) tour...

    A fresh update...

    Wayne
  9. dwight77

    dwight77 Member

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    Hi doctorwayne:
    Wonderful work. Now my envy factor is through the roof as return to my 5 1/2' x 10' N scale layout.
    But I do appreciate your sharing.
    dwight77
  10. Chaparral

    Chaparral Member

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    WOW !! repeat, WOW !!

    doctorwayne, the advice,the photos and that railroad, are absolutely fabulous.

    The links are sweeter than a knot hole in ball park fence!!

    Thank You, Thank You, Thank You, Thank You !!!


    I tried too hard to tall forehead this one.

    Attached Files:

  11. doctorwayne

    doctorwayne Active Member

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    Thanks guys, I hope that you found some of the material useful for your own endeavours, too. ;):-D:-D

    Wayne
  12. Doc Holliday

    Doc Holliday Member

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    Great work doctorwayne! You do truly inspiring work.

    Chaparral,
    I had the same problem when I started. To be truly protptypical, build the ground first and then custom build your bridge to fit, with some minimal "grading" work if needed.

    Having said that, I did the opposite for my trestles, building them first, hanging them in place and then filling in around the piles/bents with plaster.

    Show us some pics of how it turns out.
    Doc
  13. Gary Pfeil

    Gary Pfeil Active Member

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    Here is how I went about installing a trestle on my layout. This is way more modest than the bridges Doc Wayne built (those footings for the steel trestle on your upper level look like they were lots of fun!)

    First of all, I made the length of the "gully" to accomodate a Central Valley bridge which would be on the mainline. In front of that bridge would be an abondoned wood trestle, replaced with a girder bridge. I built the trestle and put in place on the flat riverbed as in the first photo.

    [​IMG]

    I then cut foam to fit between the bents of the trestle and put them in place, painting a basic earth color

    [​IMG]
  14. Gary Pfeil

    Gary Pfeil Active Member

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    I then spread my ground cover mix (sawdust, yellow glue, earth colored latex paint and water) over the foam to the contours I desired. I sprinkle sifted dirt and foam on this. The fact that I painted the foam earth colors prior to this was not necassary, I had only done it for an idea of appearance, the pink distracted me! Here you see I have added the mix behind the trestle. I used a small spackle knife to add the mix between the bents.

    [​IMG]

    Here's an overhead view with more mix added, and a bit of the replacement bridge in view.

    [​IMG]
  15. Gary Pfeil

    Gary Pfeil Active Member

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    Both the mainline truss bridge and the girder used for access to a small yard are removable, while the nature of the wood trestle made it a captive. This shot shows the truss in place while the girder is out, and shows the abutments for the girder, made of styrene.

    [​IMG]

    This is the only pic I have so far showing the 3 bridges. It doesn't show much of them however, and the river, not at all. I'll work on that.

    [​IMG]
  16. doctorwayne

    doctorwayne Active Member

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    Your water looks good, Gary, as do the trees in the background of the last shot. When you get around to some more pictures showing the bridges, maybe we could see a little more of that Berk, too? ;)

    Wayne