Cedar is rot resistant but it will rot quickly submerged in water. It doesn't even do well with ground contact. If you really want to use a natural wood I would go with teak or mahogany (ipe, manzanita, and cypress are more options).
If I was building it, I would use cedar for the above water part and use a closed cell PVC wood for the below water sections. Tufboard is what you can find at most home depots and I think NeverRot is the lowes brand. It can be ripped down on a table saw, nailed and glued with pvc glue. Spray paint it to make it look more wood like.
-Brian
Tom Trigg
An option could be a stone pier with a trestle setting on top. Just get some flat cut stone and stack to the appropriate height to get the trestle above the water line then build the trestle bents to the height you need and glue or screw them to the stone. Very prototypical for rivers! Second option could be one of Garden Metal Models plastic piers with a stone support if needed to get it to the height you need.
Mark
I think there was a GRR article on TUffboard buildings. Using it for ties seems like a great idea. Perhaps submit it for a page in the magazine and show it replacing rotting ties for the back page mistakes. Just a thought.
I'm wondering about the artificial wood they use to make decks. If that too would work for ties or for the original part about wood in water. My thinking is that it lacks grain and would have to be distressed. Well, perhaps the outside has grain pattern but when you cut it up, only one side would have the pattern.
FJ and G wrote:I think there was a GRR article on TUffboard buildings. Using it for ties seems like a great idea. Perhaps submit it for a page in the magazine and show it replacing rotting ties for the back page mistakes. Just a thought.I'm wondering about the artificial wood they use to make decks. If that too would work for ties or for the original part about wood in water. My thinking is that it lacks grain and would have to be distressed. Well, perhaps the outside has grain pattern but when you cut it up, only one side would have the pattern.
I don't recall anyone using Tufboard for buildings but it is use a lot for ladder track systems. I don't think it would work well for ties either. I dont think small spikes would hold well in it. The company Swithcrafters uses a composite material for their ties but I am not sure what it is. There have been a number of issues with mold and mildew with composite decking materials when they stay constantly damp due to poor air circulation. Ground contact would only exaggerate that problem.
smokymtguy;
You don't mention what type of bridge you're looking to build. If it's a deck girder, you can build it using a pair of 2x4's laid on their side and you wouldn't need a center support. If you're building some other sort of bridge, say a Howe Truss, then you could lay the 2x4 flat as a spine and build up the bridge around it and you still wouldn't need a pier. Six feet is not a great distance unless you're gonna run something like a Big Boy over it. You may even want to consider steel L-girders as a spine.
However you do it, it'll be more dramatic if you don't use a center brace, and you won't need to worry about the fish.
If you have a couple bucks to spend, this should fit the bill:
http://www.eaglewingsironcraft.com/bridges.php
Have fun with your trains
Eaglewings Iron Craft products will most likely strain the budget, but, if properly painted and maintained, they will definitely out live us.
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