Building a Bridge suggestions?

[paintman161]

Okay so I want to build another bridge on my property, Last summer I re-did the old RR bridge and it turned out very nice! This year i was thinking of adding another bridge to cross another creek on my property. The problem with this one is I am starting from scratch. The creek width is about 40', but one issue is during the spring it likes to flood and the nearest banks that are high enough are about 150'-0" apart. I want to try doing this with wood (steel is too expensive). I have a lot of Ash on my property so i was thinking of maybe utilizing those trees?? I don't want anything in the center of the creek for supports since this is where the main water flows and gets going really fast during spring/ thaw. So that clear span would need to be 40'-0, the rest can be what ever. As for the width, maybe 4' or 5' just enough for an ATV to get across.

Picture shows looking up stream, you can kind of see the other bank which is higher in the background.


Any ideas on how to go about this?

 

[JoeL4330]

Index A versatile and scaleable bridge design for spans up to 50 feet, build foot bridges, design construction of foot bridges, constructing footbridge design, free bridge design, gartenbrücke, how to build wooden bridge beams, instructions for woode

http://www.fpl.fs.fed.us/documnts/misc/em7700_8_chapter02.pdf

Bridge Basics - A Spotter's Guide to Bridge Design

 

[paintman161]

Thanks for the information! It's a start.

 

[rd_macgregor]

Buy a 40' shipping container and torch the superstructure off for scrap (or, maybe you'll get lucky and find a flat deck or flat rack container, and not have to deal with sides and top). I think these containers have nearly a 20T capacity. Support/abutments is the next issue. My preferred would be a couple of steel piles on each side with a steel beam across the top. My second thought was burying Jersey barriers on each side as abutments...but I have well-defined banks where I want my bridge, so this might not work for you.
Your ash trees might work, but steel and/or concrete would outlast them, I bet.

 

[paintman161]

Buy a 40' shipping container and torch the superstructure off for scrap (or, maybe you'll get lucky and find a flat deck or flat rack container, and not have to deal with sides and top). I think these containers have nearly a 20T capacity. Support/abutments is the next issue. My preferred would be a couple of steel piles on each side with a steel beam across the top. My second thought was burying Jersey barriers on each side as abutments...but I have well-defined banks where I want my bridge, so this might not work for you.
Your ash trees might work, but steel and/or concrete would outlast them, I bet.

although a great idea, not very practical for me, wont be able to get a shipping container across, plus finding one around here is impossible. Also i have no welding or cutting capabilities.

 

[paintman161]

I was thinking about buying some Larch trees like 10" dia and sink them into the ground 36-48" (pilings) and use 2x10 rough cut for the beams across the top of the pilings. Then get some 50' trees and lay them across for my main beams and use 2x on top for decking. I was thinking only spacing them like 3'-6" or whatever the width of the ATV tires are.

 

[LD1]

Using your own trees without a way to treat them is a recipe for disaster in the near future.

And while cutting up a shipping container "may" work for your light loads, I wouldnt advise it as alot of the strength of them come from the sides and top. Picture a A box beam (or box tubing). Once the sides and top are cut out and you are just left with a flat piece of steel, it isnt very strong.

For a 40' clear span, I think you need to look at some sizable steel beams.

 

[paintman161]

Using your own trees without a way to treat them is a recipe for disaster in the near future.

And while cutting up a shipping container "may" work for your light loads, I wouldnt advise it as alot of the strength of them come from the sides and top. Picture a A box beam (or box tubing). Once the sides and top are cut out and you are just left with a flat piece of steel, it isnt very strong.

For a 40' clear span, I think you need to look at some sizable steel beams.

Maybe i will just make a suspension bridge for foot traffic only.

 

[davrow]

Maybe i will just make a suspension bridge for foot traffic only.

Foot traffic only? Then you can put in a zip line each way! :laughing:

 

[Oldtractorfixer]

We bought a used flat bed semi trailer. 45' X 8'. Guy we bought it from delivered it and kept the axles. Pulled it across with a winch on our D4. All steel and aluminum as on the highway caarries 40k. Added a hand rail and were done.