Plans for a small bridge?

[stravis]

I just bought some property with a small beaver pond on it. The pond was originally built with a man made dam, however some time ago the beavers dammed up the culvert and when the dam washed out, they built their own dam. So now I have half a man-made dam with a beaver dam in the middle. I don't mind and in fact kinda like it that way. Problem is, the man-made dam was the only easy way to access a field on the other side of the pond. I'd like to build a small bridge to span the beaver dam and connect the two remaining pieces of the man made dam. The span would be about 15 feet or so. Anyone know where I could get some plans to do this? I'd like to do the work myself, but it needs to be pretty sturdy as I'd want to be able to drive the tractor across it. The tractor is a Ford 3000, about 4000 pounds. Thanks in advance for any help.

 

[Duffster]

What do you think you want to make it out of, wood or steel?

 

[Airic]

Pictures?

 

[stravis]

I'd like to go with wood if it can handle the weight. I'll be back on the property either tonight or tomorrow and I'll take some pictures to post, however right now the area all around the beaver dam is grown over with small trees and bushes so it might not help much. I'm going to have to clean it up quite a bit before I can build the bridge.

To help visualize it, it is basically a straight dam made of dirt. The flat portion at the top is about 15 feet wide. The water on the one side is about 2 feet below the top of the dam and the ground on the other side is probably 5 feet below the top of the dam. About 15' of the middle of the dam washed out and the beavers built their dam across the washout. The top of the beaver dam is about 2' below the top of the man made dam.

I'd prefer not to arch the bridge itself unless necessary for strength.

 

[AndyMA]

3 light poles laid across decked with 2x6 PT laid at 90 degrees to the long spans.. If you place the poles just under 3 feet apart and ovrhang the 2x6x10's 1 foot on each side it will be plenty strong. Use southern yellow pine 2x6's

Andy

 

[scgargoyle]

Probably not strong enough for your needs, but these are pretty and interesting bridges: pacifi.ca. I built a 15'.

 

[AndyMA]

Probably not strong enough for your needs, but these are pretty and interesting bridges: pacifi.ca. I built a 15'.

Why do you think that the span is only 15 feet and the 4000 pounds is fairly widely districuted with most of it right over a pole. Think about the load a light pole takes both in absolute weight, wind load and the lateral pull of the wires.

Have you done the math?

Andy

 

[MarkV]

Well what I did was find 2 ramps from an old auto shop car lift to span a stream. They have no deflection that I can tell with a 7500 pound tractor on them. The pair I got were $200 from a private owner but maybe an add in the paper would turn up a pair.

MarkV

 

[deputyrpa]

How stable are the two earthen ends (where the man-made dam washed out) that you are going to span? You should also consider the potential of failure from saturation and the weight of the bridge and equipment. Dams are not designed (by humans anyway) to have water flowing through, or permeating an un-reinforced cut or weir.

 

[dawoodwa]

I have a friend that spanned a creek with an old flatbed trailer. He cut the running gear off and redecked it with treated lumber. We used a backhoe and some winches to get it across the creek. He used a 45 foot flatbed and we let about 10 feet overhand on both sides. It required some digging to get it down flush with the existing grade, trailer frame was about 12" channel.

If you use something like this capacity shouldn't be anything to worry about. I am planning on installing something similar to access the backside of my property. I have always used culvert pipe but the trailer was much easier to install.