Need to build a small bridge

[dgl]

I need to build a small bridge across a creek using dimensional PT lumber. The bridge needs to support a 2,000 lb. tractor (JD 2210). The width of the tractor is about 48" (not counting the 62" belly mower). The total length of bridge will be 12' with a 7' - 8' span, and 2' +/- on the ground on each side of the creek. Would 3 6x6's as beams and 2x6's as planks be adequate?

 

[gordon21]

Can you get 4x12 instead of 6x6 for the beams? The extra height would mean extra strength. If not, you can make your own 4x12 by gluing and bolting three 2x12 together. That would probably be cheaper anyway.

 

[Coyote]

I used railroad ties as beams and landscape timbers for planks. It is similar to your size. If RR ties are too short, I would go with 8X8 for beams. It supports my tractor, my old jeep, and all the horses on the trail rides!

 

[Slacker]

RR ties work well if the span isn't too great. Also think about telephone poles. Use a chain saw to make some notches and quickcrete the ends into the ground. 6x6 would be my last choice, and I'd use 5 of them. Two one each side and one in the middle. Covered by PT 2x8.

 

[NCDeere]

Could you just get a culvert and put some dirt over the top of it? You don't need a whole piece so you could look around for a piece of scrap from some other job.

It's just an idea.

Bryan

 

[Timber]

I agree with slacker especially if your gona run a loader over it even a compact. Your gona want to be well across the banks. If your too close to the edge the integrity of the bank will fail in a short time depending on how often you use it. Telephone poles are great and obtainable but very heavy. The further across your banks the better off you'll be. I would also use footings under each end set below the surface and you can recess the poles below the surface to make your transition smoother. Hate to dump a load trying to board the bridge. You want good foundation materials because you don't want to worry about replacing your span as time goes. replacing decking is 1 thing but the span you only want to do once. I personally don't like cement aprons in a natural setting but that is personal. The other thing is be sure to bolt either a beam or even a pole on the surface of your bridge as a guard rail to keep your tractor on the bridge. Don't ever think you couldn't slip off. it will probably kill you. the river bed is soft and with water plus the drop off you wouldn't have a chance

 

[CurlyDave]

I agree with the culvert idea.

Unless you know how to do the engineering calculations for a bridge, you can get into trouble a lot faster than many think.

By the time you price out all of the pieces for wood, you will be very close to the cost of a culvert. If you have enough cover over the culvert, it is plenty strong enough.

 

[Bill Barrett]

Culvert idea is a good one BUT around the midwest if you put a culvert in and hold water back you are responsible for any damage. Also if in the flood plane you need Army Corp of Engineers approval. I'm doing this now and it's no picnic. It’s not like the good old days. I started working on removing one that was already in place to make it larger and had people miles away down my neck. If the bridge is out of the water way there is no issue. At least thats what I ran into. By the way this is all well in my property lines.

 

[ovrszd]

I need to build a small bridge across a creek using dimensional PT lumber. The bridge needs to support a 2,000 lb. tractor (JD 2210). The width of the tractor is about 48" (not counting the 62" belly mower). The total length of bridge will be 12' with a 7' - 8' span, and 2' +/- on the ground on each side of the creek. Would 3 6x6's as beams and 2x6's as planks be adequate?

A friend of mine spanned a 25ft wide, 8ft deep gorge with a bridge. he used a 40ft flatbed semi trailer minus the running gear. Your smaller creek could be spanned with a 14 or 16ft flatbed off a straight truck real easy. They are bull strong and if you get lucky and find an old one with steel flooring, you'll never have to repair it. I'm sure you can buy an old flatbed way cheaper than building a bridge out of lumber. My friend dug his into the ground so it's level with the trail grade. Very quaint, out in the middle of a huge timber.

 

[Bill Barrett]

A friend of mine spanned a 25ft wide, 8ft deep gorge with a bridge. he used a 40ft flatbed semi trailer minus the running gear. Your smaller creek could be spanned with a 14 or 16ft flatbed off a straight truck real easy. They are bull strong and if you get lucky and find an old one with steel flooring, you'll never have to repair it. I'm sure you can buy an old flatbed way cheaper than building a bridge out of lumber. My friend dug his into the ground so it's level with the trail grade. Very quaint, out in the middle of a huge timber.

This was one of my options, suggested by road commissioner .