Building a bridge

[pineywoods]

My son has a hunting preserve in central Mississippi. There's a spring fed creek across the property. Two culverts (one 36 inch, one 24 inch) and 5 truck loads of fill made a road across the creek. After the first summer thunderstorm it looked like this



We have plenty of trees and a woodmizer, why not build a bridge

here's the first step. There's 6 pilings on each side, 6X6 pt pine set in 7 ft deep holes and concreted in. The main supports are bolted to the pilings with 3/4 inch threaded rod



This pile of broken concrete then used to line the banks of the creek





Stringers are 6X12 pt pine 16 ft long, cut on my woodmizer



Decking is a full 2 inch pine
Yeah these gals swing a mean hammer ;D


The finished project



I sorta cheated and left the engineering to my engineer son, but I think he cheated and used Don P's calculator. We figure it's good for 30,000 pounds, heaviest thing we'll run over it is a 6000 pound mini-dozer

More to come....next is a cover, making a genuine covered bridge

[TexasTimbers]

That's cool. Makes me want to divert the creek onto my property so I can build one of those too.

Good job it looks great.

[submarinesailor]

Looks great.  Wish mine was going to be that easy.  If I'm lucky, it will need to be about 65 feet long, 75 if I'm not, and that's with no pilings in the river - not allowed by the Corp of Engineers.

[GF]

That looks great, thanks for the pic's.

[mike_van]

Nice job Pineywoods - Did you put anything on the wood for rot?

[Qweaver]

That's looking very good.  I have to do almost the same thing.  Thanks for the ideas.
Quinton

[pineywoods]

Nice job Pineywoods - Did you put anything on the wood for rot?

I found a place that had a pressure vessel big enough to hold all the wood. They pulled a vacuum on it for 2 days, then filled it with preservative and pressurized for 2 more days. If that's not enough, working on plans to build a shed over the whole thing.. DanG mississippi thunderstorms can dump a lot of water in a short period of time ;D

[thecfarm]

That looks good.Real good.Looking forward to the covered pictures.

[Don P]

Ummm, glad he found the calc useful, but I've never put up the bridge formula that I can recall  ;). Roughly from memory it halves the allowable load from the static gravity load beam calcs I've posted due to the dynamic loading of a moving vehicle. Don't slam on the brakes with a load  .

[pineywoods]

That's looking very good.  I have to do almost the same thing.  Thanks for the ideas.
Quinton

Quinton, one piece of advice on the support pilings. sink them as deep in the ground as you can. I made a 4 ft extension to go on a pto powered post hole auger. Should be able to drill down 8 ft. Just do it 2 ft at a time pulling the auger out and clean it. Otherwise the auger will jamm in the hole and it ain't no fun getting it out ;D

[PineNut]

I had an auger pull itself down in the ground. Fortunately it came out fairly easy. Turn it one way and it goes down. Turn it the other way and it comes out. A large wrench on the PTO shaft turned it in reverse and it came right out. Of course it was a number of turns but much better than digging. But still better is not letting it dig down in the first place.

[woodman]

   with all that work put into it , why don't you put a cover on it . Up here in snow country we make coverd bridges for a place to go if we get a rain or snow storm.
        o and thay look good to. ;D ;)

[Don P]

Woodman's covered bridge idea got my wheels turning. If you were to incorporate a well dimensioned kingpost truss into the sidewalls it effectively cuts the span in half. A queenpost truss would cut the beam spans into thirds. Same as dropping piers into the riverbed.  I think its fine for the loads you're describing, just more grist for the bridgebuilding mill  .

[Radar67]

I made a 4 ft extension to go on a pto powered post hole auger. Should be able to drill down 8 ft. Just do it 2 ft at a time pulling the auger out and clean it. Otherwise the auger will jamm in the hole and it ain't no fun getting it out ;D

Pineywoods, can you detail how you built the extension for the auger? Pictures maybe? Did y'all ever get the cover built for the bridge?

[pineywoods]

[quote author=Radar67 link=topic=27763.msg490903#msg490903 date=122629309

Pineywoods, can you detail how you built the extension for the auger? Pictures maybe? Did y'all ever get the cover built for the bridge?
[/quote]

I actually made 8 of them and used them to drill a water well. Only needed 1 to drill the holes for the bridge piers...

   a 4 ft piece of 2 inch pipe   




one end looks like this



Thats a short piece of 1 1/2 inch pipe welded in the end

and the other like this





That loop welded on the top end is used to stick a piece of rod thru to keep the whole works from falling back in the hole when you pull the pin (bolt) out.

[Radar67]

What grade bolt did you use for pins?

[pineywoods]

What grade bolt did you use for pins?

Hardware store stuff ;D

[WH_Conley]

After looking at those pics I had to take a little bit to get my nerve back. Reminds me of low overhead auger cast. If you are gonna get foundaions that way you are gonna work for it. It will work, very well, I just don't want to come and visit :D.

[Woodchuck53]

Submarinesailor, just a thought on your bridge. We had a stream to cover on a freinds lease. We poured concrete bulkheads 60' apart and set 2 48" I-beams that he found at a demolishing company yard. We drugged them across and set them 7' apart. I believe the flange was 10"x 1" thick. We then ran a light beam centered in the middle because some of his older tractors have tricycle front ends. Decked it with 3" treated material and load tested with a full load of concrete. About 80,000 lbs. in our area. Dug a pond for the dirt and built both approches, 8' tall and dress-sloped as needed also 1800' of road bed. Not sure of the total cost but a swell home place behind the pond looking down towards the bridge. All in 7 days. the bottem of the beam is about 6' off the water. Take care. Chuck

[woodmills1]

tested it with a load of concrete??

[Woodchuck53]

Nah, had plenty of large stuff over it. No deflection to speak of so they ran the slab loads for the house over it also. No problems. I stood by and watched though.