Bridge plans

First question how much money you want to spend??O K Got your attention now excavate on both banks back and down about 4' square and build your forms and fit your rebar also weld the rebar together ,and you will need about 40 bolts 30" long and 2 " in diameter weld the bolts to the rebar and when the concrete has dried you have your footer It will need to be about 10' wide X 4' deed and thick. second in the middle of the stream you will need to dig down about 36" by 12' wide X4' and level this area ,then build a form to be level with the ones on the bank then rebar and bolts just like the edges ,you will need 8pcs. of 6" I beam 24' long theese will require being bolted to the concrete and thenyou need to build your decking,here you can go wood or concrete use 4" thick planks bolted to the I beams or lay plywood and then your rebar welded to the bolts you placedthen finish you framing for concrete cost may exceed $$8000.00 to build this this way or go cheap buy (2) 28' pup trailers and have a crane sit them on concrete pads place them side by side.this cost will be about $$3000.00 mostly for crane rental and concrete.

 

Welding rebar that is inbedded into concrete has been a construction No-No for at least 60 years. The weld will develope rust which will split the concrete, same as tree roots do. Rebar must only be wire tied, never welded.

 

Are you thinking metal I beams with a concrete footer on either side and 3x timbers across the beams? Can be fairly cheap if you can find good used I-beam locally.

All-wood construction requires pilings, massive cross beams. Unless you stumble upon an old salvage RR bridge or the like, going to cost a ton.

Don't weld rebar, & be careful of internet advise.

--->Paul

 

Comments

1) Advice on rebar is sound, though the issue is of metallurgical uncertainty, not rust. For example it is ok to have some tight rust on rebar as you use it normally in wire tie applications.

There are vendors that supply rebar that can be welded:

http://www.onesteel.com/images/db_images/productspecs/ONESTEEL Welding Guide.pdf

But What skills do you bring to bear on the project? Are you an accomplished MIG Welder? If not, don't try to learn on a bridge.

The big used steel I-beams and wood timbers approach is pretty practical. There is this need for a crane ..... and concrete work on the far side BEFORE the beams are set up.

There is a very neat bridge design model called West Point Bridge Design, free . Google it and learn about metal bridges.

There are several points you need to really, really need to have a handle on.
1) What is the maxium loading of the bridge. Fire trucks, oil/propane/lumber trucks etc? Learn about H20 loading.

2) That water way .... you may have a huge permit consideration building over a feeder in a watershed. The argument goes like this: WHAT IF during a big bad storm your bridge fell down and caused a buildup of water. which then released it self downriver .... dealing with this may affect your design not to mention your permitting costs. (though 15 feet IS kinda small)


good luck

owhn

 

Is a major size culvert out of the question? I have heard of some people useing a retired flat bed road trailer with the wheels removed. Since access is a problem I would suggest you check into a triangle metal roof system to mount wood up on. Some of those metal truses carry big weight.

 

I've seen oil people just pour concrete in the bottom and it took some very heavy loads but you would have to cut the banks down for access and its no good during high water. I've also seen logging bridges make with green logs that lasted a long time, you would need to cut the banks down enough to level it out, place a treated header for the timbers to sit on and it will last even longer, three logs for each track and you can cover with 2 X 10's or check with you county supervisor, I've picked up some good stuff that they were going to throw away.

 

This military manual looks to have a lot of information that is relevant to your question, like:

http://155.217.58.58/cgi-bin/atdl.dll/fm/3-34.343/toc.htm

DESIGN
Chapter 6 BRIDGE SUPERSTRUCTURES
Design Phases
Design Sequence

Chapter 7 SUBSTRUCTURE DESIGN
Abutment Design Procedure
Abutment Designs
Intermediate-Support Design

Chapter 10 CONSTRUCTION
Planning Process
Material Preparation, Timber Framing
Ch 12 Timber-Truss Bridges

Appendix C TIMBER PROPERTIES
Civilian-Design Stress
Military-Design Stress

A lot of military manuals, especially the engineer manuals, have a lot of good information for homesteaders.

 

"Simple, strong and the ability for full size vehicals to cross are required."

I would look at getting used utility poles from your local electic utility, we pay $3 apiece for used 30-35 foot utility poles, line up a couple of these across the creek for each set of wheels to fit on and a side guard on each side, plant a few horizontally with cement feet, and cable/bolt it all together, can't get much cheaper than that.

 

well i tell ya what i'ld do. i'ld find me a mobile home frame, very possibly for free if you can find 1 thats been in a fire, most are not hurt because it seldom burns through the floor and heat rises. get 1 about 60' long or so and cut in half lenght ways, then cut in half cross ways so you'll end up with 4 30' sections. lay them from 1 bank to the other with about 7' or 8' lap on both sides, weld cross pieces for support as needed and bolt down full 2x8 oak sawmill lumber. then build the road up on each side to get on the bridge. take a steel cable and fasten it to 1 side and then to a big tree so when the water gets up it'll just wash around to 1 bank and not down the creek. very cheap, very easy, and it'll carry anything you can put on a pickup.

 

As long as you realize you only own the land, the water belongs to someone else, it's just passing through your land. Mess up the water, & the neighbors, 'the man', & I will be ticked.

How deep is the creek? How full does it flow?

Wood rots. Generally when we assemble stuff cheaply & in a remote location we don't use the best materials. Old telephone poles, etc. - rot. You'll drop in in 10 years.

Metal is better. If you can get a flatbed or mobil home (these are not that strong, but you get some sort of a frame to strengthen) in there for the stringer value, or if the water flow is low several culverts - you will have a good foundation. You can find used culverts at highway & other utility places.

I'd hate to spend the time to make a 10 year project that wrecks my truck when it drops me in the water.

Just my opinion.

--->Paul

 

I would go with the telephone poles and a couple of layers f 2x10 for a deck.

mikell

 

This past weekend dh and I happened to cross a bridge over a deep(but not too wide) creek. It had apparently fallen on dissrepair, and had been repaired using big metal barrels filled with concrete as footers(under the remaining concrete from the original bridge). It also had I beams( I asume were original) and long hollow metal "poles" laying across the part you drive. Didn't look safe to me but it held the Ram just fine. We stopped to take a good look at it but didnt take a picture.

 

This is an interesting post. Thank you. I may need to do something like this in the future.

You only described the width of the bridge. How far from the top of the bridge to the bottom of the gulley?

I assume, based on your response that you are driving across now.

I think Moopups suggestion to put in a culvert and cover it with dirt is the best and cheapest idea.

You might find a good deal on these culverts at a big city metal salvage. If you make the culvert of ferrocement, you could carry the materials in your Urubus (backwards).

Some available new cement materials could form a thin shell over the dirt and make a good driving surface. I know they are using this for half inch thick driveways. I plan to do a deck this way in July. Even at one inch, you would only need about 1/3 cubic yard for the surface.

A two foot ferrocement culvert would bring the total cement to one half yard. Your total expense would be around $400-500. It wouldn't rot like wood. Termites wont eat it. Your truck wouldn't fall through. The water wont rust it. And you won't need a mortgage to finance it.

Good luck, Gary

 

Get some big logs and a tractor with a loader or hire a backhoe for a while.

Please see the sketch (not exactly a "downtown" AutoCAD drawing - more like a homestead plan), this would only work in a very remote area, like where our farm is located - not too many people bother us. And we have lots of logs, too many, lots of big logs are burned to get them out of the way for farming. And no one is going to sue anyone like in other places. And if it rots out or falls down or washes away I would just build another one.



You can do it, you can sure make it blend-in and "natural".

Good luck, fun project(s)

Alex

 

The last crossing will be our view from the living room. So this bridge needs to "blend in" with the surroundings - so I would like to stay away from drums, culverts, concrete etc.

punkrockpilot- Don't know how good a stone mason you are, but if you went with a native local stone facia, it probably wouldn't look to out of place. A culvert with a flow adjuster could give you a swiming pond right there in view of your front room. You might be able to get a nice water fall effect from the overflow. Heck, you might even be able to get hydroelectric out of the thing.

There you go pard- you got the bridge, the swiming pond, the waterfall, the electric company, all right there outside your front room window.

Would a diving board look to far out of place ?

 

I wonder what the surplus market is like for an old bridge laying tank?

 

Check out pacifi.ca - very nice and elegant bridge design