Boy Scout Manual.

Unlike a catenary, where the weight is evenly distributed along the arc, here the weight is distributed horizontally; this result in parabolic cables.

If all three cables sag in the middle, there will lots of bounce and sway. The triangular idea is right, but I think the upper cables should be low in the middle, with the lower cable high in the middle. This will give better stability.

But then upper cables will vary in distance from the lower, making them doubtful as hand lines. This can be solved by auxiliary hand lines at constant distance from the foot cable. These five lines can all be tensioned from guyed M-shaped frames at each end, with trangular lacing to suit.

Anybody who falls off = "floating Wallenda."

How to Make a Rope Bridge

Contributor By Brian Adler, eHow Contributing Writer Article Rating: (18 Ratings)

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I want to do this! What's This?

A rope bridge is a primitive suspension bridge. Used since the days of the Incas, they are still seen in out-of-the-way places. Made of wood and ropes, they can be built quickly over rivers or canyons. A favorite of extreme sports enthusiasts, they can be constructed in any suitable location.

Difficulty: Moderate Instructions Things You'll Need:

• Rope
• Planks

1. Step 1 Find a suitable space to cross. This means scouting out an area that is high enough on either side to support the ends of the bridge. The rope bridge works like any other suspension bridge. A pair of supports at either end secures a roadway that hangs down in between. The roadway must not sag all the way down to the bottom of whatever space is being crossed. The outermost supports must be able to pull the ropes taut.
2. Step 2 Support your rope bridge with sturdy supports like a tree or boulder at either end. You can also make supports by driving stout stakes or poles into the ground. Begin at one end of your planned rope bridge. Take a length of heavy rope and tie it to each of the supports. Make sure the ropes are stronger enough to hold a roadway of planks. Make sure these ropes can be the additional weight of people and goods crossing the bridge.
3. Step 3 Find a way to get your two main ropes over to the other side of the crossing. You can make a lasso and throw them across. Just make sure they catch on something. You will need to cross over the rope hand-over-hand. Go over to the other side. Secure each of the main ropes to the main supports on that side. Check to make sure all the ropes are firmly in place before beginning to lay the roadway of your rope bridge.
4. Step 4 Prepare enough planks to cover the length of your roadway. The roadway does not need to be completely covered in planks. You need just enough to be able to step from one to another without falling through. Bore a hole through each of the narrow ends of each plank. Take the first plank and a short length of rope. Tie the rope from one main rope through one of the holes in the plank. Do the same with the other plank hole and the other main rope. Repeat until you have laid all the planks. You can now cross over the roadway of your rope bridge.
5. Step 5 Make your rope bridge a little safer by adding handrails. Take two long pieces of rope. These should be about the same length as your main ropes. Tie each end of the rope to one of the supports. Make sure to place it a few feet higher than the main ropes. Run each of these ropes across the bridge to the other side. Attach the other ends to the supports on this side. For even more security, tie small lengths of rope from the handrail rope through the plank holes. You do not need to do this to every plank. Just do it on each side of every few planks. These extra ropes will serve to "hold in" the people who cross the bridge. They will also make the roadway more stable.

there was a bridge thread here before.. and my post in it. (re rail cars)

Last season, Mythbusters made a foot bridge, 100 ft long, out of duck tape. You might want to Google that segment for information about this type of bridge. (Note: Don't make yours out of duck tape.)

The next person who says (types/posts) "duck tape" is going to get wrapped, head-to-toe, in DUCT TAPE.

Watch Mythbusters. The original name was Duck Tape.

Duck Tape, Duck Tape, Duck Tape, Duck Tape, Duck Tape!

ya NO.. it is duct tape.. originally invented to seal metal duct work.. and then later on manufactured as the brand "duck tape"... which is also a completely inferior product as compared to the original, if you ask me. When I was a kid, duct tape could lift your car...

Perhaps this link will help set a few things straight. Duct Tape History - Invention of Duct Tape Fascinating facts about the invention of Duct Tape by Johnson & Johnson Co. in 1942.www.ideafinder.com/history/inventions/ducttape.htm - Cached

I reiterate Duck Tape, Duck Tape, Duck Tape, Duck Tape, Duck Tape!!!!!

http://www.google.co.uk/products?hl=en&q=duck+tape&safe=active&um=1&ie=UTF-8&ei=l4BATJPuJcH34Aa1xMTFDg&sa=X&oi=product_result_group&ct=title&resnum=3&ved=0CEIQrQQwAg

Let's just call it gaffer tape shall we (or is it gaffa?).

The second sentence clearly identifies it as Duct Tape, before moving on to decribe it as duck tape.. but I give you a few points... 50%. but I think we should agree to to meet half way. I've been calling it Duct tape all my life, and I'm sure a few million others.. so I don't think it will change. It's not my fault. It is however, reality. I accept some of your position, but can not go all the way. sorry. That makes it purely 'preference'.

okay.. now we have done with this... I do not wish to discuss it any more. thank you. cheers,

Chris

As I Myself typically refer to it by it's current name (Duct Tape). I simply was feeling a little rebellious at the moment. Thank you for ceding the 50% on a completely ridiculous and trivial topic.

I'm still waiting to see if some one comes by to wrap me in the stuff.

GA...and be used at -20°F effectively...

DUCT - no quacks involved!

You can do this with a simple truss design. You will need to construct two of them and add a ledger to the inside of the bottom of each truss. This will provide you with a place to anchor the walk way. Flat top trusses are used regularly in the building industry, are simple to construct on site and even in place with just a general knowledge of carpentry.

If you cannot do this then I suggest that you have him check out some local steel building salvage companies. Bar joists salvaged from demolished buildings are quite reasonable. Are adequate for what your/his needs seem to be. For a foundation, he could use a couple of concrete parking bumpers. Keep the steel painted, and it should be a safe structure for quite a long time, wjth one hell of a lot less liability.

Anchoring cables can be a serious problem, as one only needs one anchor to fail and the whole structure fails, folks get hurt and call Lawyers and you know how the system works, "No good goes unpunished."

Good luck!

TMF

Design and Construction of Suspension Foot Bridges from ASSIST, EMP/INVEST ILO

http://www.ilo.org/public/english/employment/recon/eiip/download/bulletin/bulletin12.pdf

Lots of the kids soft play areas over here have this sort of bridge. It might be worth going to have a look at a couple of local ones. You're right about the three ropes; you also need strong netting tied from the top two, and under the third rope: this stabilises the three ropes relative to each other.

Don't worry about the catenary (suspension bridge) shape. That is only relevant when the weight of the bridge material is heavy compared to the weight of the moving load.

Have you got somewhere to anchor the ends?

Please make sure it's safe. Good luck.

Since you are in the New Hampshire area, check out the snowmobile suspension bridge in Hillsboro, NH. It crosses the Contoocock River, and can be found by heading to Morse's Sporting Goods from the town of Hillsboro. After you cross the bridge over the Contoocook, take your first right and go all the way to the end of the road. You should be able to see it by that point. It might be a little over kill for what you want, but scale it down a little. It looks more like a foot bridge than a snowmobile bridge. And no, we can't get the big groomers over it. In case you are a snowmobiler, this is the trail that heads to Livingston's Arctic Cat. If you can't find it, they will probally show you where it is.

Thanks for the input. The bridge I'm working on is at http://www.moosilauke.com/ If I can come up with a safe/inexpensive solution your more than welcome to come by and check it out. I'm having issues with anchoring points though, I do like the salvaged steel beam Idea someone else came up with. Just don't try to drive across it with a snowmobile : )

Hi Topper,

I would like to suggest that I have just the plan for footbridge...........but, on second thoughts maybe not.

I had another idea, but, that didn't work out very well either

Oh well you could always use a flying fox or maybe some strong vines!!!!!

I think I see a tripping point on the first bridge and the second bridge is defiantly to expensive. Thanks for the input.

In the words of Ralf Nader Unsafe at any Speed.