Splice telephone poles

[Norrlandsbonde]

Planning to build a bridge over a stream, with one side resting on a rock and the other on a foundation. The span will be 12 meters! I have telephone poles that are quite thick, but they are only 6 meters long. Can I splice these? And how would you do it to make it as durable as possible? The idea is to have two long poles to lay decking on and possibly a railing on one side, about 1.2 meters wide I was thinking...

 

[Troberg]

I would try to drop a foundation in the middle, alternatively get hold of longer beams. A 12-meter span becomes wobbly.

One could also make a suspension bridge, but then it gets complicated...

Also, have railings on both sides. It's easy to trip. I am myself a "small bridge" owner (30 m in three spans, and it rocks even if it's steel beams), and it has saved me a couple of times...

 

[Norrlandsbonde]

Foundation in the middle becomes unfortunately difficult. Rail on just one side is because I want to be able to sit and fish on the other side

I've considered a suspension bridge and also beams, but transportation becomes expensive even if you can get hold of beams that long...

 

[DIY_freak]

Maybe if you put a post under each joint and bolt them together? The question is rather what happens when the construction fails, do you drown then or just get a little wet?

 

[Norrlandsbonde]

If there is 1.5-2.5 meters deep water under the bridge, then if you can swim, you should be okay.

 

[Troberg]

If you want to fish, a suspension bridge is useless. Too much in the way.

Foundations don't have to be difficult (unless it's very deep). Just set it out in the winter, then you can work from the ice.

 

[corre]

You should be able to bolt U-Beams that are 4m long on each side of the post.
Due to the U shape, you get a locking mechanism that is difficult to break when screwed together.

What weight should the bridge withstand?

 

[Norrlandsbonde]

You could drive down two posts in the middle, 6 meters should be enough, just over 3 meters down in the bottom they can be pulled then... however, I don't think the County Administrative Board would like that...

 

[corre]

You could use galvanized pipes instead in the middle.

 

[Norrlandsbonde]

It should withstand its own weight + 2-3 people, and there will likely be snow on it, so it must endure that weight as well.

 

[Norrlandsbonde]

Galvanized pipes = cost. I have 6 6-meter posts and it would be great if that was enough...

 

[corre]

Tricky, doing it with minimal cost may not make it sustainable over time, or not fully environmentally conscious. But the cost of driving down two poles is probably extensive as well? U-Beam for joining is probably the most sensible, but that costs a penny too.

 

[Norrlandsbonde]

I actually have 2 pieces of 9-meter beams, but they are H-beams if I remember correctly.

 

[corre]

It works just as well if life is high enough. Should probably only be 200mm.
No idea how much it will sag in the middle, or if it can withstand some dynamic load (children jumping) though.

 

[Troberg]

A problem that I have is that, even though it is my bridge, on my land, it quite often happens that trespassers use it.

I know that some planks are bad, some so bad that one might step through them. I haven't had the time to fix it, and instead, I walk so that my weight is directly over one of the steel beams.

But, I suspect, signs, private property, and such notwithstanding, that if any trespasser steps through and gets injured, I risk being held responsible. Not fun...

I actually have 2 pieces of 9-meter beams, but they are H-beams if I remember correctly.

Sounds like a much better solution than wooden posts.

My bridge is built on H-beams, with a wooden joist screwed on top. The planks for the deck are then screwed into these joists. The railing is (if I remember correctly) vertical supports welded (but might be screwed, I didn't build it) into the beam, with planks between. Quite sturdy.

I also think the railings might contribute a bit to reducing sway.