Concrete Foundations for Wooden Bridge

[RPM]

glennmac,

I'm interested to know if you're planning on using one of the 3pt concrete/cement mixers for this job ...?

 

[kadonte]

or possibly?

 

[cowboydoc]

That's exactly how I built my bridge except I used telephone poles and instead of building ramps like they did I buried it level with the ground and I didn't put rails on it. I have had zero problems with mine.

 

[Mark_in_IN]

How many poles did you use? How much did you span? Where did you get them from? Does anyone know if poles would span 25 almost 30 feet & at that distance how many poles would you need.

mark

 

[cowboydoc]

Mark,
On the one I did with telephone poles I used six poles. The span that I had was about 18' over the creek itself. The telephone poles were 30-40' each. I got the poles from my local utility company for $1 each. They had some there that were taller than 40'.

 

[MarkV]

Glenn,
Sounds like you are getting many good ideas. If you are going to use concrete, even with sono tubes, it is alot of mixing. Most concrete companies give you "X" amount of time to unload a truck with no charge. After that point, you could keep the truck and pay a bit extra. Where I am going, is it realistic to have a truck come in and shuttle the concrete to site with your FEL. We often do this with a skid loader when there is no way to get a truck to the site.

MarkV

 

[Mike H]

Glennmac: The bridge you're looking at doesn't have to carry too much load so you're 4x12's should be fine. As an approximation, 2-2x12's on 12' posts will carry about 500 lb/ft or 6000 lb uniformly distributed over the 12'. Your load won't be uniformly distributed, but you'll have at least two beams. I'd space them so your vehicle drives over the beams - otherwise, the 2x6's will easily be the weak link.

I've been playing around with Sonotubes for some foundation work this summer. I put 12" dia. tubes on 2'x2'x12" footings. Mixed with a small portable mixer. For a 60" column it took about 45 min. I used 1/2" rebar in both the footing and column. With this little load, I'd just stick the bar in the column after you've got enough concrete in it to hold it in one place. I'd use a foundation bolt to attach to the beam. Use an 18" bolt so you're at least 6" into the concrete. If you don't put a footing under the 12" column, depending on the bearing strength of the soil, this could be the weak link (w/ poor soil, the column may only carry 1,000 to 2,000 lb ).

This is just based on beam/column design. I'm afraid I don't have any experience designing for washout.

p.s. from a beam bending standpoint, a 4x12 is close to the same as a 10.5" dia. pole

 

[Alan L.]

The problem with a dirt swale is that mine keeps washing away. I put more dirt in from the bank and after a rain its downstream. Of course this means I'm sending my dirt downstream. Either a concrete swale or a bridge would be in order. I like those pictures of the one that was done in Oct '00. I'm only worried about putting all that work into it and having the first flood wash it out. I wonder if putting some sort of spoiler on the upstream side would make the water pressure go over the bridge.

Alan L., TX

 

[glennmac]

Doc,

Could you clarify how many poles you used. In one post you seem to indicate 3; on the other, you indicate 6. I may have located some telephone poles, so the next question is how many should I use. I'm assuming 3 (and probably even 2) is enough for a loaded up compact tractor and small trucks. The other issue is the ability to withstand overflowing water conditions. A 6 pole bridge would be a lot heavier than a 2 or 3 pole bridge.

However many poles you used, did you find no difficulty nailing the crossboards because of the uneveness and undulations in the poles?

 

[cowboydoc]

Glenn,
I used three to span the bridge and I used the other three to put on either side of the creek. I anchored those in the ground cross ways and then layed the other ones on length wise across the creek. I then got some re-rod and cut it off at 6 foot and pounded these through the poles to hold them in place and a little anchoring into the ground. Then I buried them in the dirt so that it was all even with the grade on both side and then nailed my boards on top. Almost exactly how the one guy did his excpet that I used the telephone poles instead of the big beams.

 

[TWINKLE_TOES]

Glenn,

If you go with the telephone poles be cautious when you cut them. Most of the poles that I have used had a glass vial placed in a hole just above the finished grade of the original pole. The vial was filled with some nasty stuff that would weep into the base to preserve the wood. I have no idea what the heck it is. The yardman warned me when I picked up the poles. In spite of his warning I managed to cut one pole at the vial. It was long since empty and no big deal other than a darn dull chain on the saw. The holes for the glass vial had a wooden plug driven in to seal the hole.

Al

 

[glennmac]

TT, thanks for the warning. Not exactly the kind of thing that's intuitively obvious. In fact, if I go that route, I'll make it a point to ask about the glass.

 

[hayden]

So that's where they got the idea for the new bridge entering the Big Dig in Boston

 

[kadonte]

Saw one years ago in Germany so I just had to build one. Besides whats a pond without a bridge over it.

 

[JonE]

Neat project Kadonte!
Glenn, I would just use a product like Quick Crete with fiber glass reinforcement and forget about the rebar. Use the sono tubes, they work great! My neighbor just put up a 40'x60' steel builing on piers using those tubes. Mixed up every 12" pier with my portable mixer and a generator to run it. It took about 7 bags (70lb high strength concrete) per 12"x4' tube. It went faster than you'd think it would. He also had to place bolts in those piers at exact locations.

 

[Gatorboy]

I have read this entire thread and have a great interest in building a bridge myself. Without pictures, it is sometimes hard to visualize what everyone is describing, but I think I have done a fairly good job.

In my case, the far side of the stream in which I need to build my bridge over, is about 5' higher than the near (low) side. If I keep my bridge level, and use sono-tubes of concrete on each end, how do I build the ramp from the end of the bridge to the ground? I would think I would have to build the abuttment on the low side out of a form, like an upside-down 'U' (when looking from the end) so that I could back fill it in with dirt and gravel to create the slope down from the bridge.

Any pictures of any similar projects would be very useful. After two bids of $60,000 and $38,000 to build a bridge, the use of telephone poles have given me new life, and the hope I can do it myself and save much $$$.



Regards,
Dave "Gatorboy" Hoffmann
Fallston, Maryland

 

[Gatorboy]

Well, I have decided to build my bridge with 40' telephone poles -- 3 on each side. I have found a place which sells poles, but NEW ones only. They said that the electric company has decided to dispose of all used poles (however they do that) and not allow the sale of used ones. A class 2 40' pole costs $490. I need at least 7 of these -- 6 for the stringers and 1 cut in half for each end laid perpendicular for the stringers to lay on.

Does anyone have any other suggestions of where I can find these infamous used poles? Let me tell ya, CowboyDoc made the deal of the century by getting his used poles for $1 each!

Oh, and I also contacted the local phone company, and they do not allow the sale of used poles to the public either. Grrrrr...

Regards,
Dave "Gatorboy" Hoffmann
Fallston, Maryland

 

[TWINKLE_TOES]

gatorboy,

I have been able to get all the free poles I want from my local power company. I didn't go thru the front door, just talked with the fellow running the yard where they stack them. I'm pretty sure if I tried to buy them thru the front door I would have gotten the same answer you did. A lot of the poles lacked the structural integrity necessary for a heavy bridge application. My use has been for retaining walls.

Al

 

[Mark_in_IN]

I did some research at the utility I work at and found out that is is up to individual offices. Some sell them for $1 a peice one place gives them away and others don't sell them.

I'm hoping to get 5 poles for my bridge project. Five bucks for poles, wish I could get the decking that cheap.

mark

 

[theboman]

Cross ties. Check for them in your area. They are wonderful for spans.

Bluegrass, Pick It Up!