UPDATE on DIY bridge (long post)

   / UPDATE on DIY bridge (long post)
  • Thread Starter
#32  
Hi Gary. I dont post on here a lot, but your topic caught my attention. I have some Bar Joists that I drug home from a commercial job site. They can carry a pretty large load. I was going to put a bridge accross my creek with them, just never got to it. Here is what I am talking about: https://qph.fs.quoracdn.net/main-qimg-a525cf5443d250d9e449e6f275576fdf
I got mine free and they were built the wrong size so they were going to toss them. You could check with a local fabricator that makes these to see if they have any rejects or just to see what they would charge to fabricate them for you.
Yes Sir, I have my eye open for some but so far no luck. Any idea how tall they would need to be to carry the weight of, say a log truck and how close they would need to be? Like 2’OC?
 
   / UPDATE on DIY bridge (long post)
  • Thread Starter
#34  
I’m not finding that post now. I’m thinking it was posted by Jstpssn but I’m not sure. Sorry
Might also be under my first post ‘DIY Bridge’ but I can’t find it anywhere.
 
   / UPDATE on DIY bridge (long post) #35  
I would look for a company that builds or installs precast concrete buildings. They will have some flawed pieces 20-40' long. Probably best to get them to deliver one. You should ask them about stress, but I have found they are fine for cars and pickups.
Also, I remember my dad built farm bridges with old railroad rails with rough sawed 2x10s bolted across them. Kind of springy, I never saw one fail.
 
   / UPDATE on DIY bridge (long post) #36  
I have walkover bridge like that not sure I would trust my truck on it. The 40' rails are springy just walking across.
 
   / UPDATE on DIY bridge (long post) #37  
Railroad rails are probably designed to span a gap of not more than about 2 feet.

rail-unloading.jpg

Bruce
 
   / UPDATE on DIY bridge (long post) #38  
To me as long as the road before and after the culvert is not too elevated and since there is practically no banks you will be fin, by putting a ''restriction'' in the middle the water will rise and flow around it.

Yes, that's exactly what happened to us. We watched from a hillside as a whole town's bridges and culverts washed away for different reasons - but the most common cause seemed to be that as the creek became a river, it would cut channels around obstructions in moments, undermine them, and then removed them.

It was awesome to watch, but what I'll remember is the incredible noise - like a prolonged train wreck that went on all day.

I now believe that there will always be a large enough flood to wash away whatever kind of bridge we build - unless it spans a ravine and is enough taller that the ravine to freely pass trees, trucks, and houses underneath.

That's why I said my new rule of thumb is If you have to drive downhill to get to the bridge, it probably isn't going to last.

Yet, even if flooding is becoming more common, most of the time there isn't a flood. It's water as usual. So I think the trick is to build something that will still be there when the water goes down. I like that reinforced concrete low water crossing with the sloped upstream and downstream sides.

rScotty
 
 
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