Culverts/pipes - lots of questions

"Any idea how much weight 18" plastic pipe could hold?"
None. Same for metal. They're only to keep the dirt out of the hole. Deep enough and they'll carry any load, if they don't have dirt on top they won't stand one crossing. Depending on the fill you're using 12 to 18 inches from the road surface to the top of the pipe will carry anything short of a loaded dump truck.
Four-foot diameter pipe? Needs to be deeper. I'm sure there are engineers who would have a table that shows how much deeper for how much greater diameter. Or a formula that says something like,"One inch of depth for each two inches of diameter." The idea is that the dirt spreads the load around the pipe rather than having the weight press down onto it.
"How long should the pipe be for a safe tractor crossing?"
Well, what really matters is how wide the road bed is. If you can approach straight on, three feet wider than the wheels of your widest trailer would be a decent rule of thumb. If the pipe is to be eighteen inches below the surface it should be at least three feet longer than the road is wide. Here again, that depends. What you want is to be able to have the slope from the road to the top of the pipe gentle enough that the dirt doesn't fall away. If it's sand you need longer pipe, if you're going to build a concrete wall on each end six inches overhang would be plenty. /forums/images/graemlins/wink.gif
"Is it easy to join 2 sections of pipe together?"
No. At least, used metal pipe would be hard to do. If you're going to have much or even frequent flowing water you want a good seal. Any openings the water will find and eat away the dirt. First thing you know you've got sink holes between the sections.
"Would it be easier to just buy a longer section of pipe?"
Yes, but...
"Any idea how much corrugated metal pipe costs?"
Like I said, we mostly scrounge. Have old stuff donated. Best we can do with what we have to work with.
"Where can I get culvert pipe?"
I know the 8 to 24 inch plastic pipe is available from Lowes, etc. Not too pricey.
Like most home projects, there is the prime trade-off. The better you do it, the longer before you have to re-do it.
Good luck, Wm
http://www.wimmark.com/culvert_maintenance.htm

I do a lot of "low cost," meaning whatever we can scrounge up, culvert work for the hunt club where I have a backhoe membership. All seat-of-the-pants, no formal training stuff, so any answers I might offer are strictly caveat emptor, and worth what you paid for them."Any idea how much weight 18" plastic pipe could hold?"None. Same for metal. They're only to keep the dirt out of the hole. Deep enough and they'll carry any load, if they don't have dirt on top they won't stand one crossing. Depending on the fill you're using 12 to 18 inches from the road surface to the top of the pipe will carry anything short of a loaded dump truck.Four-foot diameter pipe? Needs to be deeper. I'm sure there are engineers who would have a table that shows how much deeper for how much greater diameter. Or a formula that says something like,"One inch of depth for each two inches of diameter." The idea is that the dirt spreads the load around the pipe rather than having the weight press down onto it."How long should the pipe be for a safe tractor crossing?"Well, what really matters is how wide the road bed is. If you can approach straight on, three feet wider than the wheels of your widest trailer would be a decent rule of thumb. If the pipe is to be eighteen inches below the surface it should be at least three feet longer than the road is wide. Here again, that depends. What you want is to be able to have the slope from the road to the top of the pipe gentle enough that the dirt doesn't fall away. If it's sand you need longer pipe, if you're going to build a concrete wall on each end six inches overhang would be plenty. /forums/images/graemlins/wink.gif"Is it easy to join 2 sections of pipe together?"No. At least, used metal pipe would be hard to do. If you're going to have much or even frequent flowing water you want a good seal. Any openings the water will find and eat away the dirt. First thing you know you've got sink holes between the sections."Would it be easier to just buy a longer section of pipe?"Yes, but..."Any idea how much corrugated metal pipe costs?"Like I said, we mostly scrounge. Have old stuff donated. Best we can do with what we have to work with."Where can I get culvert pipe?"I know the 8 to 24 inch plastic pipe is available from Lowes, etc. Not too pricey.Like most home projects, there is the prime trade-off. The better you do it, the longer before you have to re-do it.Good luck, Wm