Railroad tie building tips?

I have access to a large number of railroad ties and am curious about two things:

What is their vertical load bearing capacity?

What is their horizontal load bearing capacity?

How safe are treated railroad ties for humans when covered with polyethylene (plastic)?

Has anyone had experience building with railroad ties? Any tips or gotchas?

I can throw a few tidbits at you from experience:

-A two wheel dolly with pneumatic tires is your best friend with RR ties. Makes it super easy to flip em, move them, and pivot them. With a little practice, you can even lift to stack.

-Beware the metal bands that are pounded into the ends if you intend to cut. It does not run all the way through.

-Tar is a factor. Nothing will stop tar from oozing out of your ties on a hot day and I've got the stains to prove it.

-The treatment doesn't last forever. I watched a spectacularly horrifying bloom of termite swarm coming out of a tie wall a couple months ago. Old ties though, likely from 1872 when the roailroad went through my back yard so assuming you have newer ties that might not be such a factor.  

Railroad ties are darn handy, but personally, I'm really leery of using them for any food garden type projects. Coal tar creosote is a really nasty carcinogen.

RR ties are injected with a variety of poisons to resist being 'eaten' by bacteria and ants, etc. The poisons kill the ants and bacteria's before they can do any harm. Did you know that humans and various bacteria's share from 2 to 20 % DNA? And ants and humans share 30%? I can't at the moment cite the science to prove poison used on RR ties will kill you. But, logically, if something kills something and you are made up of the same stuff as the dead somethings, you can probably expect a bad day. I can not think of one single reason why anyone, especially a permaculturalist, would want to import poisons onto their land or into their life. To do so would be a very foolish short term decision to solve a long term problem, thereby creating a much longer, bigger problem later on.

P.S. This is the same reason I believe that using treated lumber or car tires are also a bad idea for building, ..anything. Tires are made of very toxic stuff, so is treated wood. The tires may take a hundred years to rot away. Maybe even 2 hundred. I don't know. But sooner or later, somebody is going to have poison in their soil from something we did in our time. And that just isn't very nice.

Design loads are a function of timer type, condition, dimensions and span as a beam or height as a column.

Thats the easy part.

I have built with many, but what do you have in mind to use them on?

John C Daley wrote:I have built with many, but what do you have in mind to use them on?

Considering using them in an earth berm construction for perhaps vertical (if I can get them long enough) and horizontal purposes. I'm considering wrapping them in plastic to reduce their leeching toxic material into the living space and ground. I have so many at my disposal that it's a hard resource to ignore.

EARTH BERM
Earth covered building
House or shedding?
What size?
Whereabouts?

If you protect any plastic with a layer of geo fabric or shade cloth that will help prevent tears.
If you construction drainage that drains and backfill against the wall with rock to the top of the wall, no moisture should get near in.
It will also prevent water coming into the building.

You, will need to have foundations for the wall that stop it sliding the lower ends moving into the building, which may also finsih as your floor.
I suggest reinforced concrete.

The only thing I can add about building with RR ties is the fact that they eat up chainsaw chains or the blades on anything you try to cut them with.