Question
they're railroad ties...

Answer
Thanks, I've just never heard them (railway sleepers) named in that way, these Brits hey?

Ok, the creosote, although still maintaining the timber disease free for many years, will have leached any dangerous toxins over time that might otherwise leach free if they were fresh of the block, as it were.

I would use them, and I do use them, without any fear of the toxins that may otherwise exist in fresh ties.

They are great for holding up soil but so are rocks, placed simply one on top of the other, as plants like thyme or sedum grow really well between them and give a great effect but if you have them go ahead and use them, by all means.

Consider placing them on their 'ends' (upright) as this can give a great effect too, if you have enough them that is. Just bury half of them in the ground, maybe with a cement base if they are shallow and they work perfectly in an original way. They also retain larger amounts of soil in this way (they are stronger).

Thanks for any bonus points in advance!

Kind regards

Jonathan Radford, garden designer www.ecologicagardens.com