Thanks to everyone who replied so quickly. The hives would definitely be out of site from the rail line as the embankment is quite high and well vegetated with goat willow trees, brambles, rosebay willow herb, amongst other stuff.
I have found a potential out apiary site with a rail line along one side of the site boundary. The foot of the rail embankment looks like a good position for the hives, but I'm wondering if the bees will be affected by any vibration from passing trains. It would be helpful to hear from anyone...