Never. Used to use one at least twice a day, horses always fine with it but ask BR to check it's functioning right for you. If they don't know, they can't do anything about it.
How strange and slightly scary!
Its funny we use one occasionally- Used to be a regular hack but have moved yards and however many times we used it my horse hated it- He would literally almost feel with his hoof before stepping out then leap across, I always thought it was the weird kind of spongy flooring
It is quite possible for your horse to get an electric shock especially on an electric line if the earth rail is not correctly earthed. I would immediately contact Network Rail as it could also effect pedestrians and dog walkers. There should be a telephone for Network rail at the crossing point. I would aslo ask you to report this on the www.horseaccidents.org.uk web site as this relates accidents to specific locations. If you require any further asistance then please do not hesitate to contact me. Peter Natt BHS Volunteer access/bridleway officer. E-mail: peter.natt@btinternet.com