Rail passengers are being warned to expect disruption in the coming days because of strikes and an overtime ban by train drivers in their long-running dispute over pay.Members of Aslef at 16 train operating companies will refuse to work overtime from Friday until December 9 and will stage a series of strikes between December 2 and 8.Train companies said they will operate as many trains as possible but there will be wide regional variations, with some operators running no services at all on strike days.