Train drivers at 16 rail companies will stage a series of fresh strikes next month in a long-running pay dispute, Aslef has announced.The strike, running from Tuesday, May 7 until Thursday, May 9, is expected to cause chaos for commuters.It will see drivers who are members of Aslef walk out in a series of one-day strikes, couples with a six-day overtime ban running from May 6 to 11.