Image copyright Neil Hall Image caption
Fresh strikes are expected to cause more disruption for rail passengers in the latest 24-hour walkout over safety.
RMT union members at Northern, South Western Railway, Merseyrail and Great Anglia are taking action for the third time in less than a week.
The union says scrapping guards and introducing driver-only operated trains risks passenger safety.
But the rail companies have insisted the move is safe and already widely used.
Picket lines are likely to appear at railway stations affected by the strike, and passengers are facing delays, cancellations and replacement buses in some parts of the country.
All four operators said some services would still be running:
RMT general secretary Mick Cash said: “It is frankly ludicrous that we have been able to negotiate long-term arrangements in Scotland and Wales that protect the guards and passenger safety, but we are being denied the same opportunities with rail companies in England.
“This suspension of normal industrial relations by the employers has to end if we are to make progress towards a solution that guarantees safe rail travel for all.
“RMT stands ready for talks in each of these separate disputes.”
Image copyright PA Image caption
A Department for Transport spokesman said: “This is a dispute between a private company and the RMT.
“However, the transport secretary recognises the disruption caused to passengers and has met with union leaders on several occasions, including as recently as December, to help bring an end to the strikes.
“Nobody is losing their job as a result of driver-controlled operation trains, employees have been guaranteed jobs and salaries for several years.”
Source: BBC News