Rail workers are staging fresh strikes at four train operators, claiming that support from the public for their campaign over guards is "flooding in".
Members of the Rail, Maritime and Transport (RMT) union at Southern, Merseyrail, Arriva Rail North and Greater Anglia were said to be "solidly supporting" the second 24-hour walkout of the week, with no sign of the deadlock being broken.
Workers on the new South Western Railway franchise are set to join the strikes after voting heavily in favour of industrial action in a similar row over the role of guards and driver-only trains.
Services were running in all the affected areas, although there was some disruption because of the action.
The Southern dispute started 18 months ago and is now one of the longest in the transport industry.
RMT general secretary Mick Cash said: "RMT members stand solid, united and determined this morning in the latest phase of strike action in four separate disputes, which are about putting safety, security and access to services before the profiteering of these rip-off private rail companies.
"Political and public support is flooding in as our communities choose to stand by their guards against the financially and politically motivated drive to throw safety-critical staff off our trains.
"Again this morning I am calling on Prime Minister Theresa May and Transport Secretary Chris Grayling to call off the centrally imposed blockade on serious talks in these disputes and allow us to get on with genuine negotiations with their contractors."
Greater Anglia was planning to run a full service on Thursday, and Southern said there would be a normal service on most of its routes.
Arriva Rail North was aiming to run around 1,200 services across the North - 46% of its normal timetable - on both days between 7am and 7pm.
Most Merseyrail services were running between 7am and 7pm, with a break during the middle of the day, and some stations would be closed.
A Southern spokesman said: "Today will be the 36th day of RMT strikes and we, like our passengers and the vast majority of our colleagues, simply want an end to this unnecessary dispute."