Members of the Rail, Maritime and Transport (RMT) union were said to be “solidly supporting” walkouts at four train operators in the long-running dispute over the role of guards.
Industrial action today follows strikes on Monday and Wednesday, affecting services run by Arriva Rail North (Northern) which runs services in Yorkshire, South Western Railway (SWR), Merseyrail and Greater Anglia.
The RMT has criticised Transport Secretary Chris Grayling for not responding to its call for a summit to try to break the deadlock.
Alex Hayman, of consumer group Which?, said: “Frustrated passengers who face yet more disruption to their rail services will be disappointed to find out that their rights to compensation when delayed as a result of a strike are surprisingly complicated.
“You can only claim compensation during a strike if a train was delayed for long enough to qualify or if it didn’t turn up at all, based on the revised timetable.
“If operators aren’t planning to run any services whatsoever, then unfortunately you can’t claim compensation.”
RMT general secretary Mick Cash said: “RMT members remain rock-solid in each of the separate disputes across the country over rail safety this morning, on the final day of this phase of action, as we continue to fight to put public safety, security and access before the profits of the train operating companies.
“Earlier this week we wrote to Transport Secretary Chris Grayling calling for summit talks under an independent chair to break the deadlock in these long-running disputes.
“He has refused to respond but managed to take time off during his busy schedule this week to stand up in Parliament to defend to the hilt Britain’s rip-off private rail companies.
“His lack of interest in rail staff’s concerns for passenger safety is a disgrace.
“It makes no sense at all that we have been able to agree long-term arrangements in Wales and Scotland which secure the guard guarantee and which underpin the basic principles of safety, access and security for the travelling public.
“If that rail safety guarantee is right for Wales and Scotland then it must be right for the rest of the UK.”
A Department for Transport spokesman said earlier this week: “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.
“He offered guarantees of employment to members who currently fulfil the role of the second person on the train beyond the length of the franchises.
“Nobody is losing their job as a result of driver-controlled operation trains - employees have been guaranteed jobs and salaries for several years.”
Northern is today running around 1,350 services on strike days, more than half its normal timetable, mostly between 7am and 7pm.