Rail passengers face delays, cancellations and replacement buses on Wednesday amid fresh strikes against four rail operators, part of a long-running dispute over the role of guards.
Members of the Rail, Maritime and Transport union (RMT) on South Western Railway, Arriva Rail North, Merseyrail and Greater Anglia will strike for 24 hours.
An earlier strike was held on Monday, with another scheduled for Friday.
Northern said it would run around 1,350 services on strike days, more than half its normal timetable, with most between 7am and 7pm.
South Western Railway plans to run more than 70% of its normal weekday service of 1,700 trains, although there will be rail replacement buses and most routes will see a reduced service.
Merseyrail will run a reduced service, mostly between 7am and 7pm, with a break during the middle of the day.
Greater Anglia plans to run a normal service, with no alterations.
The RMT said it had called for a summit with Transport Secretary Chris Grayling and the train companies aimed at resolving the disputes, but had yet to hear back.
"Every single effort that RMT has made to reach negotiated settlements in these separate disputes with the different train operating companies over safe operation and safe staffing has been kicked back in our faces and we are left with no option but to press ahead with the action exactly as planned," said General Secretary Mick Cash.
"No one should be in any doubt, these disputes are about putting the safety of the travelling public before the profits of the private train companies."
"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."
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.
"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 - instead the RMT called strikes on five train companies to cause maximum disruption to passengers.
"Nobody is losing their job as a result of driver-controlled operation trains - employees have been guaranteed jobs and salaries for several years."