Rail workers at five train companies are said to be “solidly supporting” strikes in the long-running dispute over the role of guards.
Services were disrupted, with cancellations and replacement buses in some parts of England because of the latest walkout.
Picket lines were mounted outside stations across the country, while Transport Secretary Chris Grayling was urged to convene a special summit to try to break the deadlock.
Members of the Rail, Maritime and Transport union (RMT) were walking out on Monday, Wednesday and Friday on South Western Railway (SWR), Arriva Rail North (Northern), Merseyrail and Greater Anglia, and on Monday on Southern.
Northern said it would run around 1,350 services on strike days, more than half its normal timetable, with most running between 7am and 7pm.
SWR plans to run more than 70% of its normal weekday service of 1,700 trains, although there will be rail replacement buses and arrangements to have tickets accepted on other train companies.
Greater Anglia said it planned to run a normal service, with no alterations.
Merseyrail will run a reduced service, mostly between 7am and 7pm, with a break during the middle of the day and no trains on the Kirby, Ellesmere Port or Hunts Cross lines.
Southern, which was facing its 39th RMT strike on Monday, said it planned to run a normal service on most routes, but advised passengers to check for any last-minute changes before they travel.
RMT general secretary Mick Cash said: “RMT members remain solid and united in each of the separate disputes across the country over rail safety this morning as we continue to fight to put public safety, security and access before the profits of the train operating companies.
“Today we have written to Chris Grayling calling for summit talks under an independent chair to break the deadlock in these long-running disputes.
“We expect a positive response to this important initiative and we welcome the support of both the Labour Party and the TUC for our proposal. It offers a real chance of progress.
“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: “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.
Commuters ride a crowded South Western Railway train on the Portsmouth to London Waterloo line (Carey Tompsett/PA)
“Nobody is losing their job as a result of driver-controlled operation trains – employees have been guaranteed jobs and salaries for several years.”