Rail travel around Great Britain will be severely disrupted again this weekend after the second 24-hour strike in three days started on Saturday morning.
Thousands of members of the RMT union working as train staff at 14 operators are on strike in the long-running dispute over pay and jobs.
Passengers have been urged to check before travel, with some operators advising to attempt to travel by train only if absolutely necessary.
Just under 50% of train services are expected to run in total, but with wide disparities in regions and operators.
With signallers not on strike, trains operated by transport authorities in Scotland and Wales and within London and Merseyside are running.
But some routes around England will be closed entirely, with all three nations of Great Britain affected by severely reduced cross-border services, particularly on LNER, and on Avanti to north Wales.
Other long-distance operators, including Avanti, GWR and East Midlands, will run hourly intercity services.
CrossCountry, TransPennine, West Midlands, Northern and Chiltern will all cut trains back significantly from normal routes.
Some networks in the south are expected to be badly hit, with most stations on SouthEastern closed, and South Western and Southern affected by engineering works.
Only C2C and parts of Greater Anglia are expected to remain largely unaffected by the action.
Across the railway, disruption could persist early on Sunday. The industry body, the Rail Delivery Group, has urged passengers to check before they travel for updates.
The 14 train companies where staff are striking are: Avanti West Coast; C2C; Chiltern; CrossCountry; East Midlands Railway; GTR (Thameslink, Great Northern and Southern); Great Western Railway; Greater Anglia; LNER; West Midlands, including London Northwestern Railway; Northern; South Western Railway; Southeastern; and TransPennine Express.
Further strikes are scheduled by RMT train staff for 30 March and 1 April.
The industry has urged the RMT to call off further strikes and put the 9% pay offer made by train operators to its members for a vote.
Network Rail is not currently facing strikes, with RMT members voting in a referendum on a pay offer, and the result due from Monday afternoon.