Train passengers face another day of disruption as union members at four rail firms stage the latest 24-hour strikes in disputes over safety.
Services on Greater Anglia, Merseyrail, Northern and South Western Railway, including its Isle of Wight Island Line, are likely to be affected on Wednesday.
RMT union members also walked out on Monday and plan to again on Friday.
The Department for Transport denied the dispute was about safety.
It said rail companies would "keep passengers moving".
The disputes the union has with rail firms include concerns over the role of guards, fears over safety and job losses surrounding plans to introduce new driver-only operated trains.
RMT union members have been told not to book shifts between 00:01 and 23:59 GMT on strike days.
Services during strike action:
- Greater Anglia said it was "very disappointed that the strike is going ahead" and plans to run a full service
- Merseyrail said "unfortunately" it would run a reduced service in and around Liverpool between 07:00 and 19:00, but with a break during the middle of the day. There will be no trains on Kirkby, Ellesmere Port or Hunts Cross lines
- Northern, which covers north-west and north-east England, said it was "focusing on running as many trains as it can" and will operate about 1,350 trains on strike days - roughly 60% of its normal services between 07:00 and 19:00
- South Western Railway, which operates in areas including London Waterloo, Reading, Exeter and Southampton, said it had "offered assurances around the need for more guards in the future" and planned to run about 70% of its normal services, while there would be bus replacements on its Isle of Wight Island Line
RMT general secretary Mick Cash said: "Our members are standing firm this morning in the separate disputes across the country in defence of rail safety and the role of the guard.
"This week, in the midst of the Tory reshuffle shambles, we called on Transport Secretary Chris Grayling to organise summit talks to move these disputes forwards. We have had no response.
"Mr Grayling's silence speaks volumes and, with today's damning NAO report into the Southern Rail fiasco, it is becoming clearer by the minute that all the Tory government are interested in is protecting the fat profits of the greedy private rail companies regardless of the impact on services and safety.
"The strikes today are about putting public safety before private profit."
0720 train to Manc, only 2 carriages and already full when arrives at NLW! passengers are prepared for #RMTStrike days in advance but only two carriages arrive to take double the No. of passengers? @northernfailz #totalletdown #leftontheplatform #stranded @BBCNWT— Nicola Gleave (@Superstar100777) January 10, 2018
Yet another train journey stood just cms from a fellow commuters face... when will passenger’s (the customer) safety be considered? This is appalling. Will it take a tragedy for these companies to learn? Shame on them. #RMTstrike #unsafe @SW_Railway @FirstGroupplc @BBCNews— Mr J to you (@JeffriesCraig) January 10, 2018
@SW_Help @SW_Railway Frayed tempers at Eastleigh train station this morning. Oddly enough queuing customers with bikes don’t appreciate train doors being closed on them and then being shouted at to ‘Calm down’ by your contingency staff. Not helpful. #mustdobetter #RMTstrike— André Cocuccio (@andrecocuccio) January 10, 2018
Playing an excellent game of Sardines this morning on the train thanks to RMT. I must say we're doing a bloody good job of packing ourselves in, but who is looking for us? #RMTstrike— Mimi Doulton (@MimiDoulton) January 10, 2018
Mr Cash said the agreements had been reached in Scotland and Wales to keep guards on new modern trains.
A Department for Transport spokesperson 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."