Rail users in England are facing disruption because of strike action by members of train drivers' union Aslef.
Train companies are not using a new law allowing them to tell some staff to work so that a minimum level of services can run.
There has been service cancellations and delays on strike days since Tuesday 30 January, and further disruption is expected on Monday 5 February.
Different operators have been affected on different days, with some running no trains:
- Monday 5 February: Great Western, CrossCountry, Chiltern
There was no strike action on Sunday 4 February, but on Saturday 3 February, West Midlands Trains, Avanti West Coast and East Midlands Railway services were impacted by walkouts.
Aslef members are also refusing to work overtime between Monday 29 January and Tuesday 6 February. This may cause some cancellations and delays.
Passengers are advised to check before they travel. The latest information can be found on National Rail.
Some of the affected train operators run services into Scotland and Wales.
The government passed a new law which means train companies can require enough staff to work on strike days to run 40% of services.
Currently, few or no services usually run when train drivers strike.
The Department for Transport said it expects employers to use minimum service levels "if appropriate to do so, and to deliver the best possible service".
But none of the operators affected have done so, which Prime Minister Rishi Sunak has described as "disappointing".
The rules are complicated to put in place, says BBC transport correspondent Katy Austin. One source told the BBC it means co-ordinating a reduced timetable with other operators in a short space of time.
Plus, unions strongly oppose them.
Train operator LNER, which operates on the East Coast Mainline, reportedly planned to use the rules during a walk-out in February.
In response, Aslef called for five extra days of strikes, before both sides rowed back.
Industrial action by Aslef and the RMT union has meant huge disruption over the past couple of years.
In November last year, RMT members, including guards and ticket office staff, voted to accept a pay offer. This included a backdated pay rise of 5% for 2022-23 as well as job security guarantees.
Their acceptance means they will no longer be involved in industrial action until at least the spring.
However, talks with the RMT over future pay deals and working practices will continue.
Unions in disputes need to reballot members every six months to see if they want to continue with industrial action.
Currently, unions are obliged to give at least 14 days' notice of any strike action.
Rail passengers with advance tickets can be refunded fee-free if the train they are booked on is cancelled, delayed or rescheduled.
If passengers have a return ticket they may also be entitled to a fee-free refund if any part of the journey is cancelled due to strikes.
Season ticket holders (flexi, monthly or longer) who cannot travel, can claim 100% compensation for strike dates through the Delay Repay scheme.
Aslef is seeking better pay for its members.
However, train operators say ways of working need to change for wages to rise, because of financial challenges and fairness to taxpayers.
Aslef says drivers are being asked to sacrifice working conditions in exchange for a below-inflation wage increase.
In April 2023, Aslef's executive committee rejected 4% pay rises for two years in a row. This was on condition that they would accept industry-wide changes to driver training, and negotiate changes to work patterns at individual operators.
There have been no formal talks since.
The government controls how much money is on the table and has the final say over what is offered. Ministers and industry negotiators have urged the union to give members a vote.
The average salary of rail workers in 2022 was £45,919, according to the Office for National Statistics (ONS).
If drivers are excluded (because they tend to be members of the Aslef union, not RMT) its estimate is £39,518. However, the RMT union said that figure was too high because it does not include rail cleaning staff.
The ONS says median pay for "train and tram drivers" is just under £59,000.
Train companies and the government say the offer rejected by Aslef would take average train driver pay to £65,000.
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