Rail passengers in the south of England are facing significant disruption today as train drivers on Southern services begin three days of strike action.
No services are expected to run on the entire network as drivers begin a 48-hour walkout.
A further 24-hour strike is set for Friday.
Around 300,000 passengers usually travel on 2,242 Southern services every weekday.
Passengers on the key London to Brighton route have suffered months of disruption in the dispute, which is centred on whose job it is to close train doors.
However, this is the first strike by Aslef drivers.
Mick Whelan, general secretary of ASLEF, said: “Industrial action is always the last resort.
“We don’t want to inconvenience the travelling public, and our members don’t want to lose money.
“We are going on strike because we have been forced into this position by an intransigent management that has not been prepared to negotiate with us.
“Even now, all we want is for the company to sit down with us and negotiate - properly, sensibly and in good faith, not to simply restate their old entrenched position - and do a deal for the benefit of passengers, staff and, of course, the company.”
Southern earlier warned passengers not to travel.
The operator will close most Southern routes, although there will be a limited Gatwick Express service to and from London Victoria.
UK transport secretary Chris Grayling said he did not have the lawful power to intervene in the dispute.
He branded the action a “deliberate act of militancy”.