About 900 members of the Aslef union working for South West Trains have gone on strike in an ongoing dispute.
The walk-out was sparked after managers drove trains during previous industrial action in a row over drivers using taxis to get to and from work.
The action will be followed by two further strikes on 8 and 11 September unless the deadlock is broken, the union has said.
The dispute started earlier this year when there was a disagreement involving drivers over the use of taxis. Managers were used to drive trains but Aslef said South West Trains contravened an agreement they would only drive trains in cases of health and safety or the possibility of civil unrest.
The union also raised concerns over safety, claiming that one manager had not driven a train for 10 years. The company has insisted only fully-qualified managers had driven trains.
South West Trains managing director Stewart Palmer said: "The unions claim we have breached an agreement only to use managers to drive trains in exceptional circumstances.
"We believe that a strike is an exceptional circumstance and that the prospect of leaving thousands of passengers stranded at stations and the subsequent overcrowding could have led to very real safety concerns."
Drivers on the Heathrow Express from Paddington to Heathrow Airport are also on striking on Tuesday in a separate dispute.