Train drivers based at Waterloo are on strike as people return to work after the bank holiday.
SWT drivers are annoyed taxis are being withdrawn
About 200 Aslef members working for South West Trains (SWT) have walked out for 24 hours in a row over taxis.
They say SWT reneged on a deal to pay for taxis for early or late shift drivers, but SWT says the privilege had been "abused" and costs had soared.
The company said any disruption should be minimal and only drivers at the Waterloo depot were taking part.
They represent 200 of the firm's 1,200 drivers.
Further action is planned on 13 and 15 June, unless the dispute is resolved.
SWT said it was disappointed at the strike and said it was doing what it could to resolve the row.