Rail services out of Waterloo will be disrupted this week because of a five-day strike in the long-running dispute over guards on trains.
Members of the RMT union on South Western Railway will walk out from Tuesday, hitting services including busy commuter trains into London Waterloo.
Services will be cancelled or disrupted and the stoppage coincides with the Royal Ascot horse race meeting.
Industrial action was suspended in February when it appeared a resolution was in sight. But the union is renewing strikes after accusing the company of "dragging its heels" in protracted talks over the past few months.
The RMT said SWR company was not prepared to give assurances that its new operational model won't move to driver controlled operation.
According to the RMT, the train company pledged in February that "each passenger train shall operate with a guard with safety critical competencies", which led the union to suspend industrial action.
Union officials said since then it has been "stalemate", accusing the company of "rowing back" on its public pledges.
The company said it met with the union last week and agreed to arrange new dates to continue those talks.