Commuters faced chaos today as the Tube strike hit services across south west Hertfordshire.
Members of the Rail, Maritime and Transport (RMT) union walked out at 9pm last night as the 48-hour strike began.
The walk-out follows a break-down in talks between the RMT and London Underground over ticket office closures.
Services will start later and finish earlier during the action, which will be followed by a three-day stoppage from 9pm next Monday.
Mick Cash, RMT acting general secretary, said: "Despite the spin from London Underground nothing that they are proposing is about 'modernisation'. The current plans, closing every ticket office and axing nearly a thousand safety-critical jobs, is solely about massive austerity cuts driven centrally by David Cameron and his Government and implemented by Mayor Boris Johnson.
"RMT could have recommended the suspension of this strike action if London Underground had responded positively to our proposal to halt the implementation of these savage cuts, stopping the dire impact they would have the length and breadth of London Underground."