Many commuters and tourists in Germany's capital were left high and dry on Monday amid a warning strike by workers at Berlin's public transport authority BVG.
The strike, called by the union Verdi and scheduled to last 24 hours, got underway at 3 am (0100 UTC). Trams, underground trains and most buses were not operating.
German media have reported large traffic jams in and around the city, with commuters forced to use private cars to get to work.
Trains still running
However, the suburban train network was unaffected by the strike. In a press statement on its website, operator S-Bahn Berlin warned that although its services would be running, trains could be fuller than usual. It said it was laying on more services to help commuters.
BVG staff are demanding more pay and better working hours. The warning strike comes after the latest round of talks between BVG and unions broke down on Thursday.