Strikes have brought public transport services in greater Athens to a halt, causing traffic jams as unions protest against austerity measures in crisis-hit Greece.
Commuters pooled cars and taxis to get to work as Tuesday's 24-hour strike stopped all state-run urban transport services.
A general strike Wednesday is set to ground flights, close schools and disrupt services.
The latest action is in reaction to a shake-up of Greek labor rules that includes fresh pay cuts and involuntary staff transfers in the public sector.
The Socialist-led parliament is due to pass the legislation late Tuesday. Government officials say the overhaul is required to continue receiving loans from a euro110 billion ($146 billion) international bailout fund.