The U.S. Embassy in Paris informs U.S. citizens that representatives of the four main train conductors’ unions for the RER A have announced their intention to strike tomorrow, Thursday, December 10. RATP officials say that delays on the RER A are likely to be severe, and it is possible that traffic on other lines will be affected as well. According to the RATP website, only one out of every two RER A trains will be running during rush hour; during non-peak hours, only one out of every four will be running. The RATP will run extra trains on Metro Lines 1 & 14 in an attempt to absorb some of the traffic.
The strike is scheduled to begin at 3 am Thursday morning and run through 6:30 am Friday morning. Officials advise that commuters should allow extra time for their travels all day Thursday as well as on Friday morning, as follow-on effects are likely even after the strike’s official end time. For information, please consult the RATP traffic information bulletin (in French), or the Twitter feeds of the RER A and the Metro line(s) that you normally take, if relevant.
http://france.usembassy.gov/usc_travelinfo.html