Anyone who uses the RER A and RER B train lines in Paris might need to think about finding an alternative form of transport on Tuesday.
Drivers on the two commuter lines held a 24-walkout on Tuesday meaning services were drastically reduced, especially at off-peak times. But don't be tepted to get into your car and onto the roads. Authorities reported there were 550 km of traffic jams in the greater Paris region on Tuesday morning - a record for the region.
The strike, which has been called for by four unions to protest over a "dysfunctional" organisation, will run until Wednesday 7am.
On the RER A - Europe's busiest train line - which runs from west to east through the centre of the city and serves the business district of La Defense, only half of normal services will be operating at rush hour.
05:18, le trafic est perturbé sur la ligne (mouvement social) #RERA— RER A (@RER_A) December 12, 2017
For off-peak times services will be reduced even further meaning the 1.2 million passengers who use the line each day will face major disruption.
And trains for Cergy and Poissy will terminate at La Defense.
It will be a similar story for the RER B which serves both Charles-de-Gaulle and Orly airports and carries 875,000 passengers each day.
05:23, le trafic est perturbé sur la ligne (mouvement social) #RERB— RER B (@RERB) December 12, 2017
During rush hour only 50 percent of trains are operating, and for off-peak times only a quarter of services will be running.
All passengers will have to change trains at Gare du Nord, so passengers heading to Charles-de-Gaulle airport will need to ask for help from staff to direct them towards the trains heading to the airport
The image below shows that anyone heading to Charles de Gaule airport will have to head to platforms 30 to 36 which are on ground level. Those heading south to Orly airport via the RER B stop Antony need to head to platforms 43 and 44 which are located underground.
There is at least good news for Metro passengers with services meant to be running as normal throughout the day on all lines. However passengers reported several problems on lines 6 and line 7.
Services on Lines 1, 4, 13 and 14 have been increased to ease the pressure on the RER services.
Bus and tram services are also running as usual.