With the Christmas rush underway, travellers are facing widespread disruption in Belgium, as rail unions join a public sector strike.
Trains ground to a halt late on Wednesday night.
Eurostar is not planning to operate international services to and from Brussels.
Bus, tram and metro services have also been shut down as part of the 24-hour walkout over pension reforms.
“We’ll have to improvise how to get to the airport,” one traveller said.
Another added: “I just hope the bus is coming, otherwise I’m going to stay here for Christmas – no, no way! We’re going to share a taxi I think.”
In France, airports are being affected by a separate walkout. Private security staff are on strike for the seventh day, in a dispute over pay.
At Charles de Gaulle airport in Paris, police officers have now been deployed.
Flights at the international hub are said to be operating, but passengers are experiencing some delays.
The French government says it is working hard to ensure planes are not grounded, during one of the busiest travel periods of the year.