Commuters in Germany will have to wait until Thursday evening to find out whether the trains will be running on Friday.
A labour tribunal is to rule on the legality of a planned three-hour nationwide strike by train drivers on Friday. If it does go ahead, it would be the first such walk-out since 1992.
The GDL union staged a series of small stoppages in July and August to press for a pay rise of up to 31 per cent.
They rejected an offer from state rail company Deutsche Bahn of a 10 percent raise, in return for an increase in hours from 41 to 43 a week.
Drivers in Germany earn around 1,500 euros a month on average, less than their counterparts in neighbouring France and Switzerland and less than drivers who work for private companies in Germany.
An all-out strike by the GDL could cause a loss of some 500 million euros a day.
If the court decides the strike cannot go ahead, the union says it will appeal to the more senior federal tribunal.