On Monday (January 22) the country's train drivers' union - the GDL - called for a fourth round of strikes from early Wednesday (January 24) until the following Monday (January 29).
The move escalates a wage dispute with Germany's leading rail operator.
And it comes just days after the union turned down a new proposal made by Deutsche Bahn.
GDL leader Claus Weselsky said Deutsche Bahn's latest offer shows it has no intention to reach an agreement.
The rail operator said it relies on compromises and accused the GDL of ramping up the dispute.
It said it was irresponsible not to talk when there was a new offer of a 13% wage rise.
Deutche Bahn and the GDL have fought over a collective wage agreement since the start of November.
The union sought a reduced working week for its shift workers - from 38 to 35 hours - on current wages.
Deutsche Bahn has offered flexibility on working hours but refused to reduce them without a pay cut.
This week's action would be the latest to hit Germany and cause headaches for Chancellor Olaf Scholz's coalition.
Train drivers went on strike earlier this month.
While German farmers also launched nationwide protests against subsidy cuts in early January, blocking roads with tractors.
