The Spanish union of train drivers and workers, Semaf, has called a four day strike during September.
The 24 hour strikes will take place on September 4th, 11th, 14th and 15th confirmed sources from the union.
The union added that it "did not rule out" the possibility that other unions would also take part in the strikes.
The "lack of progress" in discussions on a collective bargaining agreement by Renfe, as well as a failure to reach an agreement on the subject of human resources "has left us no alternative but to go on strike" the union confirmed.
Another national workers' union, the CCOO, announced last week that it was preparing to strike in September after negotiations broke down with Renfe over calls to increase workforce numbers.
According to estimates by CCOO, Spain's national railway operator needs 1,125 more employees to address "the serious situation of the lack of maintenance on the company's trains".
Train workers are planning to protest outside Spain's Ministry of Public Works on Saturday September 12th.