Irish Rail is warning customers it does not expect to operate any services on five days over the coming weeks, due to strikes.
Members of the National Bus and Rail Union and SIPTU are to stage the industrial action over pay cuts of up to 6%.
The work stoppages will take place on August 24 and 25, as well as on September 7, 8 and 21.
Irish Rail says the strikes will only serve to disrupt customers, threaten employment and make the company's financial position worse.