Luas workers have served plans for six further days of strike action this month and in May.
There will be five full day strikes in April and May, as well as a four-hour stoppage on another day.
These will be on April 28th, May 4th, May 13th, May 20th, May 27th and a partial stoppage on May 26th.
This is in addition to the strikes due to take place on April 23rd and 24th.
It comes as SIPTU and Luas operator Transdev remain deadlocked in a row over pay.
Management say they are open to a new pay proposal for drivers, as long as it is reasonable.
The most recent deal at the Workplace Relations Commission (WRC) was rejected by them.
Transdev, the company which runs the Luas - says it will take stock and take legal advice on what courses of action are open to it.
SIPTU spokesman Owen Reidy says there are three major sticking points for Luas drivers.