Luas drivers are threatening strike action over the issue of packed lunches.
A row has erupted since the opening of the new tram line changed the location of drivers' break-time.
Transdev, which runs the Luas, says it will pay for cooler bags for the packed lunches of tram drivers who start their shift in one depot, but are required to eat in another. About 100 cooler bags have been issued.
Drivers who started their shift at the green-line Sandyford depot formerly returned to eat it in that depot. However, since the new line opened they now must carry it to Broombridge and eat it there.
SIPTU is not happy with the cooler bag solution and wants five extra drivers to be hired at a cost of €250,000 a year, which would allow their drivers to continue returning to Sandyford, without impacting schedules.
Transdev has said the cooler bags are a reasonable solution to the issue, and avoid the cost of hiring five more drivers.
The Labour Court says it does not usually concern itself with the function of cooler bags but has asked they be risk-assessed.
SIPTU says a ballot of drivers is likely to reject that proposal, meaning industrial action could be on the cards.