Luas drivers are threatening they could stike 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 since they had to start storing their lunch in fridges at the other end of the Green Line.
They used to keep their meal at the Sandyford depot where they would return to eat it.
But since the new line opened, they now must carry it to Broombridge to store it in refrigerated facilities there.
SIPTU's John Murphy says the drivers are not being unreasonable.
"Would you bring a prepared dinner, that you might be heating in a microwave or maybe a salad, for three or four hours around in a cab and then have to try and have that in half an hour and then back out driving passengers around the city."
SIPTU isn't happy with the cooler bag solution. It wants extra drivers to facilitate a roster situation where they can return to Sandyford if they started there.
Transdev says five extra drivers would cost the company €250,000 euro a year.
The Labour Court says it doesn't 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.