The head of the National Bus and Rail Union (NBRU) says you can't have "people packed like sardines on trains and buses" if the public is being asked to follow social distancing advice over the coronavirus.
The union is calling for a 'major scaling back' of the capacities of bus and train services in response to the ongoing COVID-19 outbreak.
They've written to Dublin Bus, Irish Rail, Bus Éireann and the National Transport Authority outlining their concerns.
Dermot O'Leary, general secretary of the NBRU, spoke to Newstalk Breakfast this morning.
He explained: "Our frontline staff are concerned with the amount of interaction and capacity issues with regards bus and trains.
"You have a double-decker bus, depending on the seat number, holds about 75 people... we see a situation where that would be scaled back to less than half to [put] the social distancing space between them that's being recommended by all the health experts.
"It's laudable that a lot of firms are telling their people to stay home, but that's not practical in all cases."
Mr O'Leary says the number of journeys on public transport will likely reduce as the coronavirus outbreak develops over the next days and weeks.
However, he suggested measures still need to be put in place to reflect the expert advice on social distancing.
He said: "I don't think the word overreaction fits in the current lexicon with what's going on.
"I don't believe this is panic - I think this is a practical measure.
"There's no point in experts telling us to maintain a metre of a distance between each other, and then having people packed like sardines on trains and buses."
Mr O'Leary stressed that bus and train drivers have the same concerns as the rest of the public when it comes to their own health, the health of their families, and the health of people in the wider community.
He said his union is simply asking that the trade unions representing frontline transport are involved in any decision-making process.