Dublin Bus say that passenger safety is their number one concern after a wheel fell off a bus in the city centre during the week.
The wheel came off the 15b bus at Butt Bridge, close to Liberty Hall on Tuesday afternoon.
Dublin Bus say their drivers carry out visual checks on buses every morning, while there's trained checks every 4 weeks and checks using torquing equipment every 25-thousand kilometres.
However General Secretary of the National Bus and Rail Union Dermot O'Leary says drivers are not qualified to spot if a wheel nut is tight enough.
The company say that this is a completely isolated incident and an investigation is underway.
