Iarnród Éireann has questioned the "basic intelligence and competence" of some truck drivers after it emerged that two bridges in Portlaoise have been hit by trucks 30 times this year alone.
This is despite the installation of improved road height signage and an advance infrared system at the bridges warning drivers when their vehicle is too high.
According to the company, Mountrath road bridge, with 17 incidents, and Mountmellick road bridge, with 13 incidents, are by far the two most struck bridges in the country.
The third most hit bridge, located on the old N11 just outside Gorey in Wexford, was struck for a fifth time yesterday, the company's spokesman, Barry Kenny, said. This bridge does not have the infra-red signage in place.
In a statement yesterday headed "Dumb and Dumber!", the company described truckers who pass through Portlaoise as "the dumbest in Ireland".
"The basic intelligence and competence of drivers involved in these incidents must now be called into question," Mr Kenny said. "The infra-red technology triggers a large motorway-style light display to flash the message 'vehicle too high - divert now' at the nearest junction to the bridge to alert drivers whose trucks exceed the permitted height."
Mr Kenny stressed that Iarnród Éireann regards bridge strikes as the single most likely cause of a serious rail safety incident on the network. They can also cause significant delays to both rail and road services, he said.
This year is on course to be the third worst year for bridge strikes on record, according to Iarnród Éireann.
Jimmy Quinn, spokesman for the Irish Road Haulage Association, said it has done a lot of work with Iarnród Éireann on the issue.
"Anybody who hits a bridge in those circumstances [ in Portlaoise] deserves to get a bang on the head," he told The Irish Times. "It is beyond me."