Irish Rail has refused to withdraw its 'dumb truckers' campaign which aims to raise awareness about the number of bridge strikes.
The company has been criticised by road hauliers, who say the campaign is disparaging to lorry drivers.
Sixty-eight bridges have been hit by a truck so far this year. Irish Rail said the issue caused significant disruption to passengers and could have a significant cost.
The Irish Road Haulage Association is threatening legal action.
However, Irish Rail spokesperson Jane Cregan said she stood over everything the company has said.
"There is a basic intelligence question here if you cannot know how high your load is," she said.
"Not only is it a safety issue for us, but it discommodes thousands of our customers for long periods of time as we have to assess those bridges structurally to make sure they're safe before we can let traffic run again."
Irish Rail said that in 2014, there were 85 bridge strikes across the network, but this year to date alone there have been 68 bridge strikes. DART has seen the largest increase in the number of collisions with 25 taking place this year already, compared tpo 12 in the same period last year.
The company added that hitting of bridges by large vehicles is one of the greatest safety risks it faces.