Irish Rail has said that it is "unforgivable" for hauliers not to know the height of their lorries and the height of the bridges on their routes.
The comment came following four separate incidents in which lorries hit rail bridges and delayed services.
The first incident took place at a bridge in Monasterevin in Co Kildare at around 11.30am yesterday, delaying the 11.35am service from Dublin to Galway by 50 minutes.
The second took place at a 3.5m bridge on South Lotts Road in Ringsend at approximately 1.30pm.
The third truck hit the bridge beside Connolly Station on Amiens Street in Dublin city centre at around 7.30pm.
These incidents delayed DART services by between 15 and 20 minutes.
None of the bridges were physically damaged, but each of the structures had to be examined after being hit.
A fourth collision happened this morning at the Iarnrod Eireann bridge near Clonard on the R160 road in Meath.
No structural damage was caused to the bridge and there were no knock-on delays for passengers.
Irish Rail says there has been a fall in the number of such crashes in recent years.
In 2005, there were more than 200 bridge strikes. That fell to 61 last year.
Speaking on RTÉ's Morning Ireland, Irish Rail spokesperson Barry Kenny attributed it to increased co-operation between Irish Rail, the Irish Road Haulage Association, gardaí, the Railway Safety Commission and others, as well as fewer lorries on the road in a recession and the opening of the Port Tunnel.
However, Mr Kenny said that yesterday's incidents proved that there was no room for complacency.
"It is a basic rule of the road for truckers, that they know the height of their vehicle and that they know the height of the bridges that they will encounter on their route."