Tailgating, particularly on the M50 motorway, is "all too common in this country", a High Court judge has said.
Mr Justice Seamus Noonan made the comment when he awarded €17,237 to Tanya Ryan, 32, who sued over a multi-vehicle collision on the M50 on March 19, 2015, during the 7am rush hour.
He found Ms Ryan, Canterbrook, Trim Road, Navan, Co Meath, 25% liable and a truck belonging to David McEntee Transport, Ashbourne, Co Meath, 75% liable for the accident.
He did not accept her claim she was hit from behind by an unidentified vehicle but said she had lost control after braking hard while travelling in the fast lane.
The truck driver was not keeping a proper lookout and was unable to stop causing the subsequent collisions, he said.
She had sued the truck company, the drivers of the three other cars involved and the Motor Insurers Bureau of Ireland (MIBI) which compensates victims of untraced or uninsured motorists.
Mr Justice Noonan dismissed the cases against the three car drivers and the MIBI.
Mr Justice Noonan said Ms Ryan was mistaken in her belief she was travelling at 65kph because that would be "an extraordinarily low speed" in the fast lane.
Other witnesses, in the middle lane, said they were driving at between 75kph and 80kph.
She was also mistaken in her belief she had been pushed from behind by the unidentified vehicle which she said had driven on after she was hit and had spun around and ended up facing the wrong direction in the middle lane.
There was no damage to her rear bumper and none of the other drivers saw the unidentified car that had been behind her making contact with her, the judge said.
He believed she may have reconstructed in her own mind what happened since then.
She also said she had been driving a "good car length" behind the car in front of her.
"Tailgating is all too common a problem in this country and particularly on the M50 in my experience", he said.
"And because she was too close to the car in front of her, her reaction was to brake hard and that is what in my opinion caused her to go out of control and end up facing oncoming traffic."
He was satisfied the drivers of the other three cars involved, Aoife Boland, of Edgewood Lawns, Blanchardstown, Dublin, Brian Keoghan, of Slane Road, Navan, Co Meath and David Fox, of Woodlands, Portmarnock, were driving safely and were able to stop before the collisions occurred. He dismissed the claims against them.
In relation to the truck, driven by Krzystov Kopiczak, he said that the driver had "a grandstand view" of the vehicles in front and "should have been able to stop if paying attention and giving himself enough room from the vehicle in front".
He was satisfied Ms Ryan and the truck company were negligent.
The case was before him on appeal from the Circuit Court which found the truck company and Mr Fox were 50/50 liable.
Mr Fox appealed as did Ms Ryan against that court's decision dismissing her case against the MIBI.
He cut Ms Ryan's award by 25%, giving her €17,237 for which the truck firm is liable.