A WELSH motorway has been exposed as the most dangerous stretch in the UK for tailgating.
Drivers along the M4 in Wales are more likely than anywhere else to find other motorists driving dangerously close behind, according to the results of a survey by motoring organisations.
More than 50% of drivers on the road ventured too near to the car ahead of them, the study found.
The findings also showed more than a quarter of motorists were "an accident waiting to happen" because they drive too close to the vehicle in front on motorways.
Produced for the start of the August National Motorway Month campaign, more than 22,000 vehicles were surveyed earlier this summer by researchers from the Institute of Advanced Motorists (IAM) who fed data to the RAC Foundation for analysis.
The foundation, the IAM, the Freight Transport Association and BSM Driving Schools are jointly promoting National Motorway Month.
The organisation has highlighted tailgating as the number one driver error on the UK's motorway network.
Highways Agency research into safe driving found that tailgating contributed to 29% of all injury accidents on the network.
IAM chief examiner Peter Rodger said, "It's obvious that too many drivers simply forget their speed, regardless of the conditions on the motorway or what is in the lane ahead of them.
"They then follow other vehicles as if they were travelling much more slowly.
"So they are ignoring the two-second rule, designed to help you leave enough space between you and the vehicle in front so you can pull up safely if it suddenly slows down or stops."
The poll showed that the next-worst tailgating motorway was the M42 in the Midlands, followed by the M9 in Scotland.
The best motorway behaviour was found on the M5, where just one in 12 drivers were tailgating, followed by the M20 and the M2.
Despite being the safest roads in the country, there are still more than 8,000 drivers killed or seriously injured on the network each year.
More than 42% of crashes occur within 1km of a junction.
Mike Greene, from the West Wales Hauliers Association, said there was a huge problem on the motorway.
"It's crazy, some of the things you see.
"Drivers get angry and lose the plot.
"There's supposed to be a safe distance between vehicles for a reason.
"But a lot of car and van drivers seem to completely forget that.
"You can see they get angry, or they seem to be desperate to get ahead, and they totally ignore the idea of a stopping distance.
"As a lorry driver, you also find a lot of the time that you've left a safe distance between yourself and the vehicle in front, only for a car to whiz in the space in front of you.
"When you're carrying 24 or 25 tonnes of cargo, it's not exactly easy to stop quickly.
"But people get so wound up with the idea of getting in front, they forget they can be risking people's lives."
And he accused police of not doing enough to stop the problem.
Mr Greene added, "It seems like they're not really interested if it can't make them money.
"They're happy to put cameras up everywhere and rake it in from speeding fines, but they don't seem to be able to actually get out there and make roads any safer."
A spokesman for South Wales Police said, "Tailgating is extremely dangerous and can cause crashes with drivers losing concentration or becoming irritated due to other motorists' behaviour.
"It is recognised by motorists as the most annoying habit on our roads today.
"We would ask everyone to consider the two-second rule, which suggests that when driving in good dry conditions an observant driver needs to be at least two seconds from the car in front. The gap should increase if the weather or mechanical connotations change.
"We will continue to drive home the message of driving safely throughout the year and are committed to making the roads as safe as possible for all users."