Pedestrians who walk on motorways are putting their lives at risk, road safety chiefs warned today.
They also said that motorists who stop on the country's fastest roads are in danger of causing a fatal crash or pile-up.
Figures show more than 100 people have been killed or seriously injured on motorways since 2005.
Eight people died last year, including four who had been walking on a motorway, with six people killed in collisions so far this year.
Noel Brett, of the Road Safety Authority (RSA), said: "The message is clear: never, ever walk on a motorway.
"Pedestrians are at a massive risk on a motorway - you're taking your life in your hands and putting other road users in danger too.
"Likewise, drivers who stop on a motorway can cause collisions involving their own car and potentially many others. It's unsafe and it's an offence."
The RSA, gardai, National Roads Authority and AA Ireland joined forces for a new safety campaign which centres on a 40-second television advert on motorway safety.
It focuses on lane merging, lane discipline, overtaking, what to do if your vehicle breaks down and tells the public never to walk on any of Ireland's 1,187km of motorway.
The AA also issued the message that drivers should respect the hard shoulder.
Conor Faughnan, director of policy, warned the hard shoulder was an extremely dangerous place to be.
"Some drivers use it almost casually," he said.
"In darkness or in foggy conditions the danger is magnified, and drivers need to be aware of it."
Chief Superintendent Gabriel McIntyre, head of the Garda National Traffic Bureau, said his officers had seen too frequently the carnage that results from reckless and dangerous driving.
"Families, friends, colleagues and neighbours have suffered grief and anguish, and the survivors of these collisions face their own personal battle as they struggle with the effects of their injuries on their lives and the lives of those around them," he added
"All road users should be conscious of the dangers posed by motorways and take heed of the advice - motorways are not for pedestrians and drivers should never stop on a motorway."