The number of dedicated traffic police officers in Northern Ireland has fallen by almost 40% in the last decade.
Currently there are around 150 such officers here - down from 250 in 2007.
Across the UK the number of dedicated traffic officers dropped by nearly a third, an investigation found.
It led experts to question how newer laws, such as the ban on using mobile phones while driving, can be enforced with 30% fewer officers dedicated to policing roads.
The figures emerged after Freedom of Information requests were sent to every UK police force asking how many dedicated traffic officers they have compared with five and 10 years ago.
The results reveal cuts have accelerated in the past five years, with numbers falling 24% since 2012, while overall the number is down 30% since 2007.
In 2007 there were 3,766 traffic officers in the forces which responded. In 2012, that figure stood at 3,472. By 2017 it had dropped to 2,643.
Some forces increased the number of traffic officers between 2007 and 2012, but as budget cuts hit these numbers were reduced between 2012 and 2017.
In Northern Ireland there was a 39% drop from the 249 dedicated traffic officers in 2007. By 2012 this number had fallen to 190, and has now slumped to 151.
Motoring organisation the AA said the decline could see more drivers getting away with crimes. A spokesman said: "We need more cops in cars, not fewer.
"The UK has among the safest roads in Europe, although the number of people killed and seriously injured on our roads has started to rise after many years of steady decline. Maybe there is a link."
He added: "Even senior officers have publicly expressed concern at the falling number of their colleagues."
Commenting on the Northern Ireland figures, Assistant Chief Constable Barbara Gray from the PSNI's Road Policing Unit said officers were determined to keep people safe.
"It has been well documented that policing numbers in general have reduced considerably over the past number of years, and the PSNI's Road Policing Unit has felt the impact of this reduction too," she added.
"However, with the advancement of digital technology, fixed and mobile speed cameras and greater partnership working, the public should feel reassured that policing our roads remains a high priority for the PSNI. Officers in other policing teams are also trained in specialist road policing equipment and detect traffic offences daily.
"We have also recently completed a recruitment exercise to appoint additional road policing officers to the unit.
"We all have a responsibility to keep people safe on our roads."
In total, 30 police forces across the UK released figures.
Of the rest, 11 did not hold data for the full 10 years and three had merged traffic into tri-force operations.
Labour's shadow minister for policing and crime, Louise Haigh, a former special constable, said: "These savage cuts will deeply alarm the public as reckless drivers will feel able to offend with impunity."
Jason Wakeford, from road safety charity Brake, said: "On average, five people die every single day on our roads. This is unacceptable.
"The Government and police forces have to start treating road policing as a national priority and reverse the savage cuts to officer numbers."
However, West Mercia Chief Constable Anthony Bangham, who speaks on roads policing for the National Police Chiefs Council, said: "Individual police forces decide how best to allocate resources and keep their communities safe.
"Some may choose to reduce the numbers of specialist traffic officers, but this does not mean that their roads are not adequately policed.
"They can deploy a range of resources, including ANPR (automatic number plate recognition) technology, targeted patrols using unmarked vans, high vantage points and helmet cams to catch offenders.
"All police officers are available to help those who are traffic policing specialists."