Drug-driving arrests leapt by more than a quarter across Suffolk in the two years since new legal limits came into force.

While detection of drug-driving rose, it fell for all other offences blamed for causing the highest number of deadly accidents.

Last year saw an almost 20% drop in the number of collisions causing death or serious injury on Suffolk’s roads, despite traffic levels hitting an all time high.

While police said overall safety camera enforcement had largely been maintained across the county, the number of Traffic Regulation Orders (TROs) issued for speeding fell 31% in 2017.

A road safety report showed TROs halved for mobile phone use and fell a fifth for failure to wear a seat belt, while drink-driving arrests dropped slightly – by 3%.

The paper said enforcement showed efforts had focussed more on drug-driving, as evidenced by decreases in the rest of the ‘Fatal Four’ offences.

Police have been unable to establish whether the figures meant more drivers taking drugs, or fewer speeding, using a mobile phone or not wearing a seat belt – but officers are now equipped to more easily detect drugs and secure prosecutions, which result in mandatory 12-month disqualifications for driving while over the limit for eight illegal and eight legal prescription substances.

The Road Casualty Reduction Team, comprising four officers on motorcycles, accounted for a large proportion of total enforcement across the force for speeding (32%), mobile phone use (49%) and seat belt infringements (68%).

Suffolk’s two average speed camera systems – on the Orwell Bridge and the A12 from East Bergholt to Stratford St Mary – caught 14% fewer speeding drivers last year; the two fixed camera sites – on the A12 at Benhall and A140 at Coddenham – caught 16% fewer speeders; and the county’s mobile safety camera vans caught 3% fewer speeders.

However, there was a significant 70% increase (from 3614 to 6154) in Community Enforcement Officer reports – now accounting for 19% of total enforcement – as resources are set to double to four full time equivalent posts.

Community Speed Watch schemes, run by volunteers and funded by local parish councils, are now active in 56 parts of the county – with the number of first and second warning letters sent to speeding drivers up year-on-year (6.5% and 26.7%).