Alcohol and drug testing has been a feature of road safety enforcement for decades. Roadside Breath Testing (RBT) was introduced more than 40 years ago and is today delivered through both car and bus operations while Roadside Drug Testing (RDT) was introduced in 2004 through a similar model to address the increased rate of drug driving.

The Monash University Accident Research Centre (MUARC) recently released research about the role drugs are playing in the state's road trauma, predominantly based on data for the decade from 2006 until 2016.

It found that while THC (cannabis) was the most common drug detected in drivers involved in fatality and serious injury crashes in the earlier years, since 2013 methamphetamine (more commonly known as 'meth' or 'ice') has become more prevalent.

According to the most recent data, 18 per cent of drivers had ice in their system when they were killed - equivalent to one in five drivers. The drug was also present in about 4.3 per cent of crashes where a driver was seriously injured.

By comparison, 16 per cent of drivers had cannabis in their systems when they were killed, while 2.5 per cent had the drug in their systems when they were seriously injured.

In all, illicit drugs were detected in around 25 per cent of drivers killed on the state's roads.

Additionally, alcohol also continues to contribute to trauma - it was a factor in around 17 per cent of fatal crashes, with more than two thirds returning high range readings.

It was also detected in around 5 percent of drivers who were seriously injured, with around half returning a high range reading.

In the past five years the trend has continued - 18 per cent of drivers had illegal blood alcohol levels while 41 per cent had drugs, both legal and illegal, in their system.

As part of the project, the researchers analysed different testing rates in police regions across the state.

Professor Max Cameron (researcher) said while contrary to the law, only about a third of drivers admitted to hospital were tested for drug or alcohol.

This means much of the data in the study is believed to be lower than the reality - he estimated the serious injury rates could in fact be up to three times higher.

In the Ballarat region, however, drivers transported to hospital are much more likely to have a blood sample taken.

As a result of this high rate of drug and alcohol testing he said the presence of ice recorded was much higher in this region than other areas across the state.

Of those tested in the western region in 2016 almost 15 per cent tested positive for ice while 8.5 per cent tested positive for cannabis, Professor Cameron said.

Victoria Police use both general and specific deterrence approaches to reduce impaired driving and road trauma.

Ballarat Highway Patrol Senior Sergeant, Stuart Gale, said impairment factoring into trauma in the region had not increased dramatically during the past few years. However, drugs had overtaken alcohol as factors in the region's trauma.

COVID has tipped the scales a little, with police recently noticing an increase in drink driving.

With intercepts generally made as a result of driver behaviour, he said impairment was easy to detect and even easier at night when there were less cars on the roads.

Senior Sergeant Gale said driving while impaired - whether alcohol or drugs - were significant factors in the region's road trauma, along with fatigue and inattention.

"You are driving a vehicle and you shouldn't be impaired in any way, shape or form. It's a big enough task driving a vehicle and having due care and attention.

"People need to wake up. I think people think it's their right to have a licence and they get behind the wheel and forget about their obligations to themselves, their passengers and other road users."

As of May 6, police had conducted more than 105,000 roadside drug tests in the 2020-2021 financial year. The force is on track to deliver 150,000 by the end of the year.

A spokesperson said expanding roadside drug testing to one member stations in some rural areas, including north of Ballarat, was "very successful" and was now being undertaken in an ongoing capacity.

"Further trials are currently under way at larger rural police stations as an opportunity to refine the roadside drug testing model and provide greater roadside drug testing capacity and coverage."

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They added the force had "significantly boosted" the number of police trained as a Drug Impairment Assessor's (DIA) to ensure drivers are detected and prosecuted.

"This offence carries a gaol sentence of up to 3 months for a first offence and up to 18 months for subsequent offending."

The first of its kind, the research included an in-depth analysis of the effectiveness of the increase in roadside drug tests from 42,000 in 2015 to 100,000 per year from 2017 onwards.

The increase had prevented more than 33 fatalities and nearly 80 serious injuries on Victorian roads each year from 2016-2018.

Further, it reveals the increase in roadside drug tests to 150,000 during 2018-19 should have prevented a further 23 fatal crashes and nearly 56 serious injury crashes.

The researchers advocate for further increases in roadside drug and alcohol tests given their effectiveness and the foreseen prevention of fatality and serious injury crashes.

Professor Cameron described roadside drug testing as a "very important" part of the road safety response.

"Roadside drug testing is more expensive than alcohol testing but the report shows it's still well and truly worth the investment.

"The amount of testing could be tripled without any problem."

To address drug driving, a high number of tests should be conducted but predominantly from cars.

Random testing can be implemented to target cannabis use but police should preference testing in areas where crashes have been linked to cannabis. This should predominantly be during the night.

To address drink driving, the researchers recommend delivering "a large number of tests from both car and bus operations" during "high alcohol times" - mostly at night - and in areas where the issue is prevalent.

While cannabis is a more social drug, he said ice was "very impairing and addictive".

This is made clear through recent research from the Victorian Institute of Forensic Medicine that found the relative risk associated with cannabis was 1.9 - about the same as a person who has been drinking and who has a BAC of .05.

But the story is completely different with ice.

"The relative risk of that is about 19 - about 10 times the relative risk associated with THC," Professor Cameron said.

For ice, enforcement should also involve a high number of tests, though not randomly as ice impaired drivers were found to get behind the wheel around the clock, thus to be effective testing needed to take place as much as possible and throughout the day.

Professor Cameron said this particular finding about ice was new.

"We've known for many years about high alcohol hours and THC is very similar but methamphetamine is a 24/7 problem on the road," he said.

With no tools like an alcohol interlock that can be installed, Professor Cameron said a different approach needed to be taken.

"Ice users are so addicted so it's difficult to keep them off the road. You've not only got to detect them on the road but you need programs that address the addiction," he said, adding this was needed from a health perspective.

"It makes it very difficult for police to target specific times of the week in targeted operations because they need to do it as often as they can on as many days as they can."

The Transport Accident Commission said the report reinforced the critical role enforcement played in keeping Victorians safe on the roads and why investment in testing was vital to reach the Victorian Road Safety Strategy's ambitious target to halve road deaths and reduce serious injuries by 2030.

Enforcement is one of the strategy's six focus areas, and will cement a further increase in drug testing every year - deterring people who choose to take drugs and drive - as well as the introduction of new laws and penalties to remove dangerous risk-takers from the roads swiftly.

TAC acting chief executive, Liz Cairns, said the organisation had long recognised the "critical role" enforcement played in road safety and would continue to support police to remove drug drivers from the roads.

Acting Minister for Police, Danny Pearson, agreed.

"We make no apologies for being tough on drug-drivers - and Victoria Police will continue to work with our road safety agency partners to take dangerous drug-affected drivers off our roads."