But a large majority of Canberrans believe they can travel at least 5km/h above the speed limit without being fined.

"The majority of residents think that it is acceptable to travel over the posted speed limit (85 per cent), in a 60km/h zone, with the median acceptable speed (without receiving a fine) being 65km/h (5km/h over the limit)," the research found.

"The most common speed that residents think should be acceptable (without recording an offence), within a 100km/h zone, was 107km/h (7km/h over the limit). However, 87 per cent of residents thought that there should be some degree of tolerance toward speeding in a 100km/h zone."

Monash University's Accident Research Centre also found people thought the chances of getting caught in speeding in Canberra were reducing.

"While a similar number of residents reported that increasing the number of police on the road would improve driver behaviour, a higher percentage thought that the risk of being caught speeding was low (41 per cent) compared to 2013 (26 per cent), and that increasing penalties would not improve driver behaviour (59 per cent in 2018 compared to 28 per cent in 2013)."

Canberrans believed increased police patrols were more likely to get people to drive more safely than speed cameras.

"Similar to previous years' surveys, the majority of respondents strongly agreed that increasing the number of police patrols on the road would result in improved driver behaviour," the report said.

It also found in the 12 months up to September 2017 that fixed cameras and the Hindmarsh Drive point-to-point camera had lead to a 25 per cent drop in reported crashes.

Road Safety Minister Shane Rattenbury said there was a lot of community cynicism about speed cameras but the data showed they were working.

"We're not saying speed cameras are the only thing," Mr Rattenbury said.

"What this research does show is the cameras do make a material difference [and] are worth having out there."

The centre also estimated the mobile cameras alone had helped prevent 120 casualty crashes, where a person would be seriously injured or killed.

About 3000 road crashes had been avoided due to the mobile speed cameras, the report found.

It also found the mobile cameras had saved the ACT more than $60 million in property and health costs resulting from road crashes.

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The report follows an announcement by Mr Rattenbury to ban all L-platers and P-platers from making hands-free calls while driving, no matter when they got their license.

Belinda Clark, one of the report's authors and research fellow at the research centre, said the statisticians behind the report accounted for things like an uptake in cyclists, fewer drunk drivers and improved safety features on cars, which might result in fewer crashes.

"It's well established analysis ... it's a specialty area with the accident research centre," Ms Clark said.

She said the most simple way to explain the methodology was researchers looked at one section of road where road safety cameras operated, then compared it with sites of a similar nature where cameras hadn't been set up.

Mr Rattenbury also pointed to the report's survey of Canberra drivers, which found about 31 per cent of respondents aged 18 to 24 years old admitted to exceeding the speed limit by more than 10km/h. They were also the least like to support a "no tolerance" approach to speeding.

The survey also found 44 per cent of learner motorcyclists self-reported speeding 10km/h over the limit, as well as 36 per cent of P-plate motorcyclists.

But it can't be all pinned on the millennials, the survey found the majority of Canberrans - 85 per cent - thought it was acceptable to speed about 5km/h over the speed limit in 60km/h zones and 7km/h in 100km/h zones.

Those responses appeared to show Canberrans believed they would be permitted to speed without copping a ticket, the report said.

Fourteen per cent of Canberra drivers said they had been booked for speeding within the past two years, 73 per cent were detected only once in two years, 18 per cent twice and 8 per cent three or more times.

The majority of them, 69 per cent, resulted from mobile speed cameras.

Mobile speed cameras raised the government about $10 million in the 2018. Mr Rattenbury said two more road safety cameras are set to be introduced this year.

The cameras can detect speeds across six lanes of both oncoming and outgoing traffic depending where they were placed.