South-west police road safety adviser Acting Senior Sergeant Simon Bourke said extra visitors were expected to flock to the Great Ocean Road, the Grampians and south-west coast cities and towns during the next few days.

Operation Amity will run from midnight Friday until midnight next Tuesday, with the statewide aim of high visibility police units targeting impaired driving (alcohol and drugs) and excessive speed as well as the other 'fatal five' causes of road trauma - driver distraction, fatigue and seatbelts.

Acting Senior Sergeant Bourke urged all south-west residents and visitors to be extra vigilant while travelling.

"Many visitors will be unfamiliar with our roads and will be driving long distances," he said.

"If you're driving far over the holiday period, please take time to rest and have regular breaks.

"It's better to make it late than not make it at all."

Acting Senior Sergeant Bourke said there had been incidents of dangerous driving on the Hamilton Highway during the past week and main roads would also be a focus this weekend.

A suburban Melbourne man was caught near Darlington with a blood alcohol level of .232 earlier this week and had to be intercepted by an off-duty Bendigo police officer due to the extreme manner of the man's erratic driving.

The man in his 50s was driving onto the wrong side of the road forcing other motorists to take evasive action to avoid collisions.

The road safety adviser also warned drivers police would be strongly enforcing reduced speed zones at road works.

On Tuesday this week a concerned motorist reported erratic driving near Mortlake, which led to the arrest of a 30-year-old Mortlake man.

The driver rang triple zero (000) on Tuesday morning and the offender was pulled over on the Hamilton Highway near Mortlake.

Operation Amity will target impaired driving (alcohol and drugs) , speeding, fatigue and mobile phone use.

Acting Assistant Commissioner John Fitzpatrick said regional Victoria remained a high risk for road trauma, given the increased speeds, longer distances travelled and influx of visitors.

He said police would be breath and drug testing across the unofficial long weekend at every opportunity.

Over the same time period last year Victoria Police caught 233 drink drivers and 141 drug drivers statewide.

Mr Fitzpatrick said out of the six deaths on Victorian roads this year, early indicationswere three of those people did not have a seatbelt on.

He said drivers were reminded about the importance of buckling up.

Operation Amity involves all available personnel from local road policing units to general duties and centralised support from other operational policing units.

"We know that people will be travelling to holiday destinations, and with this comes more traffic on our rural roads," he said.

"If you're driving long distances, take regular breaks and where possible share the driving to avoid fatigue.

"If you're having a few drinks with your mates, make sure you've planned how to get home without driving.

"We want people to have a good time, but do not want to be attending collision scenes where drugs or alcohol is a contributing factor."

Mr Fitzpatrick said putting on a seatbelt gave all drivers the best chance of survival if they were involved in a serious collision.

"Sadly, lives could have been saved if people managed to do this simple task," he said.

"Whether you are travelling a short distance down the road or on a long journey - always wear a seatbelt. There's no excuse..

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