The warning comes after a crash on Learmonth Road in peak hour on Tuesday saw numerous drivers speed through the emergency area as crews worked to clean up the scene.

Wendouree Fire Brigade Lieutenant Chris Mair said she was shocked at the attitude of drivers, particularly those heading south towards Ballarat who ignored crews as they tried to slow them down.

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"It's something that most people are aware of, but the odd ones simply don't pay any respect," Lieutenant Mair said.

"The standard thing is a downward hand motion to slow down. I had one motorist who assumed we were waving at him, another woman gave us the dirtiest look as if to say 'how dare you hold me up?'

"It's incredibly frustrating and it's not just our brigade. Every brigade that attends any scene has the same issues."

Lieutenant Mair said often it felt like emergency services were not seen as human.

"It's as if they don't equate the fact that we also have families and we want to go home to as well," she said.

"It's our job to get things cleaned up so things can return to normal and make things safe. I'm sure you don't want to drive over debris and damage your vehicle."

The law, which came into effect on July 1, 2017 states that drivers must slow down to 40km/h when emergency vehicles have their flashing lights on.

The rule includes passing a vehicle on the opposite side of the road on a single carriageway road, but not if the road is divided, such as by a median strip on the Western Freeway.

Ballarat Highway Patrol's Acting Senior Sergeant Stuart Gale said it was a big issue that emergency services constantly had to deal with.

He said though there was a lack of compliance with marked police cars, there was even less with unmarked vehicles.

"It is slowly gaining traction but not enough," he said. "It continually needs to be revisited so people are aware."

"There has been enough publicity around it now and people should surely be aware that they should slow down when people are attending an incident on the side of the road."

Acting Senior Sergeant Gale said when pulling people over, people continued to use the excuse that they were not informed.

During the past two years, billboards and television campaigns have advertised that if a driver is passing a slow moving or stationary police, emergency, enforcement or escort vehicle with its lights flashing or sirens on, you must slow to 40km/h and not increase in speed until a safe distance from the scene.

A State Government spokesperson said it was up to drivers to follow the laws and mentioned that any possible changes to how the law was policed would only happen once drivers were fully aware of their responsibilities around emergency vehicles.

"This has been highly publicised for sometime now and drivers need to acknowledge they need to follow these sorts of laws," the spokesperson said.

"The law has been introduced with the intent of health and safety, it's there for the right reason. More members of the community need to understand why it is in place."