The RAC says a crash that left a 42-year-old tow truck driver fighting for life shows the need for "slow down, move over" laws in WA.

About 1.40am yesterday, the driver was loading a broken-down taxi on to his truck from the emergency lane on Kwinana Freeway when a silver Dodge Nitro hit him.

He had life-threatening injuries and was taken to Fiona Stanley Hospital, then transferred to the trauma unit at Royal Perth Hospital, where he was in critical condition but stable last night.

The incident prompted the RAC to again push for debate on road rules that would require drivers to slow down and move over when they see first responders at a crash.

Such laws in NSW and the US force motorists to reduce speed by at least 30km/h when approaching a breakdown or crash.

RAC general manager corporate affairs Will Golsby said the issue was not just about road safety but also about the workplace safety of tow-truck drivers and other emergency responders including police, paramedics and firefighters.

Operations manager at AAAC Towing, Adrian Di Lallo, said by all accounts the driver "was just doing his job" and the crash highlighted the need for regulations around the operation of a tow truck.

In December 2013, tow truck driver Abby Hall was killed when she was struck as she worked on Roe Highway, Beckenham.

Last year the WA Police Union endorsed a motion at its conference to support the slow-down campaign.

Mr Di Lallo and Mr Golsby agree there needs to be a change in driver attitudes around breakdown and crash scenes.

"This comes down to behaviour when they see people at the emergency breakdown situation - slow down, drive sensibly, move over sensibly so people at the breakdown can get the community moving," Mr Golsby said.

"Drivers have a responsibility and it is a workplace safety issue."

The New Zealand-based family of the injured driver were last night on their way to Perth.

His employer McCallum Towing said he was a "top bloke, who always tries to make us laugh when he loads cars from the yard".

"Always there when you need him . . . can't wait to see him so we can make him laugh," the company wrote online.

Anyone who saw the Dodge Nitro before the crash or witnessed the incident is asked to call Crime Stoppers on 1800 333 000.