Mr Clark and Springwood woman Sarah Frazer, 23, were killed on the Hume Highway last Wednesday when a passing truck hit them.

The 40-year-old father of four and owner of Highlander Towing had stopped to help Ms Frazer, whose car had broken down just south of Mittagong.

On Friday, fellow tow truck operator and friend of Mr Clark, Danny Whittaker of Penrith Towing, launched Highlander Move Over Law - Tow Truck Safety, a Facebook page announcing a nationwide call to arms.

The site campaigns for a law to make it mandatory for motorists to move over or slow down in the presence of amber flashing lights used by any operator who renders roadside assistance.

Similar laws operate in the United States and Canada, where failure to comply attracts fines of up to $1000.

“We are left to save ourselves and the people in these positions ... it is up to us now,’’ Mr Whittaker said.

He hoped to have the “move over’’ law established in Mr Clark’s name, to show his family “he did not leave us in vain”.

“Geoff’s death has sparked a bit of anger in me because we’re so ... alone and vulnerable out there.

“We’ve just got to pull up with our flashing lights on and that’s all we’re legally allowed to do.”

Highlander Towing truck driver Steven Smith said he worked with Mr Clark for the past five years.

Mr Smith said Mr Whittaker’s proposal to make drivers slow down when passing working tow trucks was “a damn good idea” because of the “extremely dangerous” nature of the job.

“Something needs to be done,” he said.

“Maybe we need some sort of electronic warning device like a flashing sign that we could put 100 metres up the road to warn traffic that a tow truck is in operation close by,” he said.

He said many tow trucks now used remote control to hoist a vehicle off the road, but first the vehicle needed to be secured manually, which proved dangerous when securing the right-hand side of the vehicle.