Wire rope barriers will be installed along unprotected parts of Kwinana Freeway after months of campaigning by the family of crash victim Julian Murphy.
The 32-year-old was killed on April 24 when Ronald Frank Weston, 79, lost control of his Toyota Camry on the freeway and crossed from the southbound to the northbound lanes.
The bush median strip failed to stop the car, which crashed into Mr Murphy's BMW, killing him.
Mr Weston pleaded guilty last month to dangerous driving causing death.
Four months later, Luke Wales, 28, died when a Toyota Avensis driven by Glenn Griffiths Carter, 56, crossed the bush median strip on Roe Highway and hit his Nissan Pathfinder. Mr Carter also died in the crash.
Kevin Murphy said yesterday his son "had less than no chance" and that all three deaths were preventable.
Though the grief and pain of his loss haunted him every day, Mr Murphy had dedicated himself to preventing further tragedy on high-speed roads.
Now his campaign is paying off, with Main Roads and the Office of Road Safety confirming a commitment to install wire rope barriers on sections of Kwinana Freeway divided only by bush.
The cables, already used on some sections, can stop vehicles crossing into oncoming traffic.
Mr Murphy said the commitment was a step in the right direction and showed both organisations identified the need for a program to reduce similar accidents.
A Main Roads spokeswoman said barrier design for the freeway from Thomas Road to Safety Bay Road would begin next year, with funding expected from the road trauma trust account.
Mr Murphy, wife Mary, son Stefan and grandson Thomas joined 200 of Julian's friends yesterday at a memorial Twenty20 cricket match between North Fremantle Football Club and Melville Cricket Club. Julian was heavily involved in both.
A commemorative plaque was unveiled and will take pride of place in the cricket club's bar.
Mr Murphy said only after his death did the full extent of his son's kind and generous nature - including mentoring those in need of it - shine through.
"So much has come out about him because he never really talked about things, he just went and made them happen," he said.
"He was very much a people person, whether at work or in his personal life. He had a very kind heart and he was very insightful at looking at a problem and looking at a person and working out what needed to happen."
Now the family hope Weston's sentencing next month will close another chapter.
Mr Murphy said he did not expect Weston to be jailed because of his age. But he hoped his licence would be revoked and for senior driving laws in WA to be examined.
In April last year, Transport Minister Troy Buswell scrapped compulsory medical checks for drivers aged 75 and 78. Drivers aged 80 must have medical checks and after 85, they also need an annual driving test.
Mr Buswell said at the time the Government did not want to "retain outdated regulations that are potentially bad on misconceptions or stereotypes".
Yesterday, he said it was important to monitor road safety research continually and ensure regulations were consistent with current evidence.
Mandatory reporting of medical conditions or driving impairments for all licence holders had proved to be the best way to identify all drivers who were potentially high-risk.
Council for the Ageing WA chief executive Ken Marston said Mr Murphy's death was terrible but it was wrong to home in on the competence of older drivers.
He said five-year averages showed drivers aged 25 to 29 were involved in 30 per cent of serious crashes, compared with 6 per cent of drivers aged 70 and over.