A tunnel as part of the controversial Perth Freight Link will reduce road deaths, increase house values and create more jobs, a study has found, but the opposition has rejected the findings.
The report, prepared by Matusik Property Insights, found the tunnel was likely to have a greater positive effect on residential values than improving surface traffic routes.
Transport Minister Dean Nalder admitted he was surprised about the potential uplift in residential values over the long term, which could be up to 86 per cent.
But the report stresses current local end prices, which are high when compared to the Perth average, might not rise as much as the findings suggest.
"All of our case studies are based on infrastructure provision, which took place many years ago at a time when end price points were more affordable than today," the report read.
Mr Nalder said it was important to note a potential drop in the number of road fatalities by up to 70 per cent.
"Since announcing Roe 8, we have consistently said it would reduce congestion and make our roads safer," he said.
"The evidence of other similar road projects proves that with reduced congestion, the roads are safer and there are fewer fatalities."
But opposition transport spokeswoman Rita Saffioti has rejected the analysis.
"I'm not sure how a Queensland property consultant can tell me how many road fatalities are going to happen in WA," she told reporters.
Ms Saffioti said it was merely another attempt from the state government to try to justify the flawed project.
The $1.9 billion project, mostly funded by the federal government, will provide a more direct route to Fremantle port for trucks and is the largest road infrastructure development of its kind ever undertaken in WA.