Perth motorists would save 73 hours a year - the equivalent of nearly two weeks annual leave - if traffic congestion was cut in half, a report to be released today has found.
The report by economic consultants Synergies also found the most cost effective way to dramatically cut congestion was through public transport.
"To halve Perth's current traffic congestion by investing in roads, $40 billion and 2000km of road lanes would be required," it said.
"To achieve the same congestion reduction with rail, a $25 billion investment would be needed.
"Halving Perth's congestion through rail investment would remove 163,000 cars from its roads during every peak hour."
The report, commissioned by lobby group Australasian Railway Association, said Perth commuters lost 14 million hours a year stuck in traffic. This meant a loss in productivity and leisure time.
"The detrimental impact of congestion on the livability of our cities is well known," the report said. "More importantly, it reduces productivity.
"Alleviating congestion by investing in public transport is therefore imperative to ensuring productivity growth, because it is the most efficient way to connect people with jobs in high productivity nodes.
"If no action is taken to invest in public transport, by 2031 the cost of congestion is expected to reach $3.8 billion per annum in Perth.
"Most importantly, it will retard productivity, which is fundamental to the economic health of not only our cities but also the nation."
The report's release comes just days after _The Weekend West _reported that - for the first time - licensed cars and wagons in WA had exceeded two million.
The Department of Transport data also showed there were an extra 200 cars and wagons on WA roads every day.
Curtin University's sustainability professor Peter Newman said the only way for Perth to avoid "carmageddon" - with its worsening congestion and a road system unable to cope - was to provide good public transport and cycling.
Shadow transport minister Ken Travers said the Synergies report highlighted the massive economic and social cost of the Barnett Government's chaotic transport planning.
He said investment in public transport should be a priority ahead of "monument projects" and Premier Colin Barnett's legacy would be massive debt and the costs of congestion.