Dedicated bus lanes - a centrepiece of the State Government's public transport strategy for the next 20 years - could be contributing to Perth's traffic congestion woes.
Research conducted for Main Roads and other Australian transport and traffic authorities has found some bus lanes have an adverse impact on other road users.
While dedicated lanes allowed buses to queue-jump and avoid congestion, they could add to delays facing the motorists they were overtaking.
According to the State Government's public transport strategy, released last year by Transport Minister Troy Buswell, Perth has 29km of priority bus lanes.
But it says more bus lanes will be needed to connect major centres and cut through congested intersections.
"Bus routes will be designed to maximise accessibility, whilst maintaining travel speed and ride comfort," the strategy says.
"Buses will take advantage of bus priority infrastructure to move through congestion and maintain on-time running."
The new research by Austroads, the body representing all Australian road authorities, identified three bus priority lanes:
·Full bus lane: A whole lane is dedicated to buses, an example being South Street in Leeming between Kwinana Freeway and Vahland Avenue.
·Set-back bus lane: Provides a dedicated lane between, but not including, intersections. An example is Beaufort Street in Bedford between Salisbury and Sixth avenues.
·Queue-jump bus lane: Allows buses to avoid congestion at intersections, with dedicated lanes and bus signals. An example is the intersection of James and Fitzgerald streets in Northbridge.
The report said full and set-back bus lanes resulted in low and reliable bus times but had an adverse impact on car travel time because of the reduced road space available for motorists.
It said dedicated lanes that allowed buses to bypass traffic queues could mean a substantial time saving for buses and their passengers, but this was offset by "additional delay to the vehicles which have been overtaken".
The report said finding a balance between the various road users was a particular challenge in the introduction of a bus priority scheme.
Mr Buswell said this week that Main Roads would continue to use a mix of the types of bus lanes mentioned in the Austroads report.