Mr Turnbull visited the site last Wednesday with Swan MHR Steve Irons and Finance Minister Mathias Cormann.
“I can see the need for it – to come off Manning Road and head south is quite an elaborate exercise,” Mr Turnbull said.
“There quite clearly should be an on-ramp.”
Get in front of tomorrow's news for FREE
Journalism for the curious Australian across politics, business, culture and opinion.
READ NOWMr Irons started campaigning for a south-bound on-ramp in 2009 after consultation with residents in the area.
“Now Fiona Stanley Hospital has opened, more and more people are travelling south on the freeway and an on-ramp would make a major contribution as productive infrastructure to the area,” Mr Irons said.
At present, there is no connecting ramp for vehicles wanting to travel south-bound on the Kwinana Freeway from Manning Road.
“Instead, vehicles travelling south must head north and negotiate a challenging stretch of road, doing a loop over the freeway involving merging and lane-changing,” Mr Irons said.
“The result is congestion, journey delays and dangerous conditions for drivers, as well as inconvenience in local residential areas, which are used as rat-runs to avoid the dangerous stretch of road.”