Will simply building more public transport seriously suppress car use?

But if the objective of policy is to effect significant mode shift (e.g. where, say, public transport at least has a larger share than cars across all trip purposes), much stronger policies that actively suppress the competitiveness of private vehicles relative to public transport will be required (see also What drives higher public transport use?).

In fact, unless we're prepared to take road space and traffic light priority away from cars so that buses and trams aren't caught in traffic, it's doubtful Australian cities can achieve even a modest increase in the mode share of public transport.

And don't get carried away by the mode shift potential of higher densities either. A study of US cities by Giles Duranton and Matthew Turner finds that a 10% increase in residential and job density would on average produce only a 1% reduction in driving.

Mr Turnbull is right to talk about investment in public transport and changes in land use. But it's nowhere near enough; he should go beyond rhetoric and actively push policies, like those recommended by Infrastructure Australia (e.g. 5.3 – 5.7), that directly address the key underlying problems, especially cars.