Mode share of motorised travel for five largest Australian cities, public transport vs private transport (source data: BITRE)
Not much to cheer about here – mode share of motorised travel (passenger kms) 1945-2014 for five largest Australian cities, public transport vs private transport (source data: BITRE)

Malcolm Turnbull should take a look at the exhibit above; it shows that public transport’s share of motorised travel in Australia’a five largest capital cities has been depressingly low for decades, while private travel (essentially cars) continues to dominate.

There’ve been some small blips but there’s no dramatic improvement notwithstanding the well publicised drop in per capita driving and, just the other week, a report that over-eighties are now more likely to drive than millennials aged 18-24 years.

Quite simply, public transport isn’t even coming close to winning the “fight” with the car. Back in 2002, Melbourne’s strategic plan set a target of 20% mode share for public transport by 2020. There was a well-publicised patronage surge over 2006-09 due mainly to unprecedented CBD jobs growth, but mode share stabilised since then at just 11%.

Mode share

I noted recently that simply building more mega public transport projects won’t, by itself, be enough to seriously improve public transport’s mode share (see Will politicians ever do anything real about cars in cities?).

That proposition probably sounds counter-intuitive and demands further explanation. So consider the impact the following proposed major rail projects would have on car use if and when they’re completed (1).

Sydney CBD and South East light rail: This 12 km line is estimated to cost $2.1 Billion however 75% of forecast patronage will come from existing bus users. It’s anticipated existing motorists will account for only 17% of users (see Is Sydney’s new light rail line about saving the planet?).

Doncaster Hill rail extension: The Victorian Government’s feasibility study for the proposed $4 – 6 Billion rail line in middle suburban Melbourne concluded that 98% of forecast patronage on the line would be diverted from existing public transport services (see Would a rail line to Doncaster really get cars off the freeway?).

Rowville rail extension: The proposed 12 km rail extension to Rowville in outer suburban Melbourne is likely to cost something like $3 Billion but the Government’s feasibility study found it would reduce the number of car trips on a typical weekday in 2046 by just 15,000; that’s trivial in the context of the circa 12,000,000 trips Melburnians currently make by car each day.

The study also concluded it would increase the share of all trips carried by public transport in the metropolitan area in 2046 from 12.6% to just 12.7% i.e. by 0.1% (see Do new suburban rail lines always make sense?).

Melbourne Metro: The latest estimate of the cost to build the planned 9 km tunnel under the CBD is $11 Billion. According to the Government, the project will provide capacity for an extra 39,000 passengers across the CBD during the peak. That’s a significant increase in CBD peak capacity (it’s bigger than the Westgate Bridge) and there’ll be network-wide benefits in terms of greater reliability. So it’s worth doing. (2)

But it’s the veritable drop in the bucket in terms of generating mode shift given the size of the total metropolitan transport task.

Although I don’t have formal mode change estimates, the proposed $2 – 3 Billion Melbourne Airport rail line would replace the existing SkyBus (note Brisbane’s established Airtrain has just 8% mode share). Brisbane’s proposed $5.5 Billion Cross River rail line, like Melbourne Metro, is aimed at increasing peak capacity through the CBD.

Why small impact?

My point isn’t to deny the benefits mega projects bring to public transport users; most of the current raft of rail projects touted by State Governments are worthwhile improvements. Rather, it’s to point out that even very costly rail projects – and this group collectively would cost $25-30 Billion – won’t by themselves have a big impact on car use.

Why would so much money have such a small impact on mode split?

In part it’s because most new rail projects serve work trips to the CBD, where congestion and high parking charges mean public transport’s mode share is already very high e.g. 80% of motorised trips in Sydney.

Most importantly though, it’s because Australia’s capital cities are highly suburbanised; more than 90% of the population and around 70% of jobs are more than 5 km from the CBD. Moreover, only around 20% of trips are for the purpose of getting to work.

Even shiny new rail lines can’t compete well with the car for local and relatively short trips in the suburbs e.g. for shopping, personal business, school.

Given the breath-taking cost of retro-fitting rail it’s implausible to suggest that low density Australian cities can effect a significant shift away from driving just by building more and more public transport infrastructure.

Nevertheless, while they wouldn’t look much like the Paris Metro, Australian cities can and should have modest but effective metro-style systems that work with our low density cities. These would be based largely on existing train lines networked with a “grid” of frequent bus/light rail services operating with priority in existing road space. (3)

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 no where near enough; he should go beyond rhetoric and actively push policies, like those recommended yesterday by Infrastructure Australia (e.g. 5.3 – 5.7), that directly address the key underlying problems, especially cars.


  1. I’ve selected these examples because the necessary data on future patronage is available publicly. Note that while Melbourne Metro and Sydney CBD and South East light rail projects are commitments, the Doncaster and Rowville rail projects remain long terms plans
  2. Update: the business case for Melbourne Metro released on 23 February shows the new line will have capacity for 12,000 passengers in the two hour peak; but it will “enable” additional capacity in other lines, providing a further 27,000 passenger capacity in the CBD in the peak.
  3. Public transport can win a bigger share in some locations like the inner city where density works organically to make driving less competitive, but note that in all capital cities less than 10% of residents live within 5 km radius of the CBD (which happens to be around the same area served by the Paris Metro).