Pick a population number, throw it out there, get publicity.

That’s how it works in South Australia when business people want to create a debate about the size of our population. Of course, it’s completely debatable whether state government policy can substantially address the state’s rate of population growth, which continues to lag most other states despite various, mostly disjointed, efforts to make a difference.

In the past month, we’ve seen Business SA repeat its longstanding calls for fast-tracked growth and News Corp launch a campaign for an increased population, backed by a casino, an agribusiness company and an oil and gas company. As part of this push, new Committee for Adelaide chief executive Bruce Djité made a pitch for two million people in the state by 2030.

Bruce believes we have the necessary infrastructure – right now – to accommodate such a population.

The evidence suggests strongly that this assertion is wrong in several areas.

And this point is a key reason why business leaders continue to receive a lukewarm response to their growth agendas.

There are many questions that are almost always entirely ignored, or included as a subsidiary consideration when discussing growth – the impacts on social infrastructure and the environment among them.

But one of the most pressing is this: how, exactly, would South Australia’s transport infrastructure cope with accelerated population growth?

We have the worst public transport system of any major Australian city and a long-standing and heavy reliance on private vehicles.

Carving a multi-billion-dollar road from north to south – as we are doing now – will not improve log-jams on the South Eastern Freeway; it won’t make it easier for a Salisbury parent to get their child to school or childcare; it won’t help a Campbelltown teenager get to their part-time job; it won’t assist elderly South Australians, who no longer drive, to get to medical appointments or their local shops.

What we need – what we’ve desperately needed for many years – is a consensus approach to rebuilding a credible mass public transport system for Adelaide and connecting the city with the regions, not to mention fixing the chronic lack of public transport beyond greater Adelaide.

The state has no integrated or long-term vision for improving its woeful public transport – from either side of politics – and all evidence so far suggests that even the currently projected population increase, let alone accelerated growth, will lead to gridlock on key roads.

SA business leaders need to make this a priority in their growth lobbying, not just by adding some throw-away lines in the fine print, otherwise they are selling an unconvincing dream. Worse, if their aspirations come true in the absence of bold policy action, it will lead to a less liveable Adelaide.

The Committee for Adelaide, itself, made a “high level” submission to Infrastructure SA when it was developing its recent 20-year plan, arguing that the state needs a population growth strategy to address infrastructure needs.  “A greater focus will be needed on public transport to free up traffic congestion…,” the submission said, without adding any detail.

That was it.

Other business and developer groups are similar in their cursory, some would say glib, approach to this central issue.

They need to do better than that. Much better, if they want a sceptical public to climb on board the growth train. There are strong arguments for developers to help shoulder the cost burden of public infrastructure required by their ventures: if that’s a bridge too far, the least they can do is become fiercer, more informed, advocates for government action.

The consequences of continuing our directionless doddle will be severe.

Consider these key points from transport modelling for Adelaide, produced for Infrastructure Australia in 2019 (the modelling even factors in a slight shift to public transport from private cars which, post-pandemic, seems unlikely):

• By 2031, peak congestion on Adelaide’s roads will increase “significantly”, with inner-city and some suburban road networks under pressure.
• “Heavy congestion is forecast both on the South Eastern Freeway itself as well as onto the arterials it connects with.”
• “Average vehicle speeds on the road network are expected to decline by approximately five kilometres per hour in the AM and PM peak periods.”
• By 2031: “Access to education infrastructure is likely to be more difficult without access to a car.”
• The South-Eastern Highway/Glen Osmond Rd Corridor is forecast to be one of the worst-performing in Adelaide.
• By 2031 Adelaide’s motorists can expect longer traffic delays, with drivers expected to spend a higher proportion of their journeys stuck in traffic. The Fullarton Road and Goodwood Road corridors are expected to be among the worst for delays.
• It’s also not going to be fun on public transport services: “The demand placed on Adelaide’s north-south rail and bus corridors is expected to increase significantly due to population growth in Adelaide’s northern suburbs. By 2031 crowding on the Gawler Line is forecast to worsen substantially with passenger volumes near the capacity of trains.”

Beyond the city limits, the situation is arguably worse. An independent analysis commissioned by Bus SA released last week shows that South Australia’s regions lack even the most basic regular and accessible bus services. South Australia’s per capita spend on regional public transport is tiny compared to others states: $40 per head here, compared to $439 in NSW and $133 in the giant expanses of regional WA.

The final dot point above highlights the challenge we face, given the reluctance of any political party to bring Adelaide’s archaic public transport system into the 21st century. Labor’s light rail plan at the 2018 election was at least something, but it’s unlikely the party will return to that expensive and bold policy.

The Liberals are ponderously continuing the long-awaited electrification of the Gawler line and have worked on some other small rail projects, but its major public transport effort this term was an abandoned attempt to reshape bus services, mostly by reducing the number of stops. The public rejected it and for good reason.

No other major Australian city has such a poorly connected public transport system. No other Australian city has such a relatively tiny rail network – both heavy and light. We are even lagging behind on basic stuff like bus priority lanes. Any transport planner will tell you this: only an efficient, mass public transport system can fix the looming problems.

Even without the acceleration in population growth hoped for by our business community, if our obsession with private vehicles continues, congestion will still choke our complacent city.

It is inevitable. We’re already experiencing it and the car-centric solutions so far have been very damaging to local communities. “Congestion busting” intersection widening projects are starting to rip holes in the urban fabric.

A debate about population is important.

But no call for accelerated growth is credible without an evidence-based prescription for how the basic functioning of our city will be developed in line with that growth.

Lobbyists for population growth need to start pushing governments for rapid and urgent improvements to public transport infrastructure, at the very least.

It’s a matter of equity but, unless significant action is taken soon, it will affect everyone’s lives: from the car-less pensioner to the chauffeured politician.

David Washington is editorial director of Solstice Media, publisher of InDaily.