More homes are urgently needed to address Australia's housing affordability crisis but without increased investment in public transport, new residents face increased congestion and worse standards of living, says an influential car lobby group.
The South Australian government has released enough land to build almost 25,000 homes, mainly on Adelaide's northern and southern fringes, in a bid to house an influx of new residents.
In a surprise intervention, the Royal Automobile Association of South Australia - who generally advocate for improved roads - are leading calls for an expansion of Adelaide's commuter rail system to connect new developments which would otherwise add further traffic congestion.
"There's no doubt we need more homes but we also want to see an investment in infrastructure to support this growth at the same time," RAA chief executive Nick Reade said.
"Housing developments can't outstrip infrastructure and utility investment - otherwise we're doomed to repeat the mistakes we've seen in Mount Barker where infrastructure is playing catch-up. "
The RAA estimates 100,000 more commuters could be added to Adelaide's roads as a result of the new developments.
"That puts more pressure on our road network, increases congestion and impacts the liveability of Adelaide - something we should never compromise on," Mr Reade said.
In 2023, less than six per cent of trips in Adelaide were made using public transport, lower than Sydney, Melbourne, Brisbane and Perth, according to the Bureau of Infrastructure and Transport Research Economics.
Despite South Australia's heavy reliance on cars, the state government has continued to funnel money into new road projects, including the $15.4 billion North-South Corridor, while funding for public transport languishes.
Transport Minister Tom Koutsantonis said proposed rail extensions to Aldinga in the south, Concordia in the northeast and a new line to the 12,000 home Riverlea development in the north were not yet justified but would be one day.
"It's no good building a billion dollars worth of rail line extensions if people aren't going to use it," he told reporters on Monday.
Rail and O-bahn patronage was yet to recover to pre-pandemic levels, so talk about rail extensions is premature, Mr Koutsantonis said.
He said the government had done work in protecting the rail corridor south to Aldinga so the land is available to build on when the time is right.
South Australia's full pipeline of infrastructure projects, as well as a shortage of skilled workers, stood in the way of immediate investments in rail infrastructure, Premier Peter Malinauskas said.
"These people are going to have to come from somewhere, so even if we committed to rail tomorrow, I don't even know if there'd be the latent capacity within the workforce to actually do it," he said.