The Adelaide Hills town of Mount Barker is undergoing a population explosion, and that's on track to continue over the next decade.
The big issue for locals has long been infrastructure — especially transport corridors connecting the emerging peri-urban centre with Adelaide's CBD about 30 kilometres away.
One option is, and has long been, a railway line.
There have been rumblings for years, and while talk of trains has not quite been smoke and mirrors, it's fair to say there's been a lot of hot air.
But a Spanish company is about to embark on what is potentially the most significant step yet towards getting trains back to Mount Barker.
What's the proposal?
During the recent election campaign, Labor committed to undertake a review of the viability of restoring commuter rail services to Mount Barker, after an almost 40-year hiatus.
Adelaide Metro's current Adelaide Hills line ends in Belair, but the parallel freight line — which runs all the way to Melbourne, and is managed by the Australian Rail Track Corporation (ARTC) — extends a branch line to Mount Barker.
That line hasn't been used for passenger services to the city since 1984.
Spanish train manufacturer Talgo yesterday issued a letter to the SA government asking for its support for a high-speed passenger train trial.
After preliminary assessments, the company has estimated its train could complete the "Adelaide to Mount Barker trip in around 45 to 50 minutes".
"We're very serious, Talgo is very serious," consultant Luigi Rossi said yesterday.
"As part of that ... we undertake a safety case to demonstrate that the trial can be undertaken on the existing network safely.
"It's not as if Talgo haven't done this before. They've done similar sorts of trials in India, America and the Middle East."
Freeway taking its toll
Late last year, the Mount Barker Council released a discussion paper on the need for alternative transport routes to the frequently congested South Eastern Freeway.
While Mount Barker is well serviced by Adelaide metro buses, the paper warned of population pressures, with the district expected to increase from about 38,000 to "reach 60,000 in the next 15 years".
It canvassed several solutions — including a road-only series of works "at a cost of more than $2 billion", as well as rail options.
"There appears to be a prima facie case to build a tunnel to run the line from a point around Belair straight down to the Torrens Park/Mitcham area before re-joining the existing Belair line," it stated.
But whether or not that's a pipe dream, most agree that something's got to give.
"We've got a serious problem on the South Eastern Freeway that every time, every morning peak and every afternoon peak, it's getting longer and longer to get into the city. So, we need to look at alternatives," Transport Minister Tom Koutsantonis said.
"Is it more buses? Is it trains? Is it a mixture of things?"
That sentiment is widely shared by residents.
"We've got this great, amazing city developing in Mount Barker. It's growing exponentially," local Chris Reed said.
Gauging support
The Adelaide Hills line rolls through bucolic countryside — but is also characterised by steep sections.
A major impediment to a smooth rail journey is a colonial-era hangover — the difference in gauges.
Unlike Adelaide Metro's rail network, which uses broad-gauge track, the line to Mount Barker is standard gauge.
But tilt system technology used by Talgo means its trains can negotiate corner faster than others and can shift between gauges.
"There are a number of factors in terms of Talgo technology," Mr Rossi said.
"The bogie system is quite different and enables them to travel on the hilly terrain and on the curvatures in particular at greater speed than other rolling stock, but safely.
"They're able to go from broad gauge to standard gauge, standard gauge to broad gauge through technology that they've developed."
Next stop Mount Barker?
It's nowhere as simple as that.
In fact, even getting the trial up and running will be no easy feat.
"Something like a trial of this nature could take eight months to organise — we've got to get the rolling stock out from Spain to Australia," Mr Rossi said.
"What's very important here is analysing the geometry, the curvature, the track, the grades, undertaking the simulation, looking at the level crossings, at all the infrastructure that's there.
"[It's about] ensuring that the Talgo rolling stock will be able to successfully and safely undertake the trial."
But regardless of those challenges, commuters from outside Mount Barker have also expressed a desire for a rail express.
"It would definitely make it a lot faster and more convenient," Liz Polanco said yesterday, as she boarded a local bus.
