The engineering think tank Beyond Zero Emissions recently released a report on the construction of a high-speed railway. The project’s leader, Gerard Drew, told a meeting in Sydney that on his scheme the Brisbane, Sydney, Canberra, Melbourne corridor would be linked by 2030 with trains running at 350km/h and possibly faster.

The study proved such a project could be justified. More importantly, perhaps, it demonstrated it could be financially viable. “High speed rail would halve air travel,” says the group’s chief executive officer, Stephen Bygrave. “It’s faster, more convenient and it will make a profit.”

On the basis of overseas experience, the study team estimated that, if the line was built by 2030, 65 per cent of people travelling Brisbane–Sydney or Sydney–Melbourne would use the train. Given current projections of the growth of traffic along the corridor, that implies about 68 million passengers a year.

Were such a project ever to come to fruition, there is no doubt it would scare the living daylights out of aircraft operators such as Qantas, Virgin and Tiger. It’s doubtful if they gave it a second glance, however.

Indeed, why would anyone give a report on Australian high-speed rail a second glance? The subject has been studied over, and over, and over again.

The first report into something approaching high-speed rail seems to have been a 1981 proposal from the Institution of Engineers. It envisaged the electrification and improvement of existing tracks around the coast, from Adelaide to Brisbane. It would not have led to very fast trains – train sets with a sustained speed above 200km/h – but it would have greatly reduced journey times.

The first report to recommend a genuine very fast train was a 1984 study by the CSIRO’s Paul Wild. Since then, there have been six more reports. They all say much the same thing: a VFT system would be worthwhile; it will cost a lot and take time to build. The government’s response has never varied: it will cost too much.

Other governments have reached different conclusions. Since that 1981 proposal, close to 40,000 kilometres of fast train track has been laid, but none of it in Australia. In 1981 there was about 1500 kilometres of fast train track around the world and China had as much as Australia. By December 2013, however, China had 12,000 kilometres of track that could sustain speeds above 200km/h. By 2020, that figure will exceed 16,000 kilometres. Today, Europe is crisscrossed with high-speed routes. Globally, 3200 train sets are in operation.

The problem, of course, is cost. To travel safely at speed, the alignment must be smooth and straight. In the Drew plan, 180 kilometres of the 1799-kilometre route is either elevated or underground. Tunnels account for 15 per cent of the cost of preparing the alignment and bridges add another 13 per cent. The total cost of the track and its associated earthworks is $61.4 billion.

For the purposes of the study, Beyond Zero Emissions added the cost of rolling stock, 10 per cent for management costs and 15 per cent for contingency. The total cost came to $84.3 billion.

But there is promise in the Drew report. Even making conservative assumptions, it says the likely revenue would be $6.9 billion, which yields an operating profit of $4.6 billion. Using normal accountancy rules, this would return more than 4 per cent on the original investment.

So, if the infrastructure is necessary, and we can pay for it, why is there such reluctance to go ahead? The High Speed Rail Advisory Group, which was established by then transport minister Anthony Albanese, noted in its report that “the greatest immediate threat to high-speed rail in Australia … is simply inertia, brought about by perceptions that, even if desirable in concept, high-speed rail is unrealistic or not within the contemplation of current generations”.

The most obvious cost of inaction is cost. Year after year, it climbs. Wild’s 1984 study hazarded a guess of $2.5 billion. Transport minister Peter Morris put a red line through it that same year.

John Howard did the same thing to a similar report in 2000 that required $1 billion from the government. Fifteen years later, Albanese’s phase 2 report put the cost at about $120 billion. Even he conceded that assembling that much would be “challenging”.

Part of the price increase can be put down to inflation; part to land development along the rail corridor. The majority of the tunnelling along the route is not because of the hills, it’s because of the houses.

The best that can be said for inaction is that it has made some of the advantages of a very fast train more obvious. In the 1980s, it was possibly a valid argument that the density of population that underwrote early very fast trains in Europe and Japan did not apply in Australia.

It does now. According to a report by Amadeus Air Traffic Travel Intelligence, Sydney to Melbourne is the fifth most heavily trafficked air route in the world. The others, in order, are Jeju–Seoul; Sapporo–Tokyo; Rio de Janeiro–São Paulo; and Beijing–Shanghai.

But does this make the case obvious enough? The politics are confused.

On the surface, the prospect is poor. With Treasurer Joe Hockey so obsessed with balancing his budget, and the prime minister convinced that “even the humblest person is king in his own car”, this is a government with little appetite for major spending on rail. Indeed, one of the first moves of the Abbott conservatives on taking office was to shut down the High Speed Rail Advisory Group.

But the politics of the very fast train are complicated. It received bipartisan support throughout the highly fractious Rudd and Gillard parliaments. Tim Fischer, long-time leader of the Nationals, was a member of the High Speed Rail Advisory Group. The Nationals’ current leader and deputy prime minister, Warren Truss, is one of the most enthusiastic advocates of high-speed rail in the current parliament.

The Greens are highly supportive. In fact, their agreement to support the Gillard minority government included a commitment to conduct a study into high-speed rail.

There is also a large and increasingly vocal lobby in local governments. Geoff Kettle, the mayor of Goulburn and a former Liberal Party staffer, says he is organising a lobby group composed of mayors from every local government area along the proposed route. Labor, of course, has a strong record in the area. The current interest in the subject stems from the 2010 report to Albanese, then the transport minister in the Gillard government.

Having said that, every one of these supporters would expect to find opposition within their own ranks. There will be plenty of Greens who oppose a VFT on the grounds of noise and the alienation of national parks and other environmentally significant sites. Economic dries in any of the other parties will oppose it on the ground that it would be difficult to fund without significant levels of government debt.

In the manner of these things, it’s not clear whether the debate has already been lost, or whether it has yet to begin.

Tony Abbott has on many occasions, declared himself to be the “infrastructure prime minister”. He has raised public spending on infrastructure. He has committed $11.5 billion to new transport routes, but it is all gone on roads. Only $180 million over four years has been committed to rail, that for an inland freight route between Melbourne and Brisbane.

The prime minister has rarely, if ever, attempted to justify this in public. Since almost all transport experts agree the key to fixing congestion in our cities is better public transport, this is not surprising.

A debate of sorts is beginning. In December, Albanese introduced a private member’s bill to the House of Representatives. It would establish a high speed rail planning authority to engage in land use planning along the rail corridor. It is currently stalled before the House of Representatives Standing Committee on Infrastructure and Communications.

It will probably stay there. If the very fast train is to proceed, the prime minister will want to put his stamp on it. If he doesn’t, the very fast train will remain, as it is today, an overseas experience.