The Melbourne and Sydney housing affordability story has become a transport story, because as prices have risen so have commute times - and that severely limits options for those trying to buy on a budget.

The train journey from Newcastle and Penrith to Sydney's CBD is slower now than it was 30 years ago, according to PwC transport expert Robert Williams, and it's a similar story with Melbourne's nearest towns and cities.

Connecting Melbourne, Sydney and Brisbane via high-speed rail is hysterically expensive, but connecting places like Geelong and Ballarat to Melbourne, Newcastle and Wollongong to Sydney, and Toowoomba to Brisbane with trips of around 45 minutes is more doable.

And it's bait.

Bringing down those commute times from the ballpark of one to 1?? hours each way to about 45 minutes would offer an attractive opportunity to the huge number of Australians currently locked out of major city property markets. They could move to regional hubs and keep their city jobs without sacrificing three hours or more to the daily commute.

That's how you ease capital city house prices without having to tamper with negative gearing or capital gains tax exemptions. It'd also help decongest city roads and boost regional development.

Trying to link the cities is where the idea falls apart

The current federal high-speed rail plan is expected to cost $114 billion and take another 50 years. Let those numbers sink in and remember that running over budget and time on infrastructure projects is a proud Australian tradition.

For that much money you could build five UK-France Channel tunnels, Four Hong Kong International Airports, about 60 per cent of the International Space Station, or even, if you're feeling a bit loose with your inflation adjustments, one Great Wall of China.

That price tag and time frame was cooked up in 2013 during the Department of Infrastructure's HSR (High-Speed Rail) Phase Two Report, which of course followed a phase one report in 2011, and before that a strategic study, and several advisory boards and committees dating to the mid-1980s.

But instead of putting the whole idea away, the 2017-18 budget included another $20 million in funding to support the development of business cases. A prospectus is on the way and proposals are due in September - three will receive Commonwealth funding.

An alternative to air travel is a want, not a need

Unfortunately for fed-up air travellers, a rail alternative to air travel would be an expensive luxury given the level of competition and efficiency shown by the aviation industry.

Thousands of kilometres of rail would need to be laid and tunnels would need to be bored - including underneath the country's three biggest cities. It'll cost significantly more than the entire market value of Westpac Bank before maintenance costs even begin.

Now consider that the entire first phase of Sydney's second airport at Badgerys Creek is expected to cost $1.4 billion.

Give Sydney and Melbourne airports a little credit. In the year to May the Sydney-Melbourne route saw a record 8.94 million passengers, according to the Bureau of Infrastructure, Transport and Regional Economics. It's the fourth busiest path in the world, but while passengers often grumble about delays and customer service, the system is far from broken.

Improvement in efficiencies in managing greater numbers of air travellers is being noticed, according to CommSec chief economist Craig James.

"The latest data on domestic aviation activity is further evidence that the economy is doing well," Mr James said.

"The record number of business people travelling between Sydney and Melbourne further highlights the good conditions being experienced by corporate Australia."

Melbourne Airport chief executive Lyell Strambi said Melbourne was on track to welcome 60 million passengers annually, as soon as 2033, and predicts its new runway development will be operating between 2022-24.

"A new runway, along with improvements to the capabilities of existing runways and taxiways, is vital infrastructure that will facilitate continued growth in airline services, particularly from international carriers upgrading their fleets with efficient new-generation aircraft," Mr Strambi said.

A high-speed rail alternative would be great, but it's not a pressing need.

For the government, a non-committal 'we're looking into it' is the safest bet

"Spending [$114 billion] on east coast high-speed rail, which largely benefits wealthy business travellers, frankly, who are currently catching airplanes between those two capital cities??? it's not great politics if you live in western Sydney or Adelaide or Perth, or everywhere else," Robert Williams, who is responsible for PwC's Strategy& Defence and Transport practices, told Domain.

"Is that a good use of the nation's resources given it's going to need a lot of taxpayer funding?"

Governments don't like to say no, but given the current HSR estimates assume constructions costs will fall as technologies improve, any current business proposals will have to be decades ahead of the pack if they're going to be at all useful.

But Australians should prepare themselves for a never-ending supply of high-speed rail studies, committees, advisory boards and feasibility studies - at their expense. Because Australia has a history of doing things this way.

"On Federation the government committed to building a rail link to Darwin, they just didn't say when they'd build it. There were 27 or 28 studies over the years until they eventually built it in 2003," Mr Williams said.

"I guess [this high-speed rail project] is a bit like that. The conditions right now are such that it's not viable..."

Rather than wasting more time and money promising to send trains hurtling up and down the entire east coast, the Department of Infrastructure should strip back its high-speed rail plans and focus only on the area it'd have the biggest impact - everyday commuting.