But what is shaping up as the most promising little earner is what they call "landside access revenue" – the money the airport charges taxis, buses, Ubers and car services to drop off and pick up travellers. The 2018 take was not a huge part of the airport's income at about $23 million, but it's growing fast – up by 19 per cent that year and 14 per cent the year before. So if you've got the lucrative lock on automobiles and planes, then why not trains? Illustration: Matt Davidson Credit: The airport is part of a syndicate that wants to throw in $5 billion to the state and federal government's $15 billion airport rail line, the project we've been awaiting for as long as there's been an airport at Tullamarine. The joint venture also includes the operators of Southern Cross Station and Melbourne train contractor Metro, with financial grunt supplied by industry super fund investment house IFM. The consortium has a slick website that says all the things we want to hear about airport rail. Travellers are promised a smooth 20-minute journey to the airport from Southern Cross via a brand new, you-beaut double rail tunnel – which could also be used to run a lot of much-needed fast trains out to places like Geelong and Ballarat.

Reasonable ticket prices are being offered too, less than 20 bucks in today's money for a one-way ride. With 16,000 cars each day to be taken off the Tullamarine Freeway, it sounds like a pretty good deal all around. But the question is, when did Melbourne Airport ever offer anybody a good deal? It's clear what the airport wants: to keep its stranglehold on that "landside access revenue" – because being a monopoly player is its winning strategy, first and last and always. An artist's impression of the airport rail link station. Credit:Melbourne Airport What's in all of this for taxpayers is less obvious. So the fine print of this proposal should be a must-see for the savvy traveller. Here are a few questions to get the ball rolling. Who's going to dig this tunnel? The state government or the rail consortium? And who would then own it? What about the tracks, the trains? Would the state government have to try to expand, run and maintain its rail network to the west of the state using a privately owned tunnel? How much would it be charged for such a service? What guarantees are being offered on reasonable fares into the future? What return on investment do the joint venture partners want?

There are lots more questions, but don't expect answers soon. Nearly all of the "market-led proposal" is being kept under wraps, with only the ritzy public relations guff available for public scrutiny while the state government's Treasury Department sizes it up. The secrecy is established protocol in these things, the government insists. So we wait. Loading Now, this all plays out against the background of a campaign led by major and regional airlines for a better deal from Australia's airports, with the carriers saying they and every other airport user have been getting rinsed for years by what are effectively unregulated monopolies. The man who ticked off on the privatisation of Australia's airports while transport minister in the Howard Government, John Sharp, is now the chairman of Rex Airlines – part of the better deal campaign. And dear me, has Sharp's past come back to haunt him. "It was never envisaged ... that the airports would simply be left – unconstrained by either competition or regulation – to behave and charge as they like," he wrote recently. It was envisaged, actually John. It's just that you and your colleagues didn't want to know about it. But Sharp's warning, that privatised airports have been a dud for Australian consumers, shouldn't be ignored. None of this proves that private rail run by an airport will be a stinker of a deal for taxpayers and travellers, but it would be nice if we could all have a look at what's being proposed here and make up our own minds.