The lure of a $42 billion stimulus package has shaken the dual transport totems of fast trains and a second Sydney airport (anywhere-but-in-Sydney) out of the closet once more.

Stephen Byron, the managing director of Canberra Airport, made a call for the building of such a rail link between Sydney and its airport to Canberra and his airport this morning shortly before attending a regular meeting of the Airports Consultative Forum at the Department of Infrastructure.

His formula, fund the 50 minute high speed line ($8 billion) out of the money saved on building a new airport somewhere else, like Goulburn, or Newcastle, or maybe on top of the Bradman Museum in Bowral.

Why is the idea of a rural Sydney airport barking mad? At the outset no-one who has a specific reason to fly to or from Sydney is going to use an airport that is not in Sydney.

The time and cost burdens don’t work. The decision to restrict Sydney to one airport means that it will decline in relative economic importance compared to cities that have efficient air services because the generators of high levels of business travel will go elsewhere.

The policy of an airport for Sydney in whoop-whoop is unenforceable. Nobody has to base companies in a city that is hard to reach by air, or for that matter, hard to move around by any means of transport, or one that having expelled shipping from the harbour, is left with no real answer to port congestion other than run cargo through Port Kembla or Newcastle.

Sydney is dying from infrastructure choke. The bill for saving it is simply insupportable, politically and monetarily. Melbourne and SE Queensland, especially between South Bank and Surfers, will easily eclipse the Sydney basin in coming decades, aided by a century of unrepentingly poor infrastructure planning.

Byron, who is most definitely not barking mad, is wrong about a 50 minute high speed rail trip from Canberra to Sydney. The maximum velocity of the fastest metal wheel on rail trains in service is 320 kilometres an hour. The straightest possible route from his airport to Sydney’s is 236 kilometres, and that involves amazing tunnels or bridges under or over dam catchments and gorges, plus through a large swathe of hot, methane rich coal seams.

Realistically, without near total track realignments, a Sydney-Canberra train could get to the airport or Central in about 90 minutes, half the drive time if the roads are clear, but from which getting to any other part of Sydney is a shambles that makes driving yourself far better than even flying between both cities.

Canberra Airport does have a bright future without entertaining the fiction of becoming a second Sydney Airport for regular travellers. Operators like AirAsiaX have business models to cater for a new category of low fare, long haul leisure travellers who want to visit eastern Australia, and don’t care where they land.

That model is already working well for AirAsiaX on the Gold Coast, and has been scoped by Emirates for high capacity 650 seat plus services by A380s to Adelaide. Jetstar has been keeping a close eye on how long haul low cost flights using secondary airports could work, and Ryanair and Air Berlin have similar ambitions for the trans Atlantic market.

But those studies aren’t predicated on huge infrastructure spends, only on their predicted attraction for low cost high volume leisure passengers. If this mass leisure model clicks it could totally transform Canberra’s airport by 2020. And if they come those passengers will be met by buses, or at best a slow train to Sydney, not some loss making super train ignored by most of the locals and gifted to them by an Australian government.