Australian examples show difficulties in getting links to pay

Some nearby overseas examples of airport rail links have shown how touch-and-go their viability can be, especially in the early days.

Although only about 3 per cent of trips between Auckland and the airport are taken by bus, a consultants' report in 2008 to the Auckland Regional Transport Authority estimated long-term patronage of a rail service of about 2800 passengers an hour at peak times for the full distance, and 3400 passengers across Manukau Harbour, including commuters from Mangere.

That would be enough to support high-frequency peak service, but not enough to break even without public subsidies.

Brisbane, with a population of about two million compared with Auckland's 1.4 million, supports a privately-run 8.5km viaduct airport rail extension which was almost put into receivership in 2003, two years after it opened.

After a cost-cutting drive, combined with significant passenger growth, the line turned a profit for the first time in 2005.

It had an operating profit of A$4.8 million ($6.3 million) in 2008, making it one of a handful of railway operations in the world to run without public subsidies, and last year carried just under two million passengers.

Sydney, with 4.3 million people, also has a privately-owned airport rail link through a 9km tunnel into the central business district.

Completed in 2000 for A$900 million, it suffered from low early patronage, and was subject of an $700 million Government bailout before building up patronage to almost seven million passenger trips last year.

COSTS OF USING AIRPORT SERVICE

Brisbane
* Cost of airport extension - A$220 million ($287 million).
* Distance to central Brisbane - 15.9km.
* Travel time - 19 minutes.
* Fare - A$15 for adults, free for children.

Sydney
* Cost of extension - A$900 million
* Distance to central Sydney - 9km
* Fare - A$15 ($19.63) from domestic terminal; A$15.80 ($20.68) from international terminal.
* Travel time to Circular Quay - 21 minutes from international terminal.