Free transport for superannuitants is driving up demand for public transport in Auckland, say bus companies.

SuperGold Card holders became eligible on October 1 for free travel from 9am weekdays and all weekend.

The $72 million Government initiative aims to make half a million elderly people throughout the country more mobile.

NZ Bus northern region general manager Warren Fowler said more Aucklanders were hopping on public transport, especially the elderly.

"Senior citizens are enthusiastically taking to buses and enjoying the opportunity of free off-peak travel.

"We have seen the number of senior citizens double on some routes."

Auckland retiree Viviane Drury has been making most of her free transport.

"I use the link everywhere. I am going out to town ... and my friends are all going out to Waiheke Island."

She said she loved the fact she didn't have to pay because it allowed her to go out and about more often.

The elderly are not the only reason for the rising popularity of public transport.

High petrol prices continue to boost passenger numbers on buses, Mr Fowler said.

"As petrol prices continue to remain high, people will continue to look for smarter ways to spend their disposable income. Catching the bus is clearly one of those."

An Auckland Regional Transport Authority (Arta) spokesman agreed that high petrol prices encouraged more people to use public transport.

"[Petrol prices] have gone down but they are predicted to rise again - so again that is a push factor for getting people on to public transport, and once people try it we find they like it."

A recent Infratil report revealed Aucklanders had made almost 20 million NZ Bus trips, 7 per cent more than in the previous six months.

Arta reported rail as the fastest area of growth in public transport within Auckland.

It responded to the surge in rail use by adding more carriages and services to the southern and eastern lines recently.

Mr Fowler said ongoing improvements to infrastructure and services also contributed to growth.

After the completion of the northern expressway there was an 86 per cent increase on some express services.

The Mt Eden bus service had also been a big growth area, increasing by 16 per cent after more buses were provided, he said.

However, not everyone is happy.

Grey Power national president Les Howard said the SuperGold Card scheme didn't go far enough because small-town retirees were missing out on the benefits of free public transport.

"It works well in a town or city which has a public transport system," he said.

"Anybody who doesn't have a regional council bus service, it doesn't do a lot for."

Superannuitants living on the West Coast of the South Island are one group who do not qualify for free transport.

Mr Howard said he wanted free travel to be extended to inter-city buses and the interisland ferries.

By Marika Hill