Key Points:

The question that transport planners need to keep in mind when considering whether to create a cycleway across the harbour bridge is not "Who thinks it's a great idea now?", but rather "Who is going to realise what a great idea it was once it is built?".

The Auckland Regional Transport Authority board this week decided to support a consideration of a cycle and pedestrian path on the bridge as part of a three-year transport programme. The Government's Transport Agency, however, which will be footing the bill of as much as $43 million, says it won't decide until the end of this year whether to recommend it.

A vociferous cycle lobby has good claim to the moral high ground in the debate. Climate change, traffic-choked roads and the remorselessly increasing price of fuels drawn from the earth's dwindling and finite reserves all argue for the value of getting more commuters out of their cars.

The more of them who get on bikes, the better for the nation's cardiovascular health. And the more those cyclists are separated from motor traffic the less their mishaps will cost the public purse.

Critics of the proposal point to the indifference cyclists have displayed towards trial schemes to provide shuttle services across the bridge, and the small numbers using existing ferry crossings. But such an argument is specious: the possible popularity of a bridge cycleway may not be inferred from the popularity of a shuttle service. For the physical effort that they expend - plus the perils posed by bad weather and worse drivers that they endure - cyclists feel they have bought a degree of freedom.

Scheduled services are at odds with their kind of commuting and they can scarcely be blamed if they decide to leave their bikes at home.

Those who designed the Auckland Harbour Bridge made a mistake in not including provision for cyclists and pedestrians. But it would be a shame if we repeated this shortsightedness by ruling out the cycle option. Even at the upper end of the costings, $43 million is a modest expenditure when compared to the $3 billion starting point for the second harbour crossing which is is, in any case, years away.

It is inconceivable that cycling - of the recreational or commuter variety - will ever become as widespread in the City of Sails as it is in Amsterdam or Copenhagen or in many cities in Asia where many people cannot afford motorised transport. Auckland is too spread out and too hilly to make cycling widely attractive. Moreover, as we now realise to our cost, the transport planners of the 20th century missed the opportunity to build a mass public transport infrastructure or even to set aside corridors that would have made it an easy option to implement later. But posterity will not thank us for turning down a relatively cheap proposal to increase the transport alternatives available to Aucklanders. It should have been a priority long ago, and it certainly should now.

The numbers using a bridge cycleway may be small to start with but anything that encourages people to get off the road is simply good urban transport planning. What is more, it will be its own advertisement in years to come: to a gridlocked commuter, the sight of 18-speeds whizzing by is food for thought.

All that said, the region's cycling fraternity may like to consider their public image. The expenditure they seek is high in terms of dollars per person-kilometre travelled. Motorists can and should silently thank every cyclist they see for removing another tonne of metal and plastic from the traffic stream. But the patience of motorists is stretched by the antics of some cyclists who act as though the road rules don't apply to them. They do, actually, and will do so until, some time in the distant future, the whole region is a cycleway. In the meantime, a little courtesy would not go amiss.