Key Points:

Every morning for the past few years I have driven into the city on Auckland's northern motorway with mounting amazement. Alongside me a monstrous environmental destruction has been proceeding without a whisper of objection.

It started somewhere north and since coming into my view has bowled several stands of fully grown trees, scraped chunks out of parks and school grounds, sliced the side of a native bush reserve and, arriving at the Waitemata, marched onto the mudflats.

That's where my astonishment really started.

I came to Auckland 35 years ago, about the time the citizenry had broadly agreed the expansive beauty of their harbour could bear no more reclamation. I was just in time to cover the victory of environmentalists in Ngataringa Bay.

Ever since I have blessed the fact that the bridge, the motorways and especially the sublime Tamaki Drive were built before anyone had heard of ecology. As Aucklanders say, you'd never get permission to build them today. Or so we've thought.

There, alongside the Northern Motorway, bulldozers and pile-drivers and earth-moving buckets were day after day covering mudflats and mangroves with the base coarse of a two-lane highway for public transport.

Blessed public transport; thanks to global warming it has made concrete on the coast conceivable again. Henceforth when objectors to coastal development invoke the essential place of mangroves in the marine habitat they will have to concede that it all depends.

Build a bus road and molluscs can die.

The self-contained "busway" is practically complete now, with stations, car parks and access roads built and no expense spared to provide an enclosed overhead walkway to a tertiary campus for students who might use it.

It is a striking sign of the economy's new wealth that politicians dare make such an investment. Nobody would put their own money on the prospect that commuters will leave their cars at home, or at suburban terminals for the day, in sufficient numbers to make it pay.

Reportedly the parking lots are already filled most weekday mornings but it has made little difference to the motorway congestion. The public transport entrepreneurs intend that we forsake the car entirely and take a bus to the busway. I hope they are right but I really don't think so.

Still, it is a road and there is an economic use for it. It is self-contained, access is easily controlled. Eventually it could be a tollway for general traffic, the only reliable solution to congestion.

For the moment, its arrival on the landscape is a reminder of a wider political debate we need to have at the next election. For nine years the present Government will have been spending the dividends of economic reform.

The Prime Minister complains now that if the Treasury had not consistently underestimated the economy's strength the Government could have also cut everyone's taxes, years ago. Next year, she says, it will.

The National Party no doubt will trump any tax cut it gives. The surplus will not survive, and I wonder if this is wise. John Key believes the economy is ready for a big burst of public investment, not necessarily in busways but certainly in infrastructure to expand the country's economic capacity.

If Key is not left with a Budget surplus he is prepared to invest with debt. Personally, I would sooner it was a surplus.

Voters could let parties know we are not interested in a tax-cutting competition next year, we want to compare their investment ideas. There could be quite a contrast. Labour would put environmental "sustainability" uppermost, pointing proudly to the busway.

National would argue for a revision of the Resource Management Act to enable investments to proceed, like the busway, without frustrations in the mangroves.

Labour speaks the language of economic development sometimes but its actions attest to other priorities. Never more dramatically than in the punishment of Trevor Mallard for punching an antagonist.

Mallard's driving efforts for the America's Cup and the Rugby World Cup 2011 have been invaluable, if too daring in advocating an Auckland waterfront stadium. He combined the work of economic development and sports minister with enthusiasm and imagination. To drop him from those roles speaks volumes about Clark's priorities.

She and the country she leads have temporarily lost a sense of proportion on certain subjects. A change of government can change much.

It would certainly change the relationship of the public and private sectors. Private schools and tertiary training, private health and accident insurance, private security and prison services, private transport and roading projects would probably all be able to help the country's development in ways that are not made welcome now.

The busway, for example, could be a fast lane not just for old-fashioned services between terminals but for taxis, door-to-door shuttles and private cars, all running on biofuel and carbon-credited of course.