Don't Transmission a Whole Gully

Tuesday, 30 June, 2009

Don Carson

Don CarsonHalf a Gully is actually better than a whole one. Building the northern section by itself makes much more sense than the whole highway.

The US marines nearly built a road through Transmission Gully to get out of Wellington during World War II. Their generals didn't trust the coastal highway to their marine base at McKay's crossing, just south of Paraparaumu. They never built it. That's a shame, it would have saved the agony of decision making – or lack of it – that lasts to this day.

The given options for fixing the bottleneck to the north of Wellington are all or nothing. On one hand, widen the existing coastal route. On the other, Transmission Gully, which is even more billion dollar plus.

The coastal road tart-up ought to be a dead duck. It's been polled out by the public so overwhelmingly that even a Latin American dictator would blush at how resounding the vote was. The disruption would last for years, the legal obstacles potentially fatal in themselves and the outcome not much better than the existing highway.

But it's cheaper than Transmission Gully, and thus attractive again.

There is another option. If you start with the fundamentals of the problem; frequent gridlock north of Wellington to the west. And then the basic solution; four lanes of highway all the way between Paraparaumu and Wellington Airport. Trouble is, the planners have never seen it this way. They wanted a bypass for the coastal congestion – that's all.

You don't need the whole Gully. Look at the route as proposed. It heads inland from just north of Paekakariki, goes round the back of Pauatahanui, and then flees back to the existing highway again at Linden. It's a billion dollar bypass. For less than that you could get a better and bigger picture solution.

The northern Gully route should go ahead – and then flow into the existing State Highway 27 at Puatahanui. This would mean upgrading SH 27 to four lanes, and it would mean an increase of the Petone to Ngauranga highway to six lanes to take the extra traffic. This last bit ought to be done anyway, since that vital strip of road is so vulnerable to closure with slips and accidents.

The advantages over the planned Gully route are;

  1. It's far cheaper, about half the cost.
  2. Though probably slightly longer, it makes as good a link between Paraparaumu and Wellington as the full Gully project.
  3. It improves the Hutt Valley and Wairarapa link to Wellington.
  4. It reduces the chances of earthquake or flood cutting Wellington off, since it separates the coastal highway from this new route to a much greater extent and thus spreads the risk.

Local politicians ought to go for it. Roading money saved could go to pet local projects. These are the Cross Valley Link for Hutt City and Wellington City wants the CBD to the airport. Money is already going into improving the hairpin bends over the Rimutukas.

The whole Transmission Gully project is already compromised by reducing its connections at the back of Porirua in the latest plan. The cost will take just about all the region's roading money for a generation (and yes I know that the NZ Transit Authority money pots and local body ones are purportedly separate). And there is the looming consequence of post peak oil prices driving cars off the road and so clearing all but the Christmas Day gridlocks.

If Minister Stephen Joyce is going to flip the coin on the two way decision in the next few months, he should consider that there is a third way as well.

What do you think? Leave your comments here.