19 November 2005

Wellington: Paremata congestion gone

Stuff reports that it seems that the much maligned Mana highway upgrade has done the job – morning and evening peak congestion has been eliminated. After much criticism that the $24 million upgrade was a waste of money and it should have been spent on the cargo cult called Transmission Gully – the $24 million upgrade works! A bit cheaper than the $1.1 billion price for Transmission Gully, but then the advocates of Transmission Gully have almost a social credit view of economics. The Mana upgrade had a benefit cost ratio of over 5:1, Transmission Gully is around 0.5:1 - it is obvious which project is a good investment.

The upgrade was based on a simple premise – the problem is that two lanes of free flowing traffic merge into one for several kms. So the solution was fairly straightforward – ensure two lanes flow between those points. The bridge was duplicated to create two lanes each way, and the road widened from Mana Esplanade to the 4-lane highway north of Plimmerton. In between those points parking is banned at peak times so an extra lane can operate in one direction. Five sets of traffic lights ease the flow from side roads, improve local and have not hindered the flow. In fact, the cops are concerned about speeding along the road now!

Who needs a 27 km hilly 4-lane motorway to fix this problem? Only stupid central and local body politicians addicted to spending other people's money promote this, along with a small number of local residents who will benefit from their properties not being on such a busy highway.

Now this wont be a long term solution, Transit says ten years and traffic growth will have filled up the road capacity. In the meantime, some consideration can be made about how to plan to fix that - a bypass at Mana is the best answer at around $220 million.

Ten years saving $1.1 billion on Transmission Gully (or $220 million on a Mana Bypass) is worth a good bit of money – at 5% interest a year, minus inflation it is still over $200 million in net savings from NOT building Transmission Gully. It is time to stop building roads well in advance of them being needed – if Transmission Gully or a Mana Bypass are to be built they it shouldn't be before 2015-2020 – and by then there may be congestion pricing, which could mean nothing need be done. The money can be used for something else.

So the pressure should be off – Paremata is no longer a traffic bottleneck, for now – another reason why politicians shouldn’t decide road building based on media driven popularity contests – I doubt if any Members of Parliament given a list of roading projects could decide what are the best ones.


Anonymous said...

Have you any thoughts about Graham Hancock's report re the relative seismic merits of the Coastal Highway versus TG?

Libertyscott said...

Honestly, haven't seen it.