Farrar & the mystery of induced traffic

Written By: - Date published: 10:16 am, August 7th, 2012 - 8 comments
Categories: sustainability, transport - Tags:

David Farrar notes that 4 of the 10 worst congestion points in New Zealand are in Wellington. He concludes “Transmission Gully will help with some of that, but not all”. Quite the opposite, old boy. Transmission Gully will not create any new capacity at any of these congestion points. In fact, NZTA says it will create more traffic heading into 3 of them.

Here’s the list of Wellington’s top congestion points from the top ten:

4. Johnsonville to Porirua Motorway from Takapu Road to Westchester Drive (Wellington)
6. Western Hutt Road (Wellington)
7. Wellington Urban Motorway (Wellington)
10. Centennial Highway between Johnsonville and Newlands roads (Wellington)

4, 7, and 10 are all citywards of where Transmission Gully joins the existing State Highway 1 motorway. It does not bypass any of them.

NZTA says that Transmission Gully would result in 8% more traffic per day at Tawa – 4,400 more traffic movements a day heading in and out through those 3 congestion points.

This is called induced traffic. If you build big expensive motorways, it doesn’t relieve congestion, it subsidises sprawl and exurb living – meaning more people trying to drive into the city from further away each day.

That’s obviously a bad result for a country that already spends $8.3 billion a year importing oil (our entire current account deficit) but what happens when all that extra traffic tries to get through the existing chokepoints?

Worse congestion, of course.

And then some bright spark says ‘to realise the benefits of the billions we’ve sunk on Transmission Gully, we need to expend billions on adding new lanes to the motorway cityward of Transmission Gully’.

And, so, the cycle continues. Billions wasted on motorway projects that make no sense in their own right and, barely, make sense to get more value out of the previous generation of billion dollar motorway projects. You keep on spending more money trying to alleviate peak traffic but actually increasing it and pushing it around the system. And most of the time, the vast bulk of your motorway network sits idle because you’re building for these daily peaks.

The smart option is long-term integrated city planning designed to create neighbourhoods that don’t create huge amounts of peak traffic every day and transport networks that works sustainably. What we’ve got is piecemeal additions of motorway projects that do nothing to relieve congestion but make it worse.

8 comments on “Farrar & the mystery of induced traffic ”

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  1. McFlock 1
    7 August 2012 at 11:14 am

    lol
    I know reality often has a liberal bias, but it’s not often that geography shows the tories up as lying swine… 

  2. Hayden 2
    7 August 2012 at 12:28 pm

    It (Transmission Gully) might help slightly with out-bound traffic, separating Tawa/Porirua traffic from people going further north, but anyone even vaguely familiar with Wellington should be able to see at a glance that it won’t do anything for peak-hour congestion. Even in peak hour, going north on SH1 it thins considerably past the Ngauranga interchange. It could have a positive effect on holiday traffic going through Plimmerton, but then you’re just sitting in traffic somewhere further north in one of the other bottlenecks.

  3. ghostwhowalksnz 3
    7 August 2012 at 1:57 pm

    More motorways , more traffic, is something Farragoblog doesnt understand.

    We had something similar in Auckland when the new motorway connection from the Airport to the Southern Motorway opened. Right away , there was massive extra congestion on the existing from Manukau City south to Takanini which backed back up to Papatoetoe.

  4. Shaz 4
    7 August 2012 at 11:42 pm

    Good post. These complex problems require systems thinking and they are getting linear thinking, if that. Promoting more and bigger roads are another instance where “common sense” is actually nonsense.

  5. Tracey 5
    8 August 2012 at 10:22 am

    Anyone notice that all motorway extensions eventually open at full capacity… it’s a money-go-round for sure. Which companies are the major beneficiaries of this form of state subsidy??

  6. tc 6
    8 August 2012 at 11:55 pm

    DPF just doing his job of selling RONS by ignoring logic, evidence and lying his mostly taxpayer funded arse off for his masters.