The Capital choking on traffic congestion due to the RoNSzi scheme

2 09 2013

Today there was a bit of a hoo haa in the local press about the Arup and Opus report that the Greater Wellington Council commissioned on the effects of the RoNS on the Wellington region, but then embarrassingly the GWRC has been trying to ignore ever since.

It seems that the Airport to Levin corridor part of the Roads of National Significance is going to have quite an effect. Because of Transmission Gully and the Sandhills Motorway projects the congestion in Kapiti and Porirua (ie Mana and Pukerua Bay) is going to fall and with the Petone to Grenada project Hutt Road congestion is also going to fall a bit, but with induced demand and extra trips the now efficient roads are going to funnel many, many more cars onto Wellington and Wellington just isn’t going to cope.

Because reducing congestion is one of the reasons that the RoNS are getting foisted onto the public it is a bit embarrassing for the government and for the pro-roads part of the GWRC, since the RoNS are going to fail to solve the problem they are designed to solve, namely congestion. Because that’s generally a stuff up and because of their staggering expense, the government should really go back to first principles and start again on its transport policies.

There seems to be some confusion whether the report has been made public yet (although it’s been funded by GWRC rateapayers so they bloody well deserve to be able to see it) and there are accusations of leaks and although it isn’t too hard to find on the interwebs I still feel a little reluctant to post the whole thing, so I’ll just post some highlights. I really hope that it is officially released through appropriate channels very soon now.

Firstly the report assumes the RoNS projects and the Petone-Grenada link get built. It doesn’t entertain other options. It also assumes that there are no public or active transport improvements and it is just business as usual on those fronts with no great modal shift to bikes or trains and trams, and it assumes that parking capacity in the CBD will grow to meet demand (like where?). It also doesn’t assume any oil shocks or similar. It does however assume continued growth of car trips, ignoring any evidence of peak-car (just like the business case for the RoNS does).

You can see that graphically. I think some of its assumptions are wrong. I think the green and red will both grow especially if we build separated cycleways and we build light rail to Newtown and Kilbirnie.

TripsByMode-AM peakThen here is a graph of vehicle to capacity ratios at key bottlenecks in the AM peak with those assumptions. The higher the V/C the worse the congestion. There are some improvements by 2031 in some places and some things are getting worse. State Highway 2 seems to fare the worst.

VCatBottlenecksThis is the most interesting graph in the report.  Below LOS D means below a level of service where the volume to capacity is greater than 0.80, i.e. congested. And it can be seen that in Wellington many more vehicle kilometres are going to be spent waiting in traffic.  In fact it means that congestion in Wellington is going to be up 80% with greatly increased fuel imports to match.

CongestionGraphically that means that instead of these current conditions of 2011:2011LOSPlotThat it is going to look like this by 2041. (There is a lot more orange and red)

2041LOSPlotTo put it mildly, that’s a bit of a debacle that we are going to pay billions of dollars to do to ourselves. In fact so much traffic would completely destroy the city. There has to be a better way than overbuilding motorway capacity that induces demand that then dumps thousands of extra cars onto a small city whose built form is dictated by the steep topography and the collection of tram based suburbs that it largely still is.

The RoNSzi scheme is unsustainable financially or environmentally. In a time when cities need to be talking about sustainability and alternative transport here we have a 1950s solution that is no solution at all.




2 responses

4 09 2013

Hi – good analysis.

The report is not confidential: I asked GWRC for a copy, and they sent it to me.

4 09 2013

Thanks Mike, that’s good to know.
Anyone want a copy just ask.

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