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Shifting the problem, not solving it

It’s generally accepted that the Victoria Park Tunnel represents probably the most cost-effective project out of the entire Roads of National Significance package. This was confirmed by the SAHA report, which puts the VPT miles ahead of any other project in terms of its cost-benefit ratio: 
For southbound traffic, the project has worked wonders – at least making it easier for traffic to access State Highway 16 westbound (which will be important post Waterview Connection as the primary route from the North Shore to the Airport), the Port and the Cook Street offramp. Interestingly though, there has been relatively little increase in daily traffic over the Harbour Bridge, with NZTA’s latest monthly traffic update showing just a 1% increase in Harbour Bridge traffic in July 2012 compared to July 2011.

For northbound traffic, the story is a bit different I think. While traffic patterns won’t really settle down until after the Wellington Street onramp is reopened, already there has been quite a few noticeable changes to traffic patterns in the past few months – especially in the evening peak. To analyse this further, let’s step back a while to before the VPT opened. At this time the big bottleneck was where the SH16-SH1 ramp and the Wellington Street onramp (when it was open) joined in with northbound SH1 traffic into just two lanes over the Victoria Park Viaduct. The two northbound lanes couldn’t cope with the volumes, which tailed back through spaghetti junction often back to Gillies Ave.

However, what the Victoria Park Viaduct bottleneck actually did was limit the number of northbound vehicles that could hit the Harbour Bridge at any one time to the capacity of the two lanes on the viaduct plus Fanshawe Street plus Curran Street. With a bit of ramp signalling at Curran this seemed to work quite well and even at the peak of the afternoon peak, northbound traffic flowed fairly smoothly over the bridge at least as far as the Esmonde Road interchange. In other words, the bottleneck at Victoria Park didn’t allow too many cars over the bridge during any particular hour – which meant that the motorway north of the Harbour Bridge (at least as far as Esmonde Road, I rarely travelled further north than that so can’t comment too much) didn’t get too jammed up.

Once the third northbound lane of the Vic Park Tunnel was opened earlier this year, everything changed. Many more cars were able to get through each hour, which meant that the Harbour Bridge now had to cope with three lanes of traffic through the tunnel plus Fanshawe plus Curran. Wellington Street’s closure probably didn’t impact on this much as most of its traffic probably diverted to Fanshawe and Curran – meaning it was joining the motorway anyway before the traffic hit the bridge.

My observation is that the Harbour Bridge has coped with this increase reasonably well. I remember reading through the documentation that accompanied the Victoria Park Tunnel proposal and a lot was said about the project resulting in the capacity of the bridge being fully unlocked and utilised. The bridge is slow, but it moves – and that’s pretty good for a piece of infrastructure that really should be squeezed as hard as it can be – given the eye-watering costs of another crossing. The issue is mainly with further north, as on most days it seems there are now stopped cars tailing back a lot further – not just north of Esmonde Road now, but in fact frequently right back to the old toll plaza near the Stafford Road offramp.

My point here is not necessarily to suggest that the Victoria Park Tunnel was a waste of time, but rather to highlight that by removing a bottleneck in the motorway system it has allowed many more vehicles through that pinch-point than before, and as a result it has put a lot of pressure on another part of the network. This means that all users of the motorway have not necessarily benefited from the Vic Park Tunnel project:

  • Those travelling from the city centre to parts of the North Shore beyond Onewa Road in the evening peak may well have seen their trip times lengthen due to greater congestion on the northbound side of the Northern Motorway
  • Same for those travelling from Curran Street, who have also seen the ramp signal “wound back” to let through fewer vehicles to stop the harbour bridge from getting jammed up
  • Those travelling from Onewa/Esmonde to parts of the North Shore further to the north in the PM peak may well have also seen their trip times lengthen

I do wonder whether, in the cost-benefit analysis of projects like the Victoria Park Tunnel, all these negative travel time impacts are taken into consideration as well as the positives. I do think that on balance the project has probably made a positive difference, but remember it did cost around $400 million and is , according to SAHA, 2-10 times better value for money any of the other RoNS. If some of the VPT’s benefits are a bit dodgy, I hate to think how easily the other projects could fall over (for example Waterview Connection feeding a heap more traffic onto the already congested SH16).

On the bright side, more congestion on State Highway 1 northbound in the PM may well just encourage more people onto the busway. Now if only NZTA had bothered to build a bus lane through St Mary’s Bay to carry the 35% of people at peak times passing through the area on a bus, instead of five general lanes of traffic and absolutely no bus priority at all (even though this is meant to be part of the Northern Busway).

11 comments to Shifting the problem, not solving it

  • Ingolfson

    “I do wonder whether, in the cost-benefit analysis of projects like the Victoria Park Tunnel, all these negative travel time impacts are taken into consideration as well as the positives.”

    I would expect that they modelled that. Though I have no idea whether it ended up in the BCR calculations. There probably isn’t a clearly defined network extent that you have to include… would be hard to put a good figure on it. Maybe you could relative-ise-it – “You shall look at the effects on all of the network, on all routes branching away from your project, until any individual street / route carries X% or less of traffic of the 100% at your project site, and only then you shalt be allowed to stop looking at upstream and downstream effects”. Of course depending on how you set X, the network could be quite wide.

  • The problem is that this is a well rehearsed move; each time the choke point is moved down the road it suddenly becomes the next urgent point that must be ‘fixed’. Never is there any more intelligent approach to the congestion problem than building more road space. No full system approach, no consideration of managing demand, especially through the proper funding of decent alternatives, always the same answer to any question; throwing yet more fuel onto the fire.

    NZTA and its partners in the auto-highway complex don’t address congestion they exploit it to justify their spending. Congestion, or even just the idea of it is NZTA’s justification for existing, certainly for being virtually only a highway funder. To them congestion is by definition a scarcity of road width never a superfluity of vehicle traffic. To a man with a hammer every problem looks like a nail.

    To them all driving for every purpose is a priori good and valuable; never can it be wasteful or inefficient, or even destructive and ruining. All things it can be. Never could a different mode of travel be more desirable and therefore deserving of encouragement. Well not in sufficiently meaningful ways.

    The big game that they are building up to is insisting from their models that a vast, cripplingly expensive, and place ruining third road harbour crossing is needed. As a direct result of funnelling as many vehicles as possible through the CMJ towards the bridge they will announce that by some act of god that this demand must be meet with Tarmac. Not so.

    Build the missing mode across thie harbour first and see what happens to demand. There are 12 traffic lanes already across here and nothing else save a few desultory ferries. It is a big break in the RTN network. Fix that first, done properly and many will choose that mode and take pressure off the already vast road network and parking system. How can I be so sure that this will work? Because the incomplete busway is bursting at the seems despite all that is sub par about it.

    MoT/NZTA were wrong in their as pessimisism about that project as they are about many other PT projects in Auckland (see the MoT’s hatchet job on the CRL) because they suffer total capture by their habitual provision of nothing but driving amenity and the unsophisticated and illinformed prejudice of the current government. And because they don’t even seem able to understand their own data that shows that their vehicle growth models are wrong and reflect a different time’s patterns than the one we have been living through for around 5 years now.

    Perhaps they need some new blood in these agencies……

    • Ingolfson

      “The big game that they are building up to is insisting from their models that a vast, cripplingly expensive, and place ruining third road harbour crossing is needed.”

      Actually, my perception of NZTA is that many are well aware that the only argument for a new road crossing over the Waitemata is the aging-ness of the old Harbour Bridge, and that it doesn’t nearly merit building something for many billions in the forseeable future.

      However, if the boss is giving you a clear direction with his stick, then you go where he points, and hide your criticisms in between the lines of your reports. At the end of the day, nothing beats a government giving the right directions.

    • Andrew

      Just to be pedantic, it’s not 12 lanes across the harbour, it’s 13. Thirteen glorious lanes.
      And you raise a good point – NZTA’s modelling places the the assumed economic productivity of boy racers above that of bus-riding bankers (and workers of all other professions using PT).

  • Grum

    The tail back did not reach back to Gilles prior to the Vic Park Project, more like Mt Wellington from my experiance.

  • Malcolm M

    Local government should actually form the strongest opposition of RoNS. While the first impression would be that RoNS roads would whisk the traffic away from local roads, it will actually do the opposite. For every new journey on a RoNS road, much of that total journey would be on a local road. In cities this means additional congestion on local roads, for which the government won’t contribute any more. In rural areas it will mean more large trucks pounding the pavement of local roads, and possible demands from the trucking industry to increase mass limits without providing the funds to strengthen road foundations.

    • Also all those milk tankers are on local roads…. no RoNS goes to the farm gate. The whole thing is nonsense. And repair when delayed become reconstruction which costs a magnitude greater. It’s worse than false economy; it’s pissing money away which is desperately needed to be spent now or we’ll just have a bigger bill later. Ruinous.

  • Louis M

    I was thinking along similar lines to this post. Why is there so much obsession with a new harbour crossing? There would be no point in adding a whole lot of lanes across the bridge only to merge back on to the motorway on the other side. For it to have any benefit you would then have to add a couple more lanes for a considerable distance up the northern motorway.

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