Like with public transport patronage, I keep a close eye on what are happening with traffic volumes on the motorways thanks to the monthly data released by the NZTA. The data doesn’t cover the entire motorway network but it does cover a number of key locations on it that can help to give an indication of what’s happening. I think the picture painted by these figures is extremely interesting. The sites we get monthly data for are:

  • Wellsford
  • ALPURT (the Orewa to Puhoi toll road)
  • Harbour Bridge
  • Upper Harbour Bridge
  • SH16 between Royal Rd and Hobsonville Rd
  • SH1 at Panama Rd
  • SH20 between Puhinui Rd and Massey Rd
  • SH1 at Drury
  • SH1 at Bombay

Excluding Wellsford, here are the six sites that we have the most data for

14 Feb - Motorways

There are a couple of things interesting going on here. At most sites the traffic volumes continue to remain fairly flat and in the case of the Harbour Bridge the annual figure remains lower than it was over a decade ago. Another interesting trend with the Harbour Bridge is that the annual figure is now bouncing up and down between 150k – 160k per day (it peaked in 2006 at 169k). However you see a clear change in the SH20 site. This isn’t surprising as in recent years there have been significant extensions and changes to that motorway including the opening of the Mt Roskill extension in May 2009 followed by the Manukau extension to SH1 and Manukau Harbour Crossing duplication in August 2010.

The changes can be shown even clearer by indexing them to Feb 2010 which is the earliest the SH20 data is available from.

14 Feb - Motorways indexed

You will also notice that ALPURT has shown growth. Unfortunately what isn’t clear is if this is a result of total traffic volumes along the route growing or people becoming more comfortable with paying for the toll road and so a higher percentage of people choosing it over the free route. The NZTA previously to recorded vehicle volumes at Hatfields Beach would have allowed that comparison but stopped doing that at the start of last year when they handed the road over to Auckland Transport.

As mentioned, the graphs above don’t include all of the collection sites reported on, the ones missing being on SH1 North of Wellsford, on the Upper Harbour Bridge and on SH16 between Royal Rd and Hobsonville. I haven’t graphed them due to how low the traffic volumes are in the case of Wellsford and how little data there is for the other two (only two years worth). In saying that the data that is available is quite interesting in its own right.

SH1 North of Wellsford – Traffic volumes are very seasonal peaking over summer but overall they have been in decline since monthly figures began in September 07. This is quite important as we often get told that the reason behind the Puhoi to Wellsford motorway is to unlock Northlands economy. Both the SH20 and Upper Harbour Bridge sites are interesting as the annual figures show traffic volumes on those sections had been flat since 2003. The volumes over the Upper Harbour Bridge only started increasing again in 2008 after the Upper Harbour section of SH18 was completed while the SH20 site only started increasing in 2011 after the Westgate to Hobsonville section of SH18 was completed.

To me these figures show a couple of key trends. The motorways not widened or extended have shown little to no growth and in some cases volumes remain below what they were in the mid 2000’s. In the places where we have built motorways, vehicle numbers have been increasing. To me what this effectively points out is that changes traffic volumes are really just a reflection of what we’ve invested in, or in other words a case of build it and they will come. That might sound logical (and it is) but it also highlights the opportunity we have to determine just how much traffic is on our roads in the future. Build more roads like the current plans suggest and we’ll get more traffic.

Of course the opposite is true too, remove roads and traffic disappears with it. This has been shown quite well in Seoul, Korea where since 2002, 15 expressways have been demolished and more are planned. The most famous of which was in Cheonggyecheon where they removed an elevated expressway and ground level roads carrying over 150,000 vehicles per day and restored the original stream making a wonderful urban park in the process.

It went from this:


To this


And the outcome was even more impressive:

  • Traffic volumes dropped while bus and subway usage rose
  • There were increases in fish, birds and insects in the area.
  • Temperatures decreased and are on average 3.6% lower than other parts of Seoul.
  • It became a centre for cultural and economic activity.
  • And perhaps most interesting to the NZTA/AT, traffic speeds on other roads increased which is an example of Braess’s paradox

Now I’m not suggesting that we tear any existing roads down but more just highlighting that we have the ability to shape the city how we want it. If we don’t want traffic volumes to increase in the future that we should start by not building a heap more roads.

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  1. Plenty of elevated motorways we could remove, including the Hobson Street overpass (in effect a motorway), Victoria Park motorway bridge, and innercity streets that need reclaiming such as Hobson, Albert, Fanshawe, Quay Street, Victoria Street, K’Rd, Upper Symonds Street. Trouble is AT would never get any money from NZTA to do such projects. They’d get money at the drop of the hat if they instead proposed to build elevated expressways over the top of them all. NZ’s transport funding model reflects that of 1960’s USA when the Federal Government funded motorways 100% and everything else only partially or not at all. No wonder their cities are scarred by urban motorways, and why Auckland is rapidly cutting itself up even at an increasing and scary pace.

  2. Sure we can reclaim, but for who? Removing roads in the city will affect bus users most. Buses can’t use bus lanes if they can’t even reach them.

    I don’t think we should be building new wide roads like Mill Road or the crazy Lincoln road plan unless we are also building in strong PT links as well.

  3. Not sure if this is the best post for this news story from this morning’s Herald.. but it’s about an aspect of intensification which motorways are not just irrelevant, but, as Braess’s paradox shows, can be detrimental. (Thank you for that reference Matt.. Ari you really need to read it and stop to think before commenting.. it does *not* necessarily follow that removing roads affects anyone negatively, least of all bus users).

    Just look at the distribution of red and green circles here..

  4. Matt, your “build it and they will come” comment hits the nail on the head. The SH20 and Alpurt (what a horrible name, sounds like something a dog left behind that got stuck to your shoe) lines in the second graph epitomise this. I’m sure that the same will be seen once the west ring road is finished, they will come.(of course nobody will show the graphs of Staddard Rd, Maioro St et al. which will see traffic volume copllapses) I only wish the same approach could be taken to cycleways as I had a wonderful ride alongside the Northwestern this morning only to suffer under traffic light tyranny once I hit Newmarket and Remuera Rd. Great post. Cheers

  5. TBW, no it doesnt necessarily mean bus users will get affected ,but they very likely will given that more people take PT into the city in the AM peak. Just depends what changes are being made to the network.

  6. It is better than the elevated expressway, but the Cheonggyecheon stream doesn’t do much for me. The sheer walls on either side are pretty grim, like a watery anti-tank ditch. And the stepping stones are a bit twee. The photo here seems to be during some sort of festival and there are lots of people around. But Googling photos of the stream show it to be stark and underused at other times. I can’t imagine sitting there to eat my lunch. I give thanks that Auckland has plenty of spectacular natural open areas, and doesn’t need to create regimented “natural” spaces down the center of busy roads.

  7. I lived a few minutes from Cheongyecheon last year and have spent many years in the city before then. I can assure you it is not under utilised at all. It is extremely busy at peak times and well patronised round the clock. It also allows residents in the heart of Seoul megalopolis to enjoy the company of ducks, carp and other wildlife and have a pedestrian only walking route through central Seoul. There is no downside to this project. It sent nearby property values through the roof and rid the city of the awful, choked Dong Il expressway.

  8. Yup knock down the motorways and less people will travel. But why stop there. Close the hospitals and there will be less patients and no waiting list. Shut those schools down and there will be even less people travelling around, no truancy and no school drop outs. But these ideas only succeed if you see the effects as problems and don’t notice all the good things that also occur. When people travel around they do so despite the congestion because they derive benefit from their trip. They make money, have fun, visit their family and friends.

    1. “Close the hospitals and there will be less patients and no waiting list. Shut those schools down and there will be even less people travelling around”

      Oh for goodness sake! Don’t be childish.

    2. My point is you have defined traffic as being a negative rather than a benefit or a neutral impact. And the Braess pardox argument is flawed. It only holds when you assume some routes get a highly volume dependant travel time and some don’t. Its why we dont put a mix of fixed timed, volume dependent and free routes into models. In any case it doesn’t hold at higher volumes, Braess didnt know that, nor did he know what a paradox is.

      1. Traffic in an urban environment is a negative. Healthcare and education are positives.

        Also, if people are able to travel less and still meet there needs, or travel more efficiently (not in a car for this setting) then removing the freeway is not only neutral in travel terms but positive, as well as being positive in place terms.

      2. Braess simply pointed out that under certain conditions it’s mathematically possible that building a new piece of roads increases travel time for everyone. How often those conditions occur in real life is obviously a point of keen interest. I don’t think he made any particular claims about that.

      1. Yes and yet some people take the same simplistic view of traffic. Road capacity allows for more jobs to be provided in different areas which in turn create traffic. The anti-roads knuckleheads think that PT is a ‘perfect substitute’ rather than an ‘inferior good’ (both being defined in an economic sense).

        1. Pt creates more jobs closer to where people live reducing travel distance. Roading knuckleheads simply believe it to be an inferior product because most of our pt system is low end pt and our roads are lavish

          1. Not true. PT only works when it is accompanied by rules that prevent jobs establishing at locations away from stations. Some jobs then locate near stations and some jobs dont occur at all (a dead weight loss) or occur in another jurisdiction..

          2. and please, do tell me which jobs establish themselves in cities where it takes 30 minute to drive 1km to get on the motorway because everyone else is doing the same?

          3. Why would there need to be rules to force jobs next to stations? Businesses will naturally locate in areas where they have higher labour market accessibility and easier access from their client base. All else being equal businesses will chose to locate next to stations, if the service is useful.

          4. Thats why we have so many jobs popping up in Town, and at Newmarket, and Smales Farm, and Sylvia Park right?

            You only get jobs in the far flung locations like you suggest when you force them away from PT like we have for 60 years.

  9. Th

    That said, there is an old disused motorway flover/bridge right in the middle of the Auckland CMJ that would make a great park….anyone got $20mill kicking around? Also, I wonder why this wasn’t incorporated into the CMJ cycleway??

    1. I believe it was left standing when the CMJ was reconstructed because the costs of demolition were not justified by the benefits. Well, at that time there were no benefits as such – it simply wasn’t in the way of anything else so there seemed to be no point in the extra expense.

      Since then, of course, other ideas have been put forward such as you suggest. Personally I would like to see it become both a cycleway and a linear park. A long line of trees, shrubbery and flowerbeds would help alleviate the concrete canyon.

      1. By all means let’s use this embarrassment of NZTA’s (well an earlier incarnation) but don’t kid yourselves it’ll be like the Highline up there in the middle of the CMJ. It’s going to be a noisy and fumey experience on that disused off ramp.

        Still, better than leaving it there unused, and it does offer a link between that other motorway dominated cyclyeway now being built in Grafton Gully and the west side of town. And I guess it offers a somewhat surreal image: Cycling down the middle of the CMJ!

        More urgent is the conversion of one lane of Ian Macknnon Drive to make a proper connection between the northwestern and the GG route….

        1. I agree Patrick. I’d rather see separated bike lanes up Hobson, onto Pitt, and then right along K’Rd as the cross link. So people on bikes can access shops, cafe’s etc.

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