We have frequently raised concerns about projected future traffic growth, given that in recent years there has been an extended flat-lining of traffic growth. What’s perhaps most concerning about these projections is how they ignore what has actually happened in the recent past and how those producing the projections don’t seem to learn from past mistakes.

This isn’t just an Auckland problem. An article I came across recently looks at projections for a bridge across Lake Washington in Seattle highlights how stubborn the projections of growth are despite evidence to the contrary:

traffic-projections-678What’s crazy about this graph is how persistently wrong the projections have been – yet without any change to reflect the reality of declining traffic volumes over a 15 year period between 1996 and 2011.

Yet it’s not just a specific example of a bridge in one American city where we see these persistently wrong projections coming through. Let’s look at a comparison of official traffic projections across the UK over the past 20 years and compare those with what actually happened:

uk-traffic-projectionsIt’s hard to know whether these repeated mistakes are just accidental, ignorant or wilfully neglectful of reality.

Our own local example of this ignorance is in the traffic projections being used for the stupid Additional Harbour Crossing Project, where modelled traffic growth rates completely ignored recent trends and therefore were calculated from a base that was significantly too high:

This graph was from a year ago and in the past when I’ve posed it, there have been some that say “look it’s starting to rise again” but the reality is it isn’t. The most recent monthly data shows traffic have flat-lined and volumes are still less than it was a decade ago (monthly figures only started in late 2007).

AHB Monthly Traffic Sep 13

Similarly another frequent comment we see when this is discussed is to the effect hat the downturn is only due to the current state of the economy. However many economic indicators are pointing to the economy being much healthier today than it was a few years ago. Other indicators highlight that while on a per capita or percentage basis we might not be doing as well as in the past, on a total basis we are doing well. For example despite the percentage of people who are unemployed being higher than it was in 2007/08, in total there are actually significantly more people employed at the moment.

I suspect traffic projections keep making these mistakes because they are calculated using models with fundamental problems in them. They are generally designed to predict the future based on extrapolating our behaviour from some point in the past. That may have worked in the 90’s (and earlier) but it doesn’t work now and one of the key reasons is that we are seeing generational changes occurring with young people choosing not to drive as much as older generations. Yet while road models might be well over estimating vehicle trips, PT models have been doing the opposite. One of the best examples is Britomart where we exceeded the 2021 projected daily patronage in 2011.

Britomart Projection Numbers Graph

And even the Ministry of Transport in their response to the City Centre Future Access Study said that private vehicle trips were probably being overestimated.

MoT OIA docs - Modelling 1

When there are tens of billions of dollars of public money is riding on these faulty projections, it suggests we need a new approach starting with not believing the current projections.

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  1. Transport agencies have a massive incentive to keep producing these bullshit projections because they help justify projects that shouldn’t happen.

  2. The Government is ‘captured’ by departmental inertia, ideological ‘truths’ about human behaviour, and multi-billion dollar contractors.

    They’ve been able to ignore wet and smelly cyclists and assorted others, but now this blog along with several plucky politicians are shifting the discourse. If you want to hear the old mentality, listen to Sean Plunket’s interview with Julie Anne Genter. He ‘wins’, but only because he ignores the facts, like a car crossing in front of a train.

    1. Interesting comments in the linked post about how, in the age of electronic devices, 20 minutes in the car is wasted, but 40 minutes in the bus is useful – providing the bus is not a sardine tin. This suggests public transport should be developed with a high priority to in-vehicle comfort. (this has been the natural trend of the last generation anyway as living standards rise, with airconditioning now standard for example)

      1. And wifi, or whatever the current connection technology is…. Especially for systems that use tunnels.

        I am not confident that AT understand the value of this competitive advantages of Transit or are planning to ensure it is available AND market the bejesus out of it.

        1. Agree.. benefits of free wifi on PT all too easily forgotten / undersold. Especially valuable to overseas visitors not in possession of a local SIM card.

  3. Is it reasonable or helpful to focus our energies on organisations as the suspects.. “transport agencies”, “Government”, “departmental inertia”, “road builders”..?

    But isn’t it *people*, individually and collectively, who are the problem? Real change often only really happens in practice when people change.. i.e. when the current people in planning / engineering / political leadership posts leave, retire, die.. and are replaced by new people with new perspectives.

    Just look at the first two graph, can you really believe it was not the same people doing the same thing in the same way time and time again?

    Old habits die hard.

  4. I suspect the over optimistic misuse of these forecasts is because of the vested interests of the large roading industry along with the motor trade, both motor vehicle sales and service and the oil industry, who win with road construction and vehicle sales. These groups make up a fair bit of our economy albeit the non export side (though it is argued it helps exports by getting goods to ports) and all employ a lot of people.

    Similarly the same forces would rather see PT relegated to the shadows as well. And then theres the murky political donations side to the equation.

  5. And yet car manufacturers are reporting a boom in sales. I guess people must be buying cars to keep as mueseum pieces on their driveways. They must be buying fuel and pouring it down drains because every quarter the oil companies show another record profit.
    Was it me or did I just imagine all those cars on the bridge this morning?

    1. The apparent boom is quite a bit of catch up from the GFC, when new vehicle sales were pretty much at an all time historical low. The VKD is of more importance than actual car sales.

      1. Put it this way. A person who drives their Range Rover Sport 1,000 km per annum is creating far less of a problem than a Prius owner who is doing 10,000 km per annum.

    2. You are mixing up car ownership with car usage. Also I doubt many young people are buying brand new cars that would be the older generations who are still travelling a lot by car.

      I have a car for our family but I hardly use it. I may drive it twice a week and my wife maybe 5 times a week. The Netherlands (527) has a slightly higher car ownership per capita than the UK (519) (http://en.wikipedia.org/wiki/List_of_countries_by_vehicles_per_capita) but the Dutch dont drive as many kms per capita as Britain. Because of course they cycle a lot and use PT.

      The developing world is still buying a lot more fuel every year and a lot more cars. Therefore yes, oil companies continue to make more money plus of course oil prices are going up. These figures for driving are all for the developed world where peak car has occurred.

      Yes there were cars on the bridge, I saw them from the ferry. Were you able to judge with your naked eye whether there were as many cars as there were 10 years ago? Because carefully gathered data from the NZTA suggest that there are fewer cars driving over the bridge at peak times. Matt has explained this very carefully and in detail in past posts.

    3. Phil car sales are not an indication of anything much except that industry’s viability as most purchases are replacements; thousands of cars are trashed each year, and after years of poor sales this bounce is simply catch up. Only if the total number is growing AND if they are being driven more would your stubborn opinion be supported by the facts. And they aren’t and they aren’t.

      So yes, cars are increasingly being stored more and driven less than before.

      More lies without evidence too; oil majors are struggling to be as profitable as in the past, and oil consumption outside of the developing world is not rising.

      As a troll you are persistent but not very effective; bless.

    4. On oil price, production costs and volumes, and oil company profitability:

      “Oil boom not translating into higher profits or output”

      “Profits Plummet for Big Oil Companies”

      “Despite boom, oil companies struggling”

      Now this from Bloomberg:

      “The world’s biggest oil companies are failing to convert the highest Brent crude prices ever into record profits as production costs climb and U.S. natural gas prices languish.”

      The costs of extracting what is known as ‘unconventional’ oil, so called because of the elaborate efforts required to produce these fields, such as Tight or Shale oil are so high that profits are squeezed despite very high crude price. There is no such thing as ‘cheap’ Shale Oil. To use such a phrase is either to be intentionally misleading or an ignorant fool…. Which is it Phil?

      1. Patrick,

        Shale is suppressing the value of WTI crude which is the US benchmark. An improving US economy is creating more demand for transport fuels. What you buy has to be delivered. Increased productivity also means increased oil demand as factories run on power and plastics are made from oil.
        So with cheaper crude and higher demand for oil products is it hard for you to imagine refining margins are booming? I can tell you for a fact that US refiners are running flat out and are now exporters of oil.

        1. More selective information from our fan Phil, here’s what he misses out:

          1. The US has always exported refined product but it still is and will remain a net importer of crude, imports have reduced, true, because of two factors, increase in local production from Shale, and lower consumption, but it is the net figure that matters and it is nowhere near zero. Shale has not and will not make the US a net exporter of crude. As the US is not a net exporter to bring up refined product movements like it is significant to total supply is disingenuous or naive, and as you a self proclaimed expert in this field we can only assume that you are setting out to deceive.

          2. ‘Cheaper’ than when? Yes WTI and Brent, and Tapis and the rest are a little off their peaks currently and while daily, weekly, and monthly price movements are of interest to traders and gamblers it’s the longer term trend that matters to making infrastructure investment decisions. So compared to prices 10 or 15 years ago does it make any sense to use the word cheaper? No of course not. Crude is stubbornly over four times the price it was before the driving stats all started to head south.

          3. Will recent fluctuations in crude from the 100s to the 90s continue and lead prices back down to the levels that will get people driving again (even if this were the only factor) based on even more Shale oil. No because fracking is both very expensive to do (maybe needing >USD 80 to break even) and because of eye watering decline rates. Some increases in productivity at the well head accepted, but still there are those decline rates… Shale will be a busted flush this decade. Shale is a bump in total supply terms, a handy one, but not the white knight you insist. Proof? Where are the meaningfully lower prices from this boom? Where’s that $20 crude?

          4. Similarly an improving economy does show some lift in consumption over short periods and in some places (especially in the Shale states: they’re using a lot of diesel trucking and railing that Shale and those fracking fluids around!) but this consumption growth is still below pervious peaks and the curve is flat; even with a better economy the old model is gone. And this is the really good news; there is an increasing disconnect between resource consumption and economic performance (in the west); and we, the world, desperately need this.

          But you know all this don’t you Phil? You know better than to conflate refined product with crude, the former of course being derived from the later. You know that refineries are closing and many are struggling to make meaningful margins, but that anyway refining being profitable or not doesn’t prove anything about upstream total supply or profitability.

          So why do you bother, what is the purpose of this dissembling? Weird really.

  6. these graphs are great! I love seeing them all the time and how engineers keep using crazy projections hoping things will come right again.

  7. The main aim of politicians is to get elected and then re-elected. They do and build whatever they think the voters want in order to achieve that aim. Look at our Mr. Abbott. Catagorically stated that he would build roads and not urban rail thus torpedoing several urban rail projects and got elected. It is not the planners or the politicians that need to be educated. It is the VOTERS. You have seen effects like this happening with the CRL. Our Australian Rail Track Corporation (ARTC) repeats a slogan that says “each superfreighter takes 120 semitrailers off the highway”. That slogan is drawn out of my memory and so will not be exactly correct. What Auckland needs is a slogan that says “Each new electric train takes XXX cars off the road.” I will leave it to the locals to fill in XXX. You have seen how the CFN has grabbed public interest and so should a program to educate the public as to the way an efficient PT network will reduce traffic congestion.

  8. Edited: comment breached user guidelines:

    8. The editors decide what is acceptable. We reserve the right to delete comments and suspend accounts as we see fit. Grounds for suspension include:
    i. Obsessive arguing in a thread or threads
    iv. Use of multiple anonymous identities

    1. Phil, I realise you are trolling but it would be polite to respond to arguments put to you rather than just comment bombing.

      I will try again:

      You are mixing up car ownership with car usage. Also I doubt many young people are buying brand new cars that would be the older generations who are still travelling a lot by car.

      I have a car for our family but I hardly use it. I may drive it twice a week and my wife maybe 5 times a week. The Netherlands (527) has a slightly higher car ownership per capita than the UK (519) (http://en.wikipedia.org/wiki/List_of_countries_by_vehicles_per_capita) but the Dutch dont drive as many kms per capita as Britain. Because of course they cycle a lot and use PT.

      I realise these are inconvenient truths for someone in your line of work and that you are surrounded by people who think this is all nonsense. As history has shown many times, that doesnt mean it isnt true.

  9. Edited: comment breached user guidelines:

    4. General moaning about the blog and its editorial direction is extremely boring. If you there are things you like and/or don’t like about the blog then put it in an email to us, rather than a comment. Or find another space more to your liking.

    8. The editors decide what is acceptable. We reserve the right to delete comments and suspend accounts as we see fit. Grounds for suspension include:
    i. Obsessive arguing in a thread or threads
    iv. Use of multiple anonymous identities

    1. Tutut: ‘I don’t think the demographic of the age of drivers really is a reason to build roads or not.’

      Of course it is. Unless you think that road programs should have no regard to how many people are likely to use the finished road in future.

      If you admit that trends in car use are relevant to prioritising investment decisions, then such figures are highly relevant. Because the behaviour of today’s younger people is likely to be a predictor of the behaviour of everyone in future (assuming that some habits are stable through life**). Just like the rate of takeup of smoking by young people is relevant to predicting the future costs of smoking related health care.

      ** of course there may be behaviours where all/most people behave in a certain way when young, but all/most change as they age. Then the implications would be different. An interesting question is whether today’s drive-less young people will, as they get older, adopt the habits of today’s drive-more older people.

    2. ” I base this on people wanting to drive door to door”

      If your entire argument is premised by this statement then you need to prove it because the NEX would beg to differ.\

  10. I’m interested to see what’s going to happen to the real data once the baby boomers get to the point they are no longer able/motivated to drive. They are the highest (or second highest?) car km users. Has that sudden drop off (as that population bubble moves through) been accounted for in the projections? I’m going to take a stab at answering my own question – no.

    1. Greer, yes, the boomers [my demographic] are the drivingest group ever. They drive more than their parents and they drive more than their children and grandchildren. They are anomalous. Their habits will, in fact are, dying out with them.

      Unfortunately they are also all over the powerful decision making positions and, like our big fan Phil, just refuse to believe the facts no matter how obvious. They [we!] are also known as the selfish generation, the me-generation, and seem to largely prefer to believe what suits them personally rather than inconvenient reality.

      1. “They…just refuse to believe the facts no matter how obvious”

        An entire generation characterised by an unsubstantiated generalisation. Would it be too much to ask for some sort of statistically valid reference that supports your statement?

        1. Come on MFD, obviously all discussions of generational trends are generalisations. It doesn’t mean everyone of a certain age is identical. I, for one, am an age group traitor. And of course there are driving fanatics in other cohorts (boy racers, for example). These numbers only show tendencies. But the stats are clear, again see Lennarts Netherlands chart above. The numbers are not controversial. And while the various age groups are sort of arbitrary the main purpose of the research into these trends is for working out how to sell and market to these segments which does give it discipline, ie if they’re wrong, business models fail.

          Also it’s not personal, no need to feel insulted, these analyses don’t say any group is better than any other, they just try to be precise about tendencies. Especially, as I say, in order to exploit them commercially. Have you not noticed how many ads for certain types of cars go to great lengths to associate the idea of freedom with owning whatever brand of vast older male vehicle they’re plugging. Lots of shots of single vehicles powerfully flying along through empty countryside- they’re aimed at us. That these cars will mostly be driven in congested city traffic does rather make these images absurd, but of course that’s how advertising works; it appeals to subconscious beliefs not conscious reasoning.

          1. The generalisation at issue is your contention that boomers refuse to believe the facts, no matter how obvious. Please explain what facts you are referring to, how you reach the conclusion that a group of people refuse to believe them and how this group is representative of all boomers. I’m not insulted, just fascinated at how individuals reach sweeping generalisations based on the flimsiest of “data” and bizarre conclusions when reference to Occam’s Razor and a bit of rational unbiased thought suggests that there are better explanations.

            Moving on from your more egregious claim to that of high driving being a “habit” of boomers. How do that stats show that this behaviour is habitual? Yes, the stats are clear, but do you understand what they mean? The chart you refer to above shows the change in driving from 1995 to 2012 by age group in the Netherlands. Since no units are given I guess we should presume that they are km per person per year. No baseline is given, no numbers for each group and no motives can be deduced from the graph. My experience of number of km driven per year is that it is largely a function of the distance between one’s house and one’s place of work together with the availability (or lack thereof) of effective alternative transport. Changing job location or residence location changes the distance driven per year. Occam’s Razor.

            Let’s look at the various claims above that overestimation of traffic demand is due to a bunch of engineers engaging in habitual behaviour. An alternative explanation is that these projections are codified extrapolations, ie there is a standardised methodology or procedure that those doing the projections must follow (in much the same way that the number of parking spaces by building type is codified). Occam’s Razor. My experience in engineering is that these codes are a matter of managerial decisions and policy rather than a conspiracy by engineers to wifully disregard facts. As such the relevant decisions will have been made by a few people in each transport agency in each country.

          2. Ok let me be more precise as you are clearly aggrieved by this thought.

            It is likely that every age group is more or less delusional about all issues to some degree, I am not claiming that any generation is more susceptible to wishful thinking than any other. But that specifically when it comes to transport choices and desires this generation, because they themselves are the ones who drive the most and value the act driving the most, tend to insist more than others that their experience on this matter is universal, no matter what the data says.

            That’s all, no insult.

            And also yes, driving is a habit. It sure is here in Auckland. I know it was a habit I was in, typical of my generation, I used to drive everywhere for everything, and rant and moan about other traffic and a lack of perfectly placed and always available free parking everywhere I wanted to go. I still drive when it is the best option but now only then, and not as a matter of reflex. My personal VKT is down by about 75% from this period due to adding transit and active travel to my movement habits. Anecdotal I know but as Auckland VKT is flat while population is rising we know there are other people with different habits too.

            Of course it is hard for many people in AK to change the always drive habit even if they want to (and of course no one has to) because of the appalling provision of amenity supporting anything much other than driving here. Hence, you know, this site. Great news is this state of affairs is improving. But slowly and fitfully.

          3. I think MFD is also confusing a genrealisation of a group’s behavior with an assertion about people’s behavior. For example in 2008 and 2011 New Zealanders back a National Led government, but not all voters did. Exact same thing here.

          4. “I think MFD is also confusing a genrealisation of a group’s behavior with an assertion about people’s behavior”

            On the contrary, I was asking for a rationale to support the generalisation, to whit, ” boomers refuse to believe the facts, no matter how obvious”. Let’s perform some simple tests, shall we?
            Women refuse to believe the facts, no matter how obvious…looks like BS to me
            Blacks refuse to believe the facts, no matter how obvious…still looks like BS

            Let’s parse the language used, shall we? No matter how obvious…seems extreme and stretches credulity.
            Let’s examine it from a methodology standpoint…how would one determine whether this alleged refusal was as the result of being presented with the facts and a refusal of a demand to believe them, a mistaking of facts for fiction or ignorance of the facts or even not realising what the relevant facts are?

            No…looks like BS to me but I am a rational person. Here’s a challenge for you Sailor Boy; Provide some corroboration to support the validity of the generalisation (Patrick has carefully skirted the question) and I will accept it. To make the challenge easier shall we say demonstrating that >50% of the baby boomer population refuses to believe the facts, no matter how obvious” constitutes a valid generalisation. Bear in mind the greater context of data-driven conclusions if you would, please.

          5. Ok, I see your point.

            Can I ask if you would still disagree if rather than “facts” it were “the facts about the driving habits of other generations”? There is obviously no way that I can quantify this, and nor can Patrick, but I would say it is relatively obvious from reading the Herald that even if not a majority, a large minority would not that description.

          6. MFD you are mischievously stretching what I said by ignoring the context: as I clarified above this is all in terms of driving data. Not about everything. And yes generalisations are just that; general. Really this is getting silly.

          7. “but I would say it is relatively obvious from reading the Herald that even if not a majority, a large minority would not that description.”

            You really believe that a self-selected sample that chooses to vent in the Herald can be taken as representative of the whole group? Have you no concept of statistical theory? How do you deduce the generation that these contributors to the Herald belong to? How do you know that what is stated in the Herald is really what the person thinks and not just some provocative nonsense written in semi-drunken stupor?

            Here’s some helpful advice: don’t take what is written in the Herald too seriously. Their prime objective is to sell advertising. I am going to indulge in a generalisation of my own – it’s a poor quality paper and getting worse. I can provide supporting evidence if you want but it won’t be via this blog

    2. Greer, for the record may I make it clear that Patrick does not speak for me (another baby boomer), any more than I would be so audacious as to pretend to speak for him. He and I probably disagree on just about everything, but that’s OK, otherwise the world be a pretty boring place.

      Back on topic, I’m no statistician but even I know that past trends are not a reliable guide to the future, despite popular belief. There are simply too many variables. (I’m sure that Stu, as an economist, could explain that far more eloquently than I). As an analogy, I’m tempted to suggest that if the word “traffic” in the post heading were replaced with “IPCC”, the graphs relabelled and a few relevant words changed in the text then you would get the point. But I won’t suggest that; it might be safer to use “managed funds” as the analogy.

      1. Yep, you’ve hit the nail on the head there Jonno 1. Climate change is just a make work scheme for scientists. Thankfully ‘everyone’ knows better than that.

      2. Jonno I agree that disagreements on matters of opinion are great, vive la difference, but please can you point out which of the facts in my comment above you consider to be an opinion?

        Boomers ARE the drivingest ever group, this is a fact across the OECD, probably a little different in the developing world as these places came to mass driving more recently, please look at Lennarts chart above.

        Clearly earlier gens didn’t drive as much before the post war driving boom, and there is really good and clear data that shows subsequent gens aren’t driving as much. Not an opinion but a fact. And as boomers age and move out of the work force they are taking their habits with them. This will continue to the grave. OK that is a projection and not yet totally proved, but it is already happening.

        Also the subsequent generations are not driving as much as this group even as they age and have children etc. No one loves to be behind the wheel as much and as consistently as this lot. For them driving equals freedom, unlike the Millenials especially who are more likely to find it oppressive.

        1. Patrick, the second para of your 4pm yesterday. I know no-one (among my personal baby boomer friends/acquaintances) who fits that description. I can think of a few public figures who might fit it, the most obvious local example being our esteemed mayor, but as a generalisation it’s way OTT.

          As for driving kilometres, no argument there, we oldies have more time to get out! Just checked that in the last 12 months my wife and I each drove almost exactly 7000km. That surprised me as I thought she drove a lot more than me doing her nana thing. Then I realised that while her driving is local, mine is mostly long-distance but less frequent.

          1. Be careful Jonno, don’t conflate discussion about generations, which over time cover all age groups, and age group behaviour, which over time covers all generations!

            Boomers are a generation; usually defined as people born between 1946-64, and indeed are now getting older, but of course they weren’t always. So there are two separate issues here: How does this generation *generally* behave, plus how do older people *generally* behave?

            The answers for our generation are contradictory. We are the drivingest generation ever through all age segments, driving more than our parents and our offspring at the same ages, in general. But we also exhibit a typical slow down as we age, associated with retirement.

            And from 2011 every year for the next 18 years another bunch of boomers hit 65, the nominal retirement age…. I look forward to watching this change be reflected in changes in driving stats. The younger generation’s travel tendencies will increasingly dominate the figures, and so far, this clearly has shown up as consistently lower VKT across the whole of the OECD.

            A per capita drop in NZ but a huge gross drop in the US and Europe.

            I guess its hard to rack up the Ks on a cruise ship or in a rest home….

          2. 7k per annum is actually not high in the grand scheme. I’ve been averaging 17k or so for the past 5 years. 15k per annum leases are the most common and these days 20k pa leases are probably commonplace.

      3. Hang about. If we are supposed to ignore any trends in driving of different ages then why are we building roads to support traffic using trend related data (which actually looks to be inaccurate)? You can not have it both ways. What is it to be?

    3. Well it is starting to be noticed that a change is occurring. The NZTA has cut from the economic evaluation manual the ability to use a traffic growth figure and so any traffic growth now has to be justified (but our models to do that are still crap). Also they recently put out to tend research looking at travel trends of young people noting that trends are changing.
      How long it takes for the realisation of the changes to flow through to some of the old school engineers and planners is a different story though.

  11. What would be the effects of making Public Transport Free in Auckland NZ by using our annual capital spend on Capital roading expenditure as the source of revenue for it.
    Roading infrastructure maintenance needs to be increased to cope with the greater number of maximum vehicle mass loads that are causing catastrophic wear and tear on existing roads not designed for these loads and the control of these vehicles use of the roads needs to be better controlled. (The changes needed to support the vehicle mass change needs to come from Central Government as the individual local Authorities do not have the budgetary base to sustain a lot of the through traffic)

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