Is Auckland abnormally congested?

I occasionally hear people bemoaning that Auckland is one of the most congested cities in the world, or at least one of the most congested cities for its size.

I’ve previously taken a look at this from a few angles – looking at trends in traffic delay in Auckland and average commuting time in large cities around the world. Auckland looks pretty good on the latter measure, which kind of belies the “most congested city” rhetoric:

Avg commute times in large cities

For another look at the same issue, we can take a look at data on traffic delay in cities across New Zealand and Australia.

Helpfully, the Australian Bureau of Infrastructure, Transport and Regional Economics (BITRE) publishes data on the cost of congestion in large Australian cities. They measure congestion as the amount of traffic delay that could feasibly be avoided without reducing the overall value that people get out of travelling.

Unfortunately, comparable figures aren’t available for New Zealand cities. The Ministry of Transport tracks delays in traffic, but doesn’t make monetised estimates of avoidable congestion costs. However, it isn’t that hard to make a reasonable estimate, if you combine MoT’s traffic delay statistics (average delay of 0.52 minutes per kilometre in March 2014, but less in the November survey) with their data on the total amount of vehicle travel in Auckland (12.7 billion vehicle-kilometres driven in 2014).

Following BITRE’s approach, I’ve assumed that avoidable congestion is about 55% of total delay – reflecting the fact that many people prefer to travel even on congested roads. I then monetised the total delay-hours using NZTA’s standard figures for the value of travel time (around $23.40 in 2015 dollars) and converted between Australian and New Zealand money. After mixing in some data on city population in Australia and New Zealand, I got the following chart:

Aus NZ city population congestion costs chart

Each individual point is an observation from a single city in a single year – so it’s possible to see how congestion has evolved over time in each city. We can immediately see three important things from this chart.

The first is that Auckland is right on the trend-line. We have the congestion levels that you’d expect to see in an Australasian city with 1.5 million residents – right between Adelaide and Perth. So once again, there are no signs that Auckland is particularly exceptional in the traffic congestion area.

The second is that congestion is a nonlinear phenomenon – it increases faster than city size. You can see that in the upward-sloping trendline fitted through the points on the graph. On average, in this sample of cities, a 10% increase in population is associated with around a 13% increase in congestion levels.

What that means is that new residents entering the city experience the average congestion levels in the city – 10% of that 13% increase – and also have a (relatively small) negative impact on congestion for existing residents – the remaining 3% increase.

The third is that, setting aside the average relationships across all of the cities, individual cities appear to follow slightly different trends. For instance, while Perth and Melbourne have followed the trend-line pretty closely, there seems to be a steeper relationship between congestion and population size in Adelaide and Brisbane.

That suggests that urban policies – land use, transport investments, etc – can enable some cities to grow in more or less efficient ways. Which specific urban policies are better or worse is a bit of a vexing question – but there does appear to be something there.

What do you make of the data on congestion costs in Australasian cities?

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36 comments

  1. I would (never!) criticise real cold hard large-n data with anecdote, but…
    To work in the CBD and have a <25 minute commute door to door you'd have to live basically in Eden Terrace/Herne Bay.

    1. Indeed, but for a start this is an average figure. Half the commutes are longer than 25 minutes. Secondly it covers all commutes for all job locations. Given just under 25% of jobs are in the central area, 75% aren’t. There are plenty of people who travel only five or ten minutes to a local job.

  2. Annecdotaly, working in Sydney, Melbourne and obviously Auckland each month (averaging a week or so in each), I find Auckland the hardest city to commute across, with Melbourne second and Sydney the easiest. What is noticeably different is that traffic in both Australian cities actually moves, whereas in Auckland the motorway becomes a parking lot at certain hours. It’s also noticeable that both Australian cities have motorways with consistent lanage, i.e 3 all the way, not 2, 3, 4, 2, 3 as we get here which contributes immensely to congestion. Traffic simply doesn’t flow in Auckland, and we should all be asking why NZTA and the Council aren’t putting efforts into creating consistently laned corridors (which incidentally would help buses too)..

    1. 99% of driving congestion is driver behaviour, not asset shortfalls
      Watch the inefficiencies at every green light
      Watch the inefficiencies at every onramp
      They add up.

          1. For some reason your comments remind me of Bertolt Brecht’s poem on the 1953 uprising against the communist East German government:

            After the uprising of the 17th of June
            The Secretary of the Writers’ Union
            Had leaflets distributed in the Stalinallee
            Stating that the people
            Had forfeited the confidence of the government
            And could win it back only
            By redoubled efforts. Would it not be easier
            In that case for the government
            To dissolve the people
            And elect another?

            Only I suspect that you’d mistake Brecht’s satire as a serious policy recommendation.

          2. Easily done. Stop over-enforcement of speeding. Start ticketing people for failing to keep left, queuing too far apart (“inconsiderate driving”), not indicating when merging, driving down a non-clearway left lane then cutting over when there’s a car (“inconsiderate driving”). Hammer it with publicity “don’t drive like a dick.”

            In five years, we can cut out road building budget by 90%

          3. > Stop over-enforcement of speeding.

            You’d be doing well to get anywhere close to the speed limit on an Auckland motorway during the peak, let alone be able to speed. People being concerned about speeding seems highly unlikely to be a cause of congestion.

    2. Have you noticed what else Sydney and Melbourne have that Auckland barely does? Yes that’s right full urban rail networks, and trams, buses and ferries… but especially those separate rail networks…

      1. note where sydney is on the graph , a full 10 min more travel time average and a smaller area than Auckland , doesnt look good for trains , but we both know that isnt the issue. the issue is the population of sydney is stuffing up the relative comparison , like most of the other cities listed too. so its almost meaningless

          1. Yep Sydney covers three times the area of Auckland and has a little over three times the population. Density wise Auckland is only slightly less dense.

    3. Anecdotes are nice, but the hard data suggests that Auckland isn’t unusually congested for a city of its size.

    4. You clearly have never lived in Melbourne or Sydney, or haven’t been on the motorways in rush hour. I’ve lived in both, and believe they’re just as congested if not worse than Auckland – with the added ‘benefit’ of paying tolls at the same time. Most visitors never leave the central areas and go out to the suburbs where it’s bad.

        1. Nice Patrick, the question was for observations, I answered based on regular experience. Stop the belittling stuff, it is more telling of your character than anything else. You need to get out and travel more. Those of us who do so for our jobs see some things (admittedly anecdotally) that often cast doubt on many statistics, which as we all know can be angled to prove anything.

          1. The question was “what do you make of the data?” not “what are your unsubstantiated opinions?”

  3. I wonder, if it is possible, if presenting congestion data might be better as km/time taken (I.e velocity). Some of the cities you present the data on have higher population than Auckland but are smaller in size. Also presenting cities like Sao Paolo etc is not really a valid comparison. Yes, I expect we are going better than some third world cities but would it not be better to compare us to similar size and GDP cities? I think that would be a better comparison and give us an idea if we are underinvesting in PT. Just a thought.

    1. I agree. Delay per km seems to be a slightly more elegant way of looking at it. This can then be linked to the (much disliked here I think) level of service. I have always found it useful to be able to tell people that for the worst 5 km of their route to work they have a LoS “C” even though they crawl for around 300m of it which makes it seem much worse.

      1. There are two factors at play here (at least). Delay per kilometre is one, perhaps best considered a measure of the intensity of congestion once you are exposed to it. But the other is the exposure rate, how much of that congestion do you experience? For the latter the length of journey is important too.

        If I have ten minutes of delay per kilometre, but I only drive one kilometre them my “congestion” adds ten minutes. If I have five minutes of delay per kilometre, but I drive fifteen kilometres, then my congestion adds seventy five minutes!

        Does the latter trip have half the congestion, or seven and a half times?

        This is important because some cities have relatively minor traffic issues, but very long commute lengths. I imagine places like Houston fall into this camp, I’d expect Los Angeles too. A land use-transport system that makes you drive long distances is as much a problem for congestion as one that has busy roads.

    2. In the congestion costs and city population chart, BITRE and I have estimated congestion costs by multiplying together the average vehicle delay per kilometre travelled by total vehicle-km travelled in each city. So it’s implicitly a measure that reflects both the severity of congestion and total exposure to it.

      And yeah, Auckland doesn’t seem to have a lot of it, comparatively speaking. Right on the trendline!

    3. I disagree, urban form matters as well.

      If you’ve forced your city to be a pancake with zoning laws then your delay per km won’t be that high, but commutes will be quite high (as people have to travel many km).

  4. What will the SHA’s do to this? Will there be work near the SHA’s? Will the transport be available when the SHA’s begin to be occupied or only 20 years after they have established the use of the car?

  5. There is an obvious pattern in the data. The more public transport a city has the more congestion they get. You’re welcome!

    1. The correlation I’m seeing appears to be very close to (shock horror) population, but it does quite closely align with PT, although some might argue Melbourne’s PT is better than Sydney’s, and Adelaide’s is better than Auckland’s.

  6. The first chart compares Auckland to cities that are many time larger. It should benchmark to other cities of similar size instead.

    The second chart of congestion cost is for total population. It would be more useful if the chart is congestion cost per capita.

  7. If its not congested then we don’t need public transport to fix it. So instead of $3B for the CRL we can buy a dozen new regional hospitals. Or anything really…

    1. Public transport isn’t just there to fix congestion, or even allow people to opt out of congestion. It also allows improved environmental outcomes and a pleasanter CBD. It provides more freedom for those unable or unwilling to drive. It allows cities to waste less land on roads and especially parking. It improves safety markedly, especially if it’s in a exclusive grade-separated right-of-way.

      That said, Auckland traffic is congested, it’s just that most of those other cities are too. But many of those other cities have congestion-free options that allow people to choose not to participate in congestion if they don’t want. That’s what Auckland should aim for. And luckily, that’s something that the CRL will be a big step toward achieving.

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