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Another flawed congestion report

Every year TomTom produce a report about how much worse congestion is getting in Auckland, and every year the media lap it up – usually without looking at the flawed methodology of the report. So it was the NZ Herald yesterday:

Auckland’s roads are so congested commuters are spending an extra 45 minutes a day – or four working weeks a year – stuck in traffic.

A new report has revealed the country’s congestion is now worse than Hong Kong with the time spent on Auckland’s roads doubling in the space of three years.

TomTom has released the results of its Traffic Index 2017, an annual report about traffic congestion in cities around the world.

Auckland is ranked as the 47th most congested city on the planet, worse than Hong Kong, which has a population of 7.2 million.

Auckland’s level of congestion has risen from 33 per cent of extra travel time in 2015 to 38 per cent in 2016.

Drivers in New Zealand’s biggest city now spend an extra 45 minutes each day stuck in rush hour traffic, the equivalent to 172 hours, or four working weeks in a year.

As we’ve noted quite a few times before, the way in which TomTom derive their congestion “scores” is pretty meaningless because it focuses so much on comparing travel times between peak and off-peak, rather than actually looking at the overall average travel times for different cities.

We’ve unpicked this methodology before, but perhaps the best explanation of how stupid it is comes from Jarrett Walker, looking at “Urban Mobility Report” produced by the Texas Transport Institute using a very similar methodology to the TomTom report:

The technical core of the argument is simple. TTI’s Travel Time Index, one of their more quoted products, is a ratio of peak congested travel times by car against uncongested travel times by car. In other words, travel times are said to be “worse” only if they get much longer in peak commute hours than they are midday.

This ratio inevitably gives “better” scores to cities where normal uncongested travel times are pretty long — in other words, spread-out cities. Here’s the CEOs’ critique of how the TTI compares Charlotte and Chicago:

Now it seems complete nonsense to say that Chicago, with an average travel time of 32.6 minutes has worse congestion than Charlotte, with an average time of 48 minutes – but that’s exactly what’s happening here. Furthermore, the methodology completely ignores how an increasing proportion of trips taken by rapid transit, walking and cycling aren’t affected by congestion. Jarrett Walker again:

The journalistic spin that TTI itself recommends is that non-car modes matter only if they reduce congestion, and that congestion remains the primary measure of urban mobility.

What’s more, TTI’s suggestion that public transit directly reduces congestion is actually quite fraught, and many transit experts, including myself, steer away from it. Transit certainly creates alternatives to congestion for individuals, and the resulting benefit to individuals can be aggregated to describe society-wide improvements in both productive time and personal/family time. But those calculations are much more clear and direct than any “transit benefit to congestion” overall. That’s because newly freed, high demand road space tends to induce new car trips.

Most transit projects are not trying to reduce congestion, or not all by themselves. If congestion reduction is your goal, you need a combination of transit and market-rate “decongestion” pricing for motorists. For most advocates of transit in the context of compact sustainable cities, the goal is not to reduce congestion but to give citizens options to liberate themselves from it.

This is why it’s so important we invest in a greater range of transport options and particularly ones that are able to move a lot of people reliably and not affected by traffic congestion. Sure not everyone can or will want to use them but we’ve seen first hand in Auckland than when offered good options, many will flock to use them.

Perhaps the most useful way of using the TomTom report is not so much comparing across different cities – for the reasons best illustrated above – but more to track the same place over time. In that respect Auckland is seeing a pretty big increase in congestion over the past few years, up from around 100 hours a year to 170 hours a year. This is a pretty sad indictment, given how much focus the government has on reducing congestion and how much money they continue to sink into building more roads.

It will be interesting to see next year’s results and whether completing the Western Ring Route has made things better, or worse.

16 comments to Another flawed congestion report

  • Ricardo

    All I know is 5 years ago Papakura to Auckland on the motorway took 30 minutes, worst 45 minutes at 7:30 a.m in the morning. This daily morning trip now takes 1 hour 15 to 1 hour 30. And Friday afternoons going from Auckland to Papakura – can pretty much forget it, stay in town and grab a beer and dinner if you can’t get on the road before 2:00 pm.

    • I don’t think anybody disputes that Auckland has peak traffic congestion Ricardo, it’s just that they way they report it here is deeply flawed, especially the comparisons to other cities.

    • 01anthony

      Riccardo; Absolutely not – I also live in Papakura and used to drive on occasion to the city or new market. I started work at 8am and I would allow an hour. And this was back in 2007-2008.
      I call a massive pile of BS on your 30 mins @ 7.30am (5 years ago), unless of course you mean Sunday morning.

    • Or catch the train, it takes basically the same amount of time no matter what time of day. I don’t know about your timings, but you are spot on that congestion is getting significantly worse across the motorway network, and I don’t think anyone doubts it. Used to leave around 3pm on a Friday if heading south out of Auckland but now that’s even bad, started just taking leave on a Friday and enjoying a long weekend if I’m heading out of town.

    • mfwic

      Really? In the morning peak it used to take me 40 minutes from Ellerslie back in 1989. If you were getting in from Papakura in 30 minutes 5 years ago then you were doing very well indeed.

  • Nick R

    Wow, and even ignoring the flaws in the data The Herald reporting was just outright incorrect. Very poor reporting.

    The TomTom data doesn’t say Aucklanders spend an extra 45 mins in traffic at all, in fact they don’t even publish how long Aucklanders spend in traffic. All it says is that for a trip that takes an hour off peak, it would take 1h45 at peak. But most car trips in Auckland are far far shorter than one hour with no traffic, it’s hardly a measure of what Aucklanders actually do.

    They could have just said driving in Auckland takes 75% longer at peak times compared to when there is no traffic. No surprise there.

    • No surprises that the NZ Herald would report on flawed data. It’s not about news, it’s about clicks. Notice how articles throughout the day on their website/app move around and have heading changes based on how they’re interacted with throughout the day?

  • The real issue, and the one routinely ignored by all, is the spectacular and continued failure of the multi-decade, many many billion dollar, effort to ‘fix’ or ‘solve’ congestion through the entirely insane technique of incentivising more of it: Road building in a thriving city is traffic building is congestion building. The evidence of that is everywhere in Auckland and yet is not only still the policy, it is being pursued with renewed vigour and passion by an entire government bureaucracy with ever more billions, with less than no oversight from wiser heads, while little can be found for alternatives…

    What’s that definition of madness again? Doing the same thing, over and over…..

  • Dave B (Wellington)

    45 minutes a day stuck in Auckland’s traffic? You Jafas have it good.

    According to the Dom Post’s sensationalist reporting of the TomTom figures, Wellingtonians allegedly spend 20 days per year stuck in traffic. That’s a whopping 1.6 mythical hours per day, based on 300 working days per year!

    And apparently, “Wellington has one of the worst morning commutes in the world for a city of its size”.
    http://www.stuff.co.nz/motoring/news/90441247/tomtom-figures-reveal-how-much-time-we-lose-stuck-in-peaktime-traffic

    No doubt there will be a flurry of letters to the editor (+ comments to Transport blog) from the usual suspects, clamouring for MOAR ROADS.

  • John p

    According to this government the only use for transit is to reduce congestion. To an extent i agree. They wouldn’t spend a cent on transit if it didn’t.
    At the same time no one would use transit if roads and parking was clear.
    As for TomTom i didn’t think anyone used dedicated GPS navigation anymore.
    So wouldn’t Google have a better idea on congestion.

  • Lies, Damn Lies and Statistic!

    The bottom line is Auckland (and all cities) need less cars with more people per car. Most of the Tom Tom cities are dominated by driver only vehicles – 2 out of 3 Auckland commuting vehicles are driver only without any passengers – 79% of travel is by car – only 4% by public transport (http://www.transport.govt.nz/ourwork/tmif/travelpatterns/tp002/). The percentage in cars and driver only percentage have not changed in a decade despite various intervention attempts.

    Governments at all levels have failed – infrastructure takes years/decades to build.

    At Localift we think communities have the power to improve the situation. Our new smartphone app allows anyone to arrange free and flexible carpools for travel to work, schools, sport or any activity where you share a common destination with people you already know. Uber has trained people how to use smartphones to arrange transport – we hope Localift will make it easier at a grassroots level for people to travel together – rather than wait for more ineffective top-down schemes which have failed to deliver any measurable benefit.

    Localift will not solve all of Auckland’s transport issues – but we think Localift and other people/local community led initiatives can help. We’d love you to try it and share your feedback. http://www.localift.co.nz

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