Every weekend we dig into the archives. This post was first published in November 2011.

It has been frustrating to see the assessment of the City Rail Link’s benefits become so politicised over the past few months. You would think that something like undertaking a cost-benefit analysis of a transport project would be a fairly objective task, but as we have learned there are so many assumptions made when assessing transport projects – that the objectivity of the process has really become something of a myth. Something as seemingly benign as the different discount rate used and a different timeline over which to measure a project’s benefits can have a massive impact – as seen when comparing how the UK and New Zealand assess benefitsBut that’s not the only area where there’s disagreement and subjectivity. There’s debate between the parties over the total number of trips into the city centre in 2041, as well as disagreement over the number of trips by each mode. The original business case has different numbers to the Ministry of Transport review and different numbers again to the Auckland Council/Auckland Transport review. Probably the easiest way to understand the difference in numbers (data from this graph and these graphs) is through a series of graphs, which all compare the current numbers (2010) of people entering the city centre at peak time with 2041 numbers with and without the City Rail Link:What’s somewhat strange about the numbers in the original business case is that the number of people entering the city centre in 2041 with the Rail Link seems to be slightly below the number without the rail link (unless I’m misreading this graph). You would think that the rail link would enable a greater number of people to enter the city centre easily (thereby enabling more jobs in the city centre and all the productivity benefits that brings).

Numbers from the review documents (both MoT and Auckland Transport/Auckland Council) are included below: The numbers between these two reviews are fairly similar in many respects, with just a few key differences. The differences between all the analyses: the original business case (OBC) the MoT review and the AC/AT review are most clearly outlined in the graph below, which compares how each study measured the ‘impact’ of the project (the impact being the difference between the 2041 no CRL and 2041 with CRL scenarios). Now I hope I haven’t completely lost you with the graphs so far, because there are a few more to come – because I think that, if you think logically about the impact of the City Rail Link, all three assessments are wrong and all three of them vastly under-estimate the impact of the project. To analyse why I think this, let’s take a look at a few of the statistics that I question in all three assessments – in particular the level of increase in car and bus traffic to the city centre over the next 30 years.

The graph below compares how each of the assessments measured the increase in car, bus, train and total trips from 2010 to the 2041 with the rail tunnel scenario: While looking at the graphs above, it’s worth keeping in mind the vision for downtown Auckland that the Council has – which was articulated in such glory in the City Centre Master Plan. This plan envisages a city centre with much of its streetscape reallocated to pedestrians – not exactly the kind of city that you would really expect an increase in cars, or a city centre that really lends itself to close to a doubling in the number of bus passengers. So I think that all the assessments (except for the AC/AT one when it comes to cars) have over-estimated the increase in car and bus passengers to the city centre with the CRL built. Many bus routes will obviously change from being long-haul routes to feeder buses, many people who currently drive will be put off by the reduced amount of roadspace as the City Centre Master Plan turns that over to pedestrians, while are also more likely to choose to catch the train as it provides a far better services than before.

If we take the City Centre Master Plan into proper consideration we come to a few obvious conclusions:

  • The number of car trips into the city centre at peak time is likely to reduce over the next 30 years as more roadspace is reallocated to pedestrians. At a broad level, with 34,000 car trips in 2010 a reasonable estimate for 2041 with the CRL might be 30,000.
  • While the number of bus trips is likely to increase to some extent – due to trips from the North Shore and other parts of Auckland (particularly on the isthmus) that aren’t served by the rail network – I think we can assume that many of the current long-haul bus routes from the west, south and southeast will become feeder buses into transport hubs (Onehunga, New Lynn, Panmure and Manukau City seem obvious candidates) with people heading downtown changing onto the rail network to enjoy a faster and more reliable trip. With 23,000 peak time bus trips into the CBD in 2010, I think it’s unlikely that in the 2041 with the CRL scenario we’d have much more than 35,000 bus trips.
  • To calculate the number of rail trips, I’ve kept the “total trips” from the Auckland Transport/Auckland Council assessment the same (that being 104,000). If you take total trips and subtract car trips, bus trips and the generally agreed upon figure of 4,000 ferry trips, you get a total number of 35,000 rail trips into the city centre in 2041 with the City Rail Link.

Adding in my figures to the graph above (and adding in ferries for completeness) results in the following: Before we get on to looking at how my assessment of the ‘impact’ of the CRL compares to the other assessments, we also need to take a look at how realistic the ‘without CRL’ scenarios really are. One thing that’s always frustrated me with with Ministry of Transport review in particular is that they offered no real explanation for how the city centre would cope with all the extra bus and car traffic it would have to deal with by 2041 without the rail tunnel in place. Let alone the fundamental incompatibility of all that extra traffic with achieving any of the goals of the City Centre Master Plan.

The graph below shows the increase in AM peak trips from the various modes from 2010 to the ‘2041 without CRL’ scenario: A few more observations generally on the data:

  • Once again I’m not sure whether the city centre’s roads have the ability to cope with another 7,000 cars arriving in the two hour peak period (the original business case thought this increase would be even higher). The 7,000 extra cars would simply not be possible if we hope to implement anything from the City Centre Master Plan, or if we did implement the plan anyway those cars will shift onto another mode. Overall I’m going to probably say that without the rail tunnel and trying to cope with all the extra buses, we’d probably see the number of cars going down from 34,000 to 30,000 (largely because so much roadspace would have to be set aside for bus lanes).
  • The increase in number of people using the bus is also nigh on impossible for the city centre to cope with – leading to over 500 buses an hour travelling along Albert Street (both directions) and more than 300 inbound buses per hour along Symonds Street. That once again just doesn’t seem possible. More realistically we might see bus travel increase from 23,000 to 38,000 (compared to 43,000 in the MoT and AC/AT reviews).
  • With electrification of the rail network allowing for much longer trains, I think the capacity of the rail network to cope with more peak time travellers will be increased quite significantly from what it was in 2010. Both the MoT and AC/AT reports suggest that we can go from around 5,000 peak time rail arrivals to 11,000. Getting above that level is likely to be physically impossible as your trains are going to be pretty squashed by that stage. So the numbers are probably about right.

What happens when you add up all my numbers (based on the assumptions above) in the “2041 no CRL” scenario is a much lower total number of trips to the city centre: simply because our transport network without the tunnel has a much lower capacity than the transport network with the tunnel. OK now hang in there because we’re almost done. One of the biggest impacts under my assessment of not doing the City Rail Link is the reduced number of total trips to downtown Auckland compared to the other assessments. As the project’s ‘wider economic benefits’ are largely based around increasing employment in the city centre (and taking advantage of agglomeration effects) this is quite a significant difference.

If we put together a comparison of the “2041 no CRL” and “2041 with CRL” scenarios to once again measure the impact of the project, under my assessment we start to really recognise the true benefit of the project – it allows the city centre to grow: If you think about it, it’s quite natural that the impact of a rail project like the City Rail Link would not necessarily be to get cars off the road or to massively reduce the number of bus passengers – because if the project doesn’t go ahead there’s a limit to what the street network can carry and therefore the city centre just simply won’t grow as much as it would with the project. Arguably the lack of a City Rail Link over the past 80 years has significantly contributed to the relatively poor performance of Auckland’s CBD – because it simply wasn’t as accessible as suburban employment areas.

What the City Rail Link ultimately achieves is allowing around 20,000 additional people to get into the city centre at peak times – enabling the city centre to grow without gridlock of buses and cars and also making the City Centre Master Plan a reality.

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  1. > What’s somewhat strange about the numbers in the original business case is that the number of people entering the city centre in 2041 with the Rail Link seems to be slightly below the number without the rail link

    I think the author had misread the graph. I take it to be saying

    Current 2010 rail passengers < 2041 passengers without rail link < 2041 passenger with rail link

    Of course I think we've already blasted past the 2041 projected passengers even without that rail link complete!

    1. The author was meaning the total number of people entering the city, so you’d have to add the columns of each colour. What do you get as the totals for “with rail link” and “without rail link”? My rough addition shows that they’re awfully close. And that’ll be because they’ve kept both land use and the number of “person-trips” the same. This is a fundamental and far reaching error in how transport modelling is done in this country.

      1. Wow, is that true Heidi? That’s pathetically weak analysis if it doesn’t model reactionary influences like those. You’d be better off just making wild estimates from empirical data.

        I guess you can’t argue with “computer says roads”, ay…

        There’s lies, damned lies, statistics… and then computer modelling.

        1. This, John, is why I’m doing what I’m doing. Other types of civil engineers have always joked about our traffic engineering buddies and how they were still ignoring induced traffic. But I always imagined the joke was an urban myth.

          So I read the Waterview Connection modelling report, and realised just how dire the modelling is. Our car-centric planning and road building insanity is propped up by this dodgy analysis.

          Which is why this post is a goodie. The error (keeping person-trips and land use the same) is apparent from the numbers calculated for each scenario, and the post then goes on to show how this skews the calculated benefits markedly.

          It’s why the benefits of probably every public transport project have been underestimated. Usually by a vast amount. And it’s why the post implementation reviews of major road projects are done so rarely – they reflect very badly on the modelling.

          The sector knows they will need other tools to get roading projects over the line, now, in the face of growing understanding about this problem, and in the face of growing understanding about the enormous public, social and environmental costs imposed by driving. The evaluation and business case process is under scrutiny.

          So now the key words are “resiliency” offered by a new road, which is even being applied on roads involving huge cuts that will be ultimately unstable in earthquakes.

        2. You read the Waterview report? I gave evidence on that and they told me there was too much material to email without it breaking the internet. So I went into the lawyers office in town and they had printed out a really large cabinet full of documents. It was full office height and the width of their meeting room. Their instruction was to note what I read and list it but don’t expect to read the whole lot, they didn’t think anybody had.

        3. Sherwood, If you’re interested, there are lots of resources in the references here:

          I particularly like the Litman paper listed there, which has a chart of types of induced traffic and what their relative impacts are.

          This report has some UK post implementation reviews, and reviews of those reviews, and takes a good look at how this misinformed modelling pans out in practice when the roads are built:

          This article puts some context around the misuse of modelling: https://www.researchgate.net/publication/29465763_Clothing_the_Emperor_Transport_modelling_and_decision-making_in_Australian_cities

  2. What I find frustrating is how proposing to build new roads is politically popular despite the negative effects from it. Until that is addressed our transport decisions will continue to be heavily influenced by elections rather than common sense or facts & figures.

    1. “our transport decisions will continue to be heavily influenced by elections”
      Not really. Labour is as pro-roading as National are.

  3. Mason, I wonder whether the huge devastation that is happening to Australia, exacerbated by climate change, will have have any impact on politicians transport decisions that have such an impact on emissions?
    My pick is that the only Australian response will be to buy more water bombers; and our response will be BAU.

    1. Heidi, you are absolutely right in focussing on the analysis that is conducted, because it should be determinative of how money is spent. (I accept, as others have stated above, that mostly matters are decided by low quality political decisions.)

      Someone recently kindly sent me a report on the Draft NZ Rail Plan. How is it that this plan is so devoid of analysis? Let me take just one example:
      “The ATAP package identified investment in Auckland’s rail network (in addition to CRL) over the next decade of approximately $1.4 billion. This comprises rail network upgrades with an estimated combined cost of $940 million, plus $500 million for new trains and stabling.” (So in total we have investment for the full decade of only about twice what is spent on one piece of new road – the Northern motorway extension. Of course we are not comparing like for like because the motorway extension does not include private investment in cars.) As the report points out the rail network, with the exception of the Northern busway is Auckland’s rapid transport network. So why is so little being spent on it? Sure there is the CRL, but that is primarily a project that is mostly of the last decade.

      How did the report authors having said all that they have said about the benefits of rail determine that so little should be spent? Is the gap two light rail projects?

      Surely as the focus on the reduction of emissions becomes paramount, and the price of carbon increases, shouldn’t there be a better examination of the short and long term benefits of all projects?

  4. Hmmmmm yes the modelling sure seems to need to be fixed somehow in NZ particularly.

    Is it similar to the undercooked figures for opening up Britomart I wonder?

  5. I’d like to see AT provide more detailed ridership figures, such as monthly boardings by station and direction of travel. Surely, it would be easy to do so.

    We’re spending $4.4 billion and there should be publicly available data to support their assessment that passenger numbers are nearing capacity at key points in the network.

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