Every weekend we dig into the archives. This post by Stu was first published in January 2017.


If you’ve been reading TransportBlog for a while, then you may have noticed that the term “dwell-times” crops up relatively frequently. The term describes the average time that trains are stopped at stations. In several previous posts, we’ve discussed how average dwell-times on Auckland’s new electric trains are approximately 50-60 seconds per stop. In contrast, best-practice dwell-times on rail systems overseas are in the order of 20-30 seconds per stop, so 20 – 40 seconds faster than ours.

In this recent post, I suggested something “had to be done” to shorten dwell-times, to which one commenter (quite reasonably) asked “why“. I was surprised by their question, because to me the benefits of reducing travel-times by 30 seconds per stop seemed obvious. It means that we take Auckland’s trains out of the steam age and into the electric age.

Upon reflection, however, I realised that it wasn’t immediately obvious how apparently small delays of 30 seconds per stop would incur economic costs that warranted action. This realisation motivated me to write this post, in which I attempt to estimate some of the economic benefits of shorter dwell-times on Auckland’s train.

Note that this post does not consider how we might go about reducing dwell-times, and I’d like to ask people who comment not to de-rail the post with such technical matters. The point I’m trying to convey, and which I am interested in discussing, is the economic benefits that flow from running trains faster. Similar arguments apply to efforts to close small intermediate stations, such as Westfield and Te Mahia.

When I think about reducing dwell-times, four obvious sources of economic benefits spring to mind: 1) Reduced costs; 2) Existing user benefits; 3) New User Benefits; and 4) Decongestion benefits. Let’s now dive into the data (hand-waving?) ….

Cost savings: The total cost of running Auckland’s rail services is likely to be in the order of $125 million p.a. Various factors contribute to these costs, but major componenets are likely to be:

  • Staff, including drivers and train managers;
  • Operating costs, such as fuel, mainenance, and track access charges;
  • Asset depreciation, especially on the rolling stock, electrified infrastructure, and depots; and
  • Station operations, such as ticketing and security services.

Different places account for these costs in different ways, which can end up making things quite complex. To simplify things, it’s common to analyse public transport costs in terms of three underlying drivers: 1) vehicle-kilometres; 2) vehicle-hours; and 3) peak fleet requirements. These cost drivers are, more-or-less and to varying degrees, what determine the costs of the services that we operate. Shorter dwell-times won’t, of course, affect the distance that trains travel, even if they will reduce vehicle-hours and/or peak fleet requirements.

To estimate the cost savings from shorter dwell-times, I assumed that measures are taken to reduce dwell-times by 30 seconds per station. If I assume there are 15 stations on the average rail run from Swanson/Papakura/Manukau to the City, then this saves 7.5 minutes on every 55 minute run, or ~14%. I then assume that one-third of this 14% reduction in (in-service) vehicle-hours flows through to the operating cost bottom-line, that is, shorter dwell-times reduce total costs by 4.5%.

Given a total annual spend of $125 million p.a. on operating rail services in Auckland, normal practice dwell-times would reduce costs by $5.68 million p.a. If I then assume an 8% discount rate over 30 years, then this has an NPV of $69.1 million.

That’s the first example of how an apparently small number can lead to a large number when you take a network-wide, long-run perspective …

Existing user benefits: The second effect of shorter dwell-times is to expedite journeys by rail. That us, existing rail users will also benefit from faster travel-times. Current rail patronage is about 18 million journeys p.a., which is predicted to grow to 40 million in a post-CRL world. For the sake of simplicity, let us assume that Auckland averages 30 million rail passengers per year over the next 30 years.

Moreover, I now assume these passengers travel an average of 15km per rail journey. If I assume rail stations are spaced, on average, at one station per 3km, then this implies there are 4 intermediate stations per journey (NB: Remember that users will not benefit from faster dwell-times for the last station). Saving 30 seconds over 4 stations equates to a time saving of 2 minutes per journey. If I assume a value-of-time of $10 per hour, then we can monetize the value of these time savings as follows: (2/60) hours per journey x $10 per hour x 30 million journeys per year = $10 million p.a. This has an NPV of $121.6 million. Happy train users are valuable train users.

New User Benefits: Faster trains will, of course, also attract new users. Let’s assume the elasticty of demand with respect to in-vehicle travel time is -0.50. That is, a doubling in travel-time leads to a 50% decline in patronage. In turn, this means that the 14% reduction in travel-time associated from shorter dwell-times would be associated with a 7.0% increase in patronage, or an additional 2.1 million journeys p.a. If I now apply the rule-of-half, that is 2.1 million x (2/60) x $10 per hour x 0.5 = $0.35 million p.a. Or $4.3 million over 30 years.

Decongestion benefits: Some of the additional rail journeys undertaken as a consequence of faster travel-times would have otherwise been loaded onto the road network. This in turn means congestion would be higher. If I assume that 60% of new rail journeys occur in peak periods, and that 25% of these journeys would have otherwise been placed on the road network, then this suggests faster dwell-times diverts 315,000 vehicles off congested roads every year. If we again assume the average rail journey is 15km long, and that decongestion benefits are valued at $0.40 per kilometre, then I find that decongestion benefits are valued at $1.8 million p.a., or $23.0 million over a thirty year period.


Let’s summarize the estimated economic benefits of faster dwell-times:

  • Cost savings of $69.1 million
  • Existing user benefits of $121.6 million
  • New user benefits of $4.3 million
  • Decongestion benefits of $23.0 million.

Yielding a total of $217.9 million. I must acknowledge these are extremely rough and ready estimates and I could well be wrong and/or out by a decent margin of say +-50%. So don’t anyone go quoting me to the decimal point.

Notwithstanding their approximate nature, the order of magnitude of the estimate is significant. To put it in context, an economic benefit of $217.9 million is equivalent to approximately $7.3 million for every second we cut from average dwell-times. Another way to look at it: I understand the total cost of Auckland’s new trains was in the order of $500 million. Cutting 30 seconds per stop is then worth approximately half of the cost of buying completely new trains. This seems plausible to me; I suspect that a large component of the anticipated benefits of electrification would stem from faster journey times, which have not as yet materialized (NB: In some ways you could argue it’s impressive Auckland has achieved so much patronage growth despite the slow travel-times.

Anyway, the main point is to demonstrate how small time savings can quickly add-up to large dollar values when you take a network-wide, long-run perspective. This is why we harp on about dwell-times and why it’s heartening to see Council putting pressure on AT to sort this mess out. Indeed, cost savings of $69 million above would go straight to Council’s bottom-line, as would approximately $100 million in additional fare revenue over 30 years (NB: This is not an economic benefit per se at it’s simply a transfer from passengers to Council — even if it is of course a fiscal benefit). These fiscal cost savings would result in either lower rates and/or improved services.

In our increasingly resource-constrained world, I consider frugality to be not just prudent, but indeed relatively noble. This is especially true when it comes to other people’s time and money. On this topic, Benjamin Franklin, once said “The way to wealth … depends chiefly on two words, industry and frugality: that is, waste neither time nor money, but make the best use of both.” Confucius put it even more succintly when he said “he who will not economize will have to agonize”.

Or, if you prefer the words of Bruce Lee.

On that note, I suspect my marginal utility of spending more time on this post is by now lower than my next best alternative option.

Have a good ‘un.

Share this


  1. By all means, let’s speed up dwell times, but not at the expense of what happened to me and others yesterday. I took the train down to Takanini on business. On the return journey, I got off at Puhinui, intending to transfer to an Eastern Line train that would double back a little way until it branched off to Manukau where I intended to have lunch.

    On alighting at Puhinui, an Eastern Line train was already stationary with its doors open. A middle aged woman and I made a fast crossing of the platform, only to see the doors close in our faces. The train stood there for about 10 seconds and then departed. We had missed it by about two seconds.

    It gets even more interesting. The woman and I had to wait 20 mins for the next Manukau service. When it arrived we boarded, and unbelievably the same thing happened. A northbound train arrived simultaneously and despite the best efforts of a young man to sprint across the platform, the door literally closed in his face.

    Wouldn’t you think that when two trains meet simultaneously that there would be a small wait for transferring passengers? Or do drivers assume that nobody travelling northbound would want to double back southbound? If the latter, this displays a total lack of awareness of the track network and the transfer system at places like Puhinui and Otahuhu for those going to Manukau.

    1. Same often happens at GI, and yes, there is no “waiting” for passengers from the two trains to sync up.

      Mind you few people would get off a train that just stopped at GI, to then hop on the train going the other way, unless they missed their stop. Pretty small number.

      But it is a valid point for Puhinui where it is a transfer station to get to/from Manukau from the south.

      “Major” stops like GI have a policy of [supposedly] never departing before the allotted time, no matter how early they arrive.

      But I often noticed the trains at GI that arrive early open the doors as normal, then close the doors, and will sit then there for a minute or 2 with the doors firmly shut waiting for the clock to reach the alloted departure time, to then go. Why bother closing the doors that early why not leave them open until 15 seconds prior to departure or whatever the minimum period allowed is?

      1. Yes. Penrose is another spot. You should be able to connect from the southern line to the Onehunga line and vice versa.

        1. No, Penrose is different. Yes, passengers transfer from one line to another there, but there’s a very long walk between platforms via the overhead walkways. Drivers can hardly be expected to wait 3 minutes for walkers if they see a train at the other platform.

        2. True, but coordination of the timetables would be useful. I suppose there wouldn’t be many people making the connection, but when I’ve been there I’ve noticed that if people did want to, the timing was just wrong.

        3. The connection is much easier at Ellerslie, and most of the time the extra 2 mins each way just replaces time you’d spend waiting at the platform.

        4. Can’t work both directions though really with 2 trains per hour Onehunga line. Do you make it time for Onehunga to south or going north on the Southern line to then go out Onehunga way. Can only make the southern 10mins all day then it should work.

      2. I have had the opposite as 4mth’s ago I got a bus from Gray St in Mangere to Otahuhu to get the train from there to britomart and as I and 4 others got to the train the doors closed and thinking I and the other had missed it the doors then opened again for us , so we were able to continue our journey and I think the TM was in the right position on the 6 car train to see us. we then thanked him and he told us he does it all the time if he sees passengers trying to board only if they are running or moving fast as the doors close

  2. I propose a new, additional definition of “dwell time” as follows:

    The interval between discussions on GA and elsewhere about speeding up Auckland trains through proposals to reduce station level “dwell time” (the time an individual train spends stopped at each station on its route).

    I’ve lost count of the number of “dwell time” discussions that have been had at GA and also ATB over the last 5+ years.

    The simple fact is, that despite all the time, the discussions here, beneficial economic analysis up the wazoo and a few lacklustre attempts by AT to get consultants in to “do something”, the result is that the journey time from Panmure station to Britomart isn’t really any better/faster than it ever was in the steam powered days.

    So we have a long way to go to literally leave the steam age behind us. Something which the electric EMUs with their much better acceleration/deceleration should be able to achieve with one set of traction motors tied behind their proverbial backs.

    And it is now over 4 years since the EMUs were first put in service and nearly 5 years since they first arrived and started acceptance testing on the Auckland rail network. I think thats more than enough time to realise there is a big problem, that we need to fix it, and to actually put in place, a full set of measures in place to fix it.

    And yet, here were are, still talking about something that most other modern commuter rail systems worldwide have managed to solve fairly easily.

    You have to ask what’s so special about [the management of, and running of] the Auckland train network that makes it simply unable to also achieve the same?

    1. How refreshing to see someone finally spit the dummy and state the oh-so obvious that improving train dwell times is just completely impossible under the current management

      1. You also must remember that all the train times are controlled by KR and train control in Wellington if they transferred train to Auckland as a local system and then just use Wellington for the rest of the country then everything may then be speeded up . AT has to supply the timetables to KR and then get them approved . Signals are all controlled through wellington and there must be a time delay from the time they push a button till the time the signals change

        1. KR will not alter AT’s proposed timetables without a compelling reason and only then after extensive discussion and negotiation. The approval process that KR requires is mainly to ensure that its freight services are not compromised over the shared system.
          The timetabled run times and dwell times are set by AT, and it is they who are working on speeding things up. KR’s train control does its best to operate the network optimally for the service that AT has specified.

          And a signal controlled from Wellington will operate just as quickly as one controlled from Auckland. The propagation-time for an electrical or fibre-optical impulse from Wellington to Auckland is about 2 milliseconds!
          This is not the reason for slow trains!

  3. Greg N, point well made.

    I will say it again that the dwell times on Sydney’s double decker trains are less than AT trains.

    AT can do it, they just have to want to do it. I travel the Eastern line relatively frequently and last year the standard dwell time was about 55 secs with the quickest I measured at 40 secs. The levels of patronage seemed comparable. I no longer measure the times as there seems little point in becoming frustrated every single time you travel. I do have the impression that AT have shaved a minute off the Brotomart – Manukau journey time.

    1. Just arrived in London today and took the District Line tube to my accommodation. Timed the length of the average “door open” time at just eight seconds. Hmmm . . .

      Mind you, that seems excessive compared with the Moscow Metro!

      1. Dwell-time is the time from wheels-stop to wheels-start. It is more than just the doors-open time. I have repeatedly clocked dwells on the London Underground as taking around 30 sec at busy times. Still way shorter than Auckland’s.

        In Wellington dwells can be as low as 15s during non-busy times.

  4. It is not just dwell times. Our trains accelerate and decelerate much slower than some overseas. They are already capable of better performance but are being restricted probably by somebodies idea of safety but I believe excessively, given overseas experiance. Again there are several seconds to be saved with each stop or bend.

    1. one of the unintended consequences of health and safety (which is probably well intentioned) where trying to make a very safe mode even safer is the added cost resulting in a modal shift to less safe modes. Rail in NZ is full of examples of this.

      1. Agree. It is because the different transport modes operate in silos. It doesn’t seem to matter if your safety policies drive (or force) customers to use more dangerous modes, as long as your ‘silo’ is operating safely. The classic example of this is where some small safety-issue on the railway prompts the operator to mandate bus-replacement, but with no consideration of the comparative risks of bus-travel!

        And of course the other problem is the vastly different safety regime on the roads as compared to any other field of transport or industry.
        I long for the day when an equivalent zeal for safety gets applied to road transport. Nothing would be allowed to move!

  5. So true this post. Sure hope they can more radically speed things up & make things more frequent off & inter-peak in this change planned in Feb 2019.

Leave a Reply

Your email address will not be published. Required fields are marked *