The other day I covered part of the case against having an Eastern link, with this post I thought I would look at the case for building it and also whether we could live with things if it was not possible to grade separate the junction with the western link. The three key reasons in the case against building the link could be called the three C’s:

  • The Catchment – Aotea is about the same distance from Newmarket whether you go via Grafton or Britomart however there is forecast to be a bigger catchment around Britomart so it pays to serve the majority of people first.
  • The Cost – My understanding is that due to the geography that grade separation is going to be tricky and therefore very expensive.
  • The Cross – Future patterns discussed on this blog and hinted in a few planning documents suggest that we may eventually look to a cross type pattern when we eventually build a rail line to the North Shore, if that happened we wouldn’t need an eastern link so why spend money on it now.

The Eastern Link

First to counter these issues:

The Catchment

Of the CRL stations and Briomart approx 50% are forecast to go to Aotea with 30% going to Britomart and the remaining 20% going to both K Rd and Symonds St. With an Eastern link a direct journey to Grafton from the south opens up and I suspect that would help to balance these numbers out a bit as there might be just as many, if not more students that would benefit along with people visiting the hospital and local workers.

The Cost

The eastern link won’t come cheap, especially if it is grade separated however I think I may have come up with a way to reduce the cost but more on that soon.

The Cross

I really love the idea of the cross as it is really simple and also allows us to have a ton of capacity through the core of the network. Many people have commented that they are concerned that it is hard enough to build one CRL and that a second one would be almost impossible. Based on the current political climate that is definitely the case however I suspect that the CRL will be far more popular than it is envisioned and that will help in the case for future development. Regardless any other CRL style tunnel will not likely to even be started for another 15-20 years and so the question becomes, do we not build something now because we may do another project in 20 years time?  My feeling is that 20 years is a long time for a project still pretty firmly in the maybe column at the moment. How we build the link may also have implications for when that other tunnel is needed but again more on that soon.

There are other things to consider as well however. As Nick will repeatedly tell us the service pattern is essential and without the eastern link you are left with either an unbalanced network with really high frequencies out west or you need to terminate some services just after the CRL and send them back down largely empty. That is where our previously suggested operating pattern comes in:

As mentioned earlier, assuming that the cost to grade separate the eastern link is too high, I think I may have a suggestion for reducing the price of the link however it does come at the cost of services. The key thing would be to build the link as an at grade junction but before you all jump up and down hear me out. Most people know that an at grade junction, either on road or rail, limits the capacity of the network. On a rail network like ours, the number of at grade junctions can often mean that one late running service causes ripples throughout the rest of the network. We do know however that the junction at Quay Park (outside Britomart) and at Westfield have the ability to handle about 20 trains per hour in each direction (TPH). By comparison the most suggested that we could get with the CRL was 30 TPH although with through routing of serives it represents a much larger capacity increase. From what I have heard,  a more realistic number for us to achieve would have been 24-26. We obviously want to avoid the issues of delays grinding the rest of the network to a halt so as part of this we would however need to grade separate the other junctions of which Newmarket would probably be the hardest.

With that done we should then be able to easily run 20 TPH through the CRL without the delays spreading to the other junctions and our services could be designed to reflect this. The pattern above could then have 10 TPH on each line which would represent a train every 6 minutes and a peak frequency up or down the CRL of a train in each direction every 3 minutes. Of course this means that at about the same time as it will take for us to need a new harbour crossing we will likely also be looking to take some pressure of the CRL and that is where the line from Parnell to the North Shore comes in.  In effect this this would be taking a leaf out of the motorway builders book where by they build a section then and leave it for few years while pressure builds up from the public who demand money be spent on finishing the job.

But what happens to the link after “The Cross” is completed. My thoughts are that the link will still be useful for a number of possible reasons. First it allows trains from the east to also use the spare northern link at Newmarket to get back stabling yards either at the strand or down at the EMU depot in Wiri. Another option might be investigate using the tunnels as a linear stabling yard to help save on operational costs or perhaps we just keep them for use in emergencies. I guess though that the key thing is it gives us options and at the very least we should include it it in the designation phase.

I think at the end of the day there are some good arguments for either building it or not. I haven’t actually decided what my preferred option is but think it is good for us to discuss them.

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  1. I would add two more ‘C’s to the comparison, Convenience and Capacity.

    Without the eastern link the network is very unbalanced, with one line on the west side of the CRL and three on the east side. So that means two lines can run through but the other two will have to terminate in the CBD. That’s not very convenient if you’re headed to or from somewhere that isn’t the CBD, it’s also very inconvenient if you’re going the other way to the main flow of travel (say from Grafton to Onehunga) or if you are trying to get around within the CBD (say Newton to Newmarket).

    The other thing is capacity. If the CRL has a max capacity of 20 trains an hour each way that is the maximum for the system. With an eastern link we can run all four lines through and divide that capacity evenly, as Matt noted above we get 10 trains an hour per line in service.
    Without the eastern link we need to assign some of that capacity for half the lines to pass back through the tunnel again after they’ve terminated and turned around. So dividing the capacity evenly across four lines in this configuration means we only get 6.66 trains per hour per line.
    In other words not building the eastern link means only two/thirds the capacity of the tunnel with a flat eastern link. We’d be limited to little better than a train every ten minutes on four lines.

  2. The other big question is “what do you need to build instead?” You’re going to need a pretty serious piece of infrastructure to turn trains around. Building that in Mt Eden / Kingsland will be expensive and potentially very unpopular.

  3. Trying to picture what that alternative piece of infrastructure could be. If all the western line trains connected with the southern line trains, then eastern and Onehunga trains would have to terminate somewhere along the western line and head back through the CRL.

    Perhaps a couple more platforms at Kingsland station would be sufficient for this. It would require purchase of residential properties on Sandringham Rd or commercial property on new North Road or both. I wonder if this would be substantially cheaper than building the CRL eastern link?

    The big benefits are:
    1. No need for CRL eastern link.
    2. Massive rail capacity at Eden Park and the ability to move people from the area very quickly.
    3. Potential for some serious TOD redevelopment at Kingsland (and Mt Eden Stn) due to the very high frequency of trains to the CBD.

    1. Yes there is the saving, but as Peter says what would we have to build instead? Some means to run through say ten or twelve trains an hour each way, but also turn around ten or twelve without fouling it all up. Don’t think you’ll get that in the footprint of Kingsland station, and just thinking about it you’d need some pretty fancy track work anyway. I do wonder if there would be any real difference in price between the options.

      No sure if your last two points are really a concern, with the CRL Kingsland will get a huge boost in frequency plus improved travel time anyway, so increased development is likely regardless. Likewise with Eden Park they can run a heap of service with or without a terminal station there.

      1. I think there is space at Morningside station for trains to switch ends. Was used at Rugby World cup, although would have to add a few extra crossovers at either end. Not sure we would have 12 trains per hour each way for another decade or so after opening anyway. Trains would terminate at Kingsland though and use Morningside to crossover.
        If we go with driverless metro for the North Shore line we need the long term flexibility for the heavy rail network anyway, am not in favour of replacing existing heavy rail infrastructure to change to driverless. So therefore it should be built.
        However if we go for a half arse staged version I think we will be able to cope without it for a few years, as long as the Newton junction is designed to be staged. Then it should be built once frequencies start to head higher.

  4. Matt, your first map is a little odd, you’re not suggesting removing the current track towards Grafton surely?

    An at grade 3-way link won’t limit network capacity anymore than the other tight points on the network will it; Newmarket and Britomart? In which case it will serve us for a good few years yet. Looking at the junction north of Newmarket an at grade junction doesn’t even take up much space, so I can’t see it saving much by leaving it out…

    1. The existing line would definitely still be there but passenger trains wouldn’t use it as per this post.

      The problem with so many flat junctions is that one little delay can affect the whole network e.g. a train gets delayed due heavy loading and as such misses ‘its slot’ on the junction. That then delays a train on the other side of the junction etc. That is why I suggested that if we built an at grade junction on the CRL we need to grade separate the other ones on the network to prevent this from happening (or at least from it being so bad).

  5. Build the eastern link as part of the CRL project. As Nick R says, without it, the whole system will be unbalanced. It makes far better sense to have both eastern and western links….and anyway, its likely that even with both links built and just Aotea and Newton stations put in, the cost will be under NZ$1.8 billion anyay, so why penny-pinch? Way lower cost than some of these motorway projects the government is pouring money into and far better value for money.

  6. I am missing something or does there actually even need to be much of a junction. Surely if you have Western trains turning left into the CRL at Mt Eden and then Onehunga trains turning right just after Grafton into the CRL. So there would be only be problems with an at grade junction if you ran any Western trains straight ahead towards Grafton / Newmarket.

    Clearly having some two platform terminus at Kingsland would be ridiculous.If I recall correctly there are no cross overs at New Lynn currently.
    Without an Eastern link we would either need to (and probably both):
    (a) Build the full or some of the ASL to divert some of the traffic instead of running all the way to Henderson or Swanson.
    (b) Create a four platform terminus station somewhere in between Mt Eden and New Lynn.

    Also doing the “cross” is only one possible running pattern. There are alternative ways that could use the Eastern link.

    1. Well it would be the same sort of junction we have currently at Quay Park, two lines merging into one going into the tunnel, and one splitting into two coming out. The biggest issue is that the outbound to one leg would conflict with the inbound to the other. But yeah it’s not nearly as bad as a full three way junction would be.

  7. That proposed operating pattern has 5 conflicting moves, or 6 if there is a flat junction at the end of the CRL.

    Why such a focus on a single conflict when there are so many other conflicts in the system?

  8. Quick question, what about lengthening the tunnel to achieve grade separation? This could be done with a spiral tunnel or a dogleg of some sort?

    1. My plan above shows how it could be done. Two of the four CRL tracks would be the currently planned tunnels and two on lower levels would extend a bit further out to emerge either side of Mt Eden.

  9. Personally , due to my interest in transport to Auckland hospital and Auckland medical site rough guess 5,000 people per day and spent about $20 million on new carparks in last 2 years, I would be keen to see the Eastern link. I would like to see Trains from South (Including Onehunga) go Newmarket- Grafton then where ever (probably loop thru CBD as more wanting to go to city than West). If there is no Eastern link I fear trains will all go Newmarket -Britomart and therefore a poor service for people from South getting to Auckland hospital and Medical school. This will lead to more millions being spent on carparks rather than on healthcare.

  10. Build the Eastern link.

    Not building the Eastern Link essentially means (as pointed out by others):
    1. Developing an expensive turnaround station somewhere else; and
    2. Reducing the legibility and operational flexibility of the network; and
    3. Lowering the effective capacity of the CRL by running empty trains through it.

    We need the CRL urgently because Britomart was under-designed; but we are now proposing to do it again with the CRL? That’s the definition of insanity …

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