Over the coming decades Auckland’s budding rapid transit network is expected to grow significantly, approximately tripling in size from what it is today. While a decent proportion of will be new and extended busways, new rail lines will also be built, in particular a new light rail network serving the North Shore, the Northwest, the Isthmus and Mangere. These are the blue lines in the map below.
Recently we’ve seen an increase in comments here and in other places suggesting that these future rail lines should be designed to the same standard as our existing rail network. With this post I wanted to look at some of the common reasons given for this and why it’s a good idea to keep them separate.
Note/warning: This post isn’t another light/heavy rail mode debate and the arguments are intended to be equally valid if we were to decide to build the blue lines as some form of heavy rail. If the comments descend to become another mode debate with people talking past each other, I am liable to ban some commenters without warning.
City Rail Link doesn’t have the capacity
The CRL represents a significant upgrade to our existing rail network and it’s not often a single project can more than double the capacity of an entire network. It was also a long and contentious path to get to the point we’re currently at with the project under construction that we don’t want to have to repeat again anytime soon. Some have questioned why we can’t make use of all that extra capacity.
But we can’t take all that new capacity for granted and if there’s anything we’ve learnt over the last decade or so is that Auckland’s rail network usually grows stronger than expected. As such, the most recent analysis suggested the CRL could be at capacity within a decade of opening and future proofing is now being included to allow for up to 9-car trains to operate. This same strong growth is also why the work to support greenfield growth is considering whether we need a second rapid transit route in the south. This means that services for any new lines, if they used the CRL, would have to come at the cost of services on other lines.
In short, even it was technically feasible to add another line into the CRL, we’re going to need all the capacity we can get from the CRL just to support the existing rail lines. Any new lines would be better to interchange with but not use the CRL.
It’s not feasible to build a connection to CRL anyway
Even if we wanted to sacrifice some capacity on those other lines, there’s also the question of just how we’d do it. The only plan we’ve seen was from way back in 2003 where a junction was suggested under the downtown site but to build that now would likely require the removal of the still under construction 39 storey Commercial Bay tower. Even if you could go to this expense, why would you? People wanting to travel to other parts of the city centre, say Karanagahape would still have to transfer anyway.
It doesn’t get any easier to connect anywhere else either. One of the challenges with the CRL is that between the stations the tracks needs to rise at or close to the limit for a rail system of this kind. Overall it rises about 70m over the 3.2km of the tunnel and that means even if we wanted to, there’s not the ability to add another junction in.
What has happened however, is the CRL is being future proofed for a perpendicular line under Wellesley St. You can see this in some of the technical information CRLL have posted about the Aotea Station. The image below is for the Southern end of the station at Wellesley St and you can see the grey lines separating to make space for a potential platform. This would obviously be very disruptive to build but could be used for any mode.
We’ll save any conversation for if we should use this route to another post.
A connected network is a better outcome
Overseas it’s not uncommon to see metro lines that have branches, often near the ends of the network, but one thing you don’t see is networks where all lines run services to all other lines. By having interchanges between lines it allows networks to run each route with higher frequencies making them faster and more convenient for more people. This is the same principle behind the new bus network that was rolled out over the last few years.
What this means is that providing good connections can be provided between this new second rail network and the existing one, whether it be under Wellesley or on the surface, it will mean that people can easily transfer between services to continue their journey.
A connected network delivers another important feature that can’t be achieved with trying to share the network, it provides more resilience.
Auckland’s network has improved significantly from the days when we used to see multiple signal or track faults on a daily basis. However, we still occasionally have issues, whether it be a train/network fault or an incident at a level crossing – the most disruptive being the derailment in Britomart last year. Given Auckland’s already tight network with lots of junctions, a single issue on one part of the network can quickly cascade and impact on services on all parts of it. If we were to build new lines, why would we not want it independent of the existing network? The last thing we want is a single failure taking out the backbone of our entire PT network.
We’ll need a new depot anyway
One suggestion I hear from time to time is that by keeping our trains the same, we can make use of the existing EMU depot. At the time of it’s construction, AT said the depot was future proofed to be able to handle up to 109 trains, just under double the 57 we currently have (with 15 more under construction). With the City Rail Link increasing frequencies and potentially 9-car trains in the future, that likely won’t be enough just for the trains needed on our existing network and so we’re likely to need a new or expanded depot anyway.
This also means we certainly won’t have capacity in the existing depot to also handle trains serving the ‘second’ rail network.
The technology not being the same is fine, maybe even ideal
There’s no reason why we have to have the same style trains designed to work on a network first built over a hundred years ago. In fact many cities have a lot of different types of rail technology and designs and that isn’t an issue because they don’t have to inter-operate due to the network design principles mentioned above. Often when new lines are built they are built using the technology of the day. A few examples are below but almost all cities tend to have a mix of technologies depending on when the various lines were built.
- London – Crossrail is being built to very different specifications to the other parts of the underground network, which itself has different specifications depending on when the line was built.
- Sydney – the existing double decker trains are too big to fit on the new metro line under construction, which see fully automated single-decker trains operating.
By building a new network we can ensure that we build it to the latest standards without the baggage the current network has, such as trains that have completely level floors for easier access.
It shouldn’t be designed to accommodate freight
It’s important that this new rail network be focused on providing high quality public transport at all times of the day. That includes the ability to run services at high frequencies. Having to accommodate freight only serves to dilute this ability and on our existing network remains a significant obstacle to running trains more frequently outside of the peak. Not to mention would also be a bit bizarre to be standing on an underground platform, say at Aotea, and suddenly see a freight train roll past. Is there any metro where that happens?
All up I don’t see any value in the suggestion that any new rail lines have to be the same or be interoperable with our existing network and if anything, is only likely to make building these lines more difficult and costly.