Perhaps more than any other post on this blog, the one which really got me fascinated by Auckland’s transport future and convinced me I “wanted in” was a post by Nick R about how driverless trains – the kind used by Vancouver’s Skytrain system that I’m so fond of – could have a role in making rail to the North Shore far more affordable and feasible than perhaps we have ever thought before. There are some key elements to what Nick calls “driverless light-metro”, which make it such an incredibly appealing transit technology:
- The driverless operation means that the connection between frequent and operating cost is broken (you don’t need to add a driver for every train you add). This allow off-peak service frequencies to remain high, shorter but more frequent trains to be run and operating costs of the system to be kept pretty low. Vancouver’s Skytrain system, I have heard, makes an operating profit.
- The linear induction motors, the lighter vehicle weights and the technical details of these trains allow for sharper bends and steeper gradients than would ever be possible with conventional heavy rail. Nick’s posts on the technology suggest that 1 in 10 gradients are OK (the CRL is really pushing the envelope at around 1 in 28), while 35 metre radius bends are also possible – yet again much sharper than for conventional heavy rail. A more forgiving geometric requirement means much much cheaper construction cost.
Essentially, a driverless Metro is far cheaper to build and far cheaper to operate than conventional heavy rail. It almost sounds too good to be true – so what’s the catch?
Well effectively there are two main catches. Firstly, because the trains are driverless they need to be operating on a system which is completely grade separated and completely protected from pedestrian intrusion on the tracks. Secondly, the highly specialised traction technology and the less forgiving gradients mean that light-metro tracks are pretty much passenger service only (no freight) and also limited to the particular type of train you run on them – so no inter-city passenger trains or future EMUs running on these tracks. Just the driverless light-metro trains.
These restrictions create an interesting conundrum. While there’s a highly compelling case for all new rail infrastructure to be in the form of a driverless metro, for the far cheaper construction and operating costs, because we have an existing heavy rail network, which we run freight trains along and which we are also investing heavily in maintaining/upgrading as conventional heavy rail, we’re left in a tricky situation of wondering whether, and how, this fantastic technology could be used in Auckland.
Nick’s suggestion was that the North Shore Line be constructed as a Light Metro, operating pretty much independently of the existing network, with possible future extensions along SH16 and SH18 to form some sort of northwest rail loop. The case for rail on the North Shore being constructed in the form of a light-metro is, I think, compelling. Firstly the harbour crossing itself is going to be far far cheaper than for conventional heavy rail (Nick has pointed out that it could sit underneath a road tunnel or potentially even under the existing harbour bridge as unlike conventional heavy rail it would be able to handle the gradient). Secondly, one would imagine that it would be much easier to turn the Northern Busway into a light-metro line than into a conventional heavy rail line – once again because of the more forgiving geometry of the light-metro technology. With a study recently estimating that a whole heavy rail line from town to Albany up the busway being approximately $2.5 billion in cost, a light-metro line may well be significantly less than this (very significantly less if you can sling it under the existing bridge).
What has thrown a few “spanners in the works” of this plan over the past couple of months has been the general thinking of us bloggers around future operating patterns for trains once the City Rail Link is completed. In particular, the general agreement that linking up the western line and the eastern line via the CRL and the North Shore with the southern line via another tunnel, would create the most logical and best long-term operating pattern for trains passing through downtown Auckland. That creates an outcome something like this, as nicely illustrated by Patrick’s post on the matter: This operating pattern has some hugely attractive attributes:
- By effectively creating four independent lines into the city centre (both directions on both lines) you have a simply huge amount of passenger capacity. If you ran 24 trains per hour each way along both lines, for example, you’d have nearly 100 trains per hour bringing people into central Auckland – around 75,000 people per hour with 750 passengers on each train.
- You create a really logical route structure for Auckland’s whole network (setting aside the question of how we deal with Grafton station). There’s a basic north-south line (the blue one) and a basic east-west line (the red one). They cross over in the very heart of Auckland’s city centre.
- We do away with the incredibly slow bend around Vector arena (though I’m sure you’d keep the tracks there, at least you wouldn’t need to use them for regular service).
Of course, by linking up the Southern Line with the North Shore Line, we’ve just created ourselves one heck of a headache when it comes to our idea of that North Shore line being a driverless light-metro. Or have we actually opened up an opportunity here?
What if we tried to make that “blue line” above fully driverless Light Metro? Let’s explore that idea.
If we remember back to the start of this post, the two big restrictions for driverless Light Metro is that it can’t share track with freight trains and it can’t share track with any other kind of passenger train. Effectively, it has to be its own independent network. That does create use a few headaches. But potentially they’re not impossible to solve. Let’s just say we built the line in blue below as a light-metro line: Yes, yes I know there are issues, but first let’s look at the positives. We probably have a cheaper construction cost for the Airport Line due to the easier geometry of Light Metro. We also have much lower operating costs. There’s a direct line between the North Shore and the airport, which would probably generate quite a lot of patronage and would certainly ease traffic on what’s a pretty big “through movement” at the moment (Waterview Connection eases this pressure on arterial roads but not on spaghetti junction except for people up around Albany who may use SH18/SH16).
The main issue, obviously, is that we have existing sections of track along this alignment – from Parnell right through to Onehunga and Otahuhu. However, if you add in the conventional rail network which would provide the main “south/east-west” connections, there actually isn’t much overlap between the lines at all – just between Westfield and Otahuhu by my calculations: The other key consideration is, obviously, rail freight. But from what I know the Newmarket-Westfield section of the southern line isn’t really used much by freight trains (they prefer the easier gradients of the eastern line), so the only section which would require side by side conventional and light-metro tracks would be between Parnell and Newmarket, unless some other solution can be found to send freight out west via the Avondale-Southdown line (including the Onehunga to Southdown link which isn’t shown above).
I actually kind of think all of this could work, with Auckland ending up with two completely independent rail networks. While that has some disadvantages in terms of route flexibility and the need for transfers for trips from south of Otahuhu to Newmarket (for example), I think the cost savings (both capital and operating) which would arise from being able to build both the North Shore Line and the Airport Line (at least the northern link, the eastern one is something that probably required a bit more thought) as Light Metro lines would probably run into the many billions of dollars.
Which means it’s something worth looking into. Driverless light-metro indeed could play a very important role in Auckland’s rail future.