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Monday, April 22, 2024

Is Tunnelled Light Rail the Worst of Both Worlds?

The government will soon make a decision on the light rail (if they have not already done so). If you have read our previous posts on the subject, you will know that we think the elevated light rail is the best option compared to the light rail with tunnels or light metro. This is because not only is it a highly efficient solution, it is also the cheapest of the proposed options, which means we can spread it more easily to other corridors as well, in other words, for the same price, two overhead light rail lines will provide a better result for Auckland than one option with Tunnel.

The Oakland Light Rail (ALR) team has recommended the light rail intermediate route with tunnels, though they also said they think all three options are worthwhile. It certainly has a level of attraction, by tunneling it means we can get a higher level of reliability and frequency, although these will still be very good below the surface option. It also facilitates the use of off-road space on Sandringham Rd for cycle paths and trees without the need for extension.

Moreover, the chair report suggests that it will provide similar results to a cheaper metro solution. Remember, the option of the light rail with the tunnels was about the same as the light metro between Vineyard and Onhonga, but then followed the route across the surface via Manger Bridge and Manger city center.

However, the more I think about it compared to the upscale and light metro options, the more it feels like it’s the worse of both worlds. If the government had opted for an option that includes a large amount of tunnels, it might be better for us to just bite the bullet and go for the full easy metro solution. Here’s why:

The cause without a driver

The main advantage of the light metro over the other options is that it is driverless and will be similar to systems like the Vancouver Elevator or the Copenhagen Metro. Like these systems, it will be able to operate reliably at very high frequencies and do so at a lower cost.

Travel time

Based on the numbers released by the ALR staff, compared to the light rail with tunnels, one stop less and clinging to the freeway corridor instead of the detour through Badr der, means the light metro is five minutes faster between downtown Menger and other stations further north. For Menger residents, they estimate that this means more than 100,000 jobs will be accessible within 45 minutes of travel compared to the light rail option with the tunnels – though I always have skepticism about these model outputs. As a result, the ALR model suggests that it makes the light metro more attractive, and as a result it is likely to have a higher number of passengers.


The focus of the discussion was the capital cost of building these options – just a quick note, all of which focused on the $ 9 billion to $ 16.3 billion headline data, but those costs are inflated by the time of construction and are more realistic. Compared to today’s costs, NPV figures are $ 7.1 billion to $ 11.2 billion – still very expensive.

The focus on capital costs is understandable given their scale, but also because we all tend to want a title number and we tend to ignore the ongoing operating costs. These costs are in an unpublished part of the business case and some things we would expect to be similar between the options, like the cost of maintenance and the power to operate the vehicles. But the ALR team did explain to me that there are actually two other major cost factors that differentiate between the options

  1. Drivers – will be required for both light rail options due to road sections, just as our buses and trains do. For comparison, the easy metro option would be driverless
  2. Tunnels – much more expensive to operate than surface solutions because of the need to operate things like ventilation and safety systems, etc.

That means we get the next matrix.

A light rail tunnel may come out better here during the assessment, but I wonder how it stands on the entire regional network as suggested.

Regional network

The downtown route to the manager is set to be the first step in a new high-speed transportation network for Auckland that complements our existing (and planned) existing train and bus network. It is interesting to note that the planned future network map has been recently and quietly updated to include a second northern coastline parallel to the bus route. This seems like a strange choice, and is probably based on someone deciding that upgrading the bus route would be a hindrance so we need to spend billions to build a parallel route.

In total, the ‘red’ network above will be about 54 km, and it is likely that both the northern and northwestern lines will be completely separated. The only thing that will prevent this entire network from being driverless and the benefits it will bring will be about 6 km of track Around Onehunga and Manga.

Of course regular readers will know that we too are in favor of staged approaches and have even suggested in the past that we could build an overhead light rail line and then a metro-type solution in another corridor in the future. The difference here is that there will always be a need for a quality surface solution on Dominion Rd even if in the end an easy metro is built elsewhere. For comparison, it is unlikely that there will be much use of the overpass just between the Manger Bridge and the Manger city center. So without further significant investment to extend the line it seems it could become a stuck asset.


If we do want to get to Light Metro eventually for the network, there is still no going for the staged approach – vehicle types. This will allow us to go for high-rise metro-style vehicles that have advantages like being easier to maintain, quieter because of the use of boogies and having more interior space for standing.

There is also something appealing about the metro trains that are a bit boxy like these trains from Berlin.

And there’s another cool feature on driverless trains, you can look out the front window.

As mentioned earlier, we still think a top solution is the best outcome for the downtown corridor for the manager and a quality solution will always be needed on Dominion Rd. That does not mean we will not be able to use the light metro in the future in other corridors. However, if the government were to go for an option with a tunnel, a light metro would probably be a better long-term option.

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