The CBD Rail Tunnel project has been proposed for around 80 years now, and has popped up at various point during that time: in the 1920s, the 1950s, the 1970s and most recently since 2004. This latest occasion will hopefully be the “real thing”, and we will finally get this critical project constructed after 80 years. Given that the current study into this project will clearly build upon previous work, I think it’s a good idea to have a look at what we already do know about possible alignments, grade issues and station locations. Which is why it was pretty handy to get my hands on the full copy of the 2004 URS Report into the CBD Rail Tunnel this week (warning, it’s about a 10mb PDF file!)
There are a number of interesting aspects to this report, most notably the different options that were looked at regarding preferred alignments, the different possible station locations, the consequences of different grades for the tunnel, and perhaps most interestingly – a relatively detailed look into both the business case for the project and a look at how much it might cost.
Firstly, if we have a look at the different alignments that were considered we can see a whole range of options were looked at, but eventually it became fairly obvious that the route that was eventually chosen was the obvious preferred option. The map below shows the different alignments that were considered: These different options are described below:
Option 1: Albert Street ridge line/Pitt Street/Mercury Lane/under the Southern Motorway/Upper Queen Street/Newton Rd under New North Road to the Western Rail Line;
Option 2A: As per Option 1, except for improving the operation of the alignment by removing curves
near Karangahape Road and Upper Queen Street. The gradient is 3.0%;
Option 2B: As per Option 1, except for improving the operation of the alignment by removing curves
near Karangahape Road and Upper Queen Street. The gradient is 3.5%;
Option 3A: Albert Street ridge line/Pitt Street/Mercury Lane/under the Southern Motorway/Ian
Option 3B: Albert Street ridge line/Pitt St/under the Southern Motorway/Ian McKinnon Drive;
Option 4: Albert Street ridge line/Aotea Square/Myers Park/Queen Street/Upper Queen
Street/Newton/New North Road to the Western Rail Line;
Option 5: Nelson Street/Wellesley Street/Symonds Street/New North Road.
When the different options were analysed, option 1 was discarded because its alignment resulted in too many sharp horizontal curves which slowed down services and reduced efficiency; options 2A and 2B were carried forward as the preferred alignment (I think 2A is better so that the tunnel’s grade is minimised); options 3A and 3B were discarded as it was found to not be technically feasible to operate trains along the grades necessary to clear the messy New North Road/Ian McKinnon drive interchange; option 4 was discarded once again because its grade was too steep (and it would also get very close to the underground Aotea carpark) while option 5 was considered not feasible because its stations would be a long long way underground plus the extra length of the route would add significant cost to the project.
I agree with the conclusions made in this report, that option 2 (preferably 2A) is the best alignment. I had wondered about something along the lines of options 3A and 3B, as that seems to mirror the original alignment of the ‘Morningside Deviation’, as this project used to be known. However, I can see how the location of the New North Road/Ian McKinnon Drive interchange would make that option difficult if not impossible.
As I have explained previously, the gradient of the tunnel does still push the limits of what is feasible (a large part of the reason why I support option 2A rather than 2B). The image below shows a cross-section of the two options – with the green line showing the alignment of the tunnel and the red line showing a cross-section of ground level. Of most interest is to see (it’s a bit small on the image below sorry so you’ll have to download the PDF or trust me on it) that at the K Road station the track is about 28-31m below ground level, that the tunnel will pass about 20m below state highway one just to the south of K Road, that that Mt Eden station itself will be about 20m below ground level and that the Midtown station will also be about 18m below Albert Street.
The alignment of the tracks at both portals is also quite interesting. At Britomart the tunnel will link into the current system through an extension of the tracks that serve platforms 1 and 5. These will continue underneath QEII square (what’s left of it) and the downtown shopping centre before turning a sharp left and heading underneath Albert Street. There has been some thought into how this could integrate with a future North Shore Rail Link, although to “grade separate” those two lines (which is probably necessary) there would be significant extra cost. The aerial photo below shows the possible alignment of the tracks around this northern end of the tunnel: At the Mt Eden end of the tunnel the difference between options 2A and 2B becomes more obvious. As 2A has a lower grade within the tunnel, it will emerge much lower than option 2B. Therefore its tunnel/trench is far longer, and the western line also needs to be lowered throughout this area into a tunnel. This is further detailed in the diagram below: Looking at the above image, I actually think that option 2A would be preferable in another sense, and that is ensuring that we don’t end up with a giant wasteland created by the rail triangle that the yellow portal area (option 2B) would create. This whole area will need to be acquired for the construction of the link, but if it can be capped and then redeveloped there is the opportunity to really revitalise this part of the city – and for KiwiRail/Ontrack to hopefully make back quite a bit of money through redeveloping it.
I talked about the preferred station locations in detail in my previous post on this project, and these are basically identical to what has been proposed in the URS report, which I include below: Now of course, the big questions come down to “what will it cost” and “it is justified”? This is where things get a bit messy in the URS report, as it proposes a cost of around $500 million for this project – whereas subsequent analyses have put a more likely cost at around $1.5 billion: three times as much. Now I have wondered “how could they have under-estimated so much?”, although having a look through the analysis that was done to work out the costs it seems as though URS were fairly robust in their work. The breakdown of this cost is outlined below:
In terms of “is it worth it?”, obviously at some stage a full cost-benefit analysis of the project will need to be undertaken, and the URS report really only makes a tentative beginning at that. I have always considered that the biggest benefits of the CBD Rail Tunnel might be quite difficult to measure, with things like effects on development within the CBD, the fact that it makes possible other extensions to the rail network, and the mess that will happen at Britomart if this does not happen, all being potentially difficult matters to properly “measure” when working out a full cost-benefit analysis. The URS report highlights these difficulties:
This is a complex project due to uncertainty as to how the network will change and evolve and the timing of those changes particularly if the tunnel is constructed – patronage and train operating pattern are unclear at this stage. For instance, if the tunnel and stations are completed before the need or decision to electrify and double track Mt Eden to Newmarket, and to enhance the station and the approach to Newmarket Station then considerable savings can be made. If the tunnel is completed after these investments then they are sunk costs and no savings can be made.
The most significant benefit is the opportunity for Auckland City to re-establish the CBD as a place for work, entertainment, recreation, health services and education. It is almost impossible to value this aspect. Patronage is difficult to forecast. Currently, only 12% of the Region’s work force works in the CBD. Only 35% of the people coming over the harbour bridge go to the CBD, the rest go elsewhere. More people cycled to work in the CBD than used the train in 2001.
Readers should note that this is an economic not a financial analysis – some of the benefits are intangible: such as the benefits of less pollution and increased reliability of travel time. Other benefits do not result in any cash accruing to the rail system operator.
Even with this extremely conservative approach to measuring the project’s potential benefits, URS estimated that the project would be economically viable in 2009 if some of those additional benefits were taken into account – and by 2019 it would very much be economically viable. An upgrade to Britomart by 2009 was anticipated when the report was written (that has been fairly accurate as we are now upgrading Britomart to handle an extra six trains an hour through bi-directional running) and then again by 2021 (the full tunnel construction) due to rising patronage.
Of course, this analysis was based on a $500 million construction cost, and if the cost is now $1.5 billion then the project will need to have three times its previous benefits to still be economically viable. However, I very much do think that this is possible because a huge number of benefits were ignored by the previous analysis. For example, in ARTA’s Auckland Transport Plan it was mentioned that the CBD Rail Tunnel could provide $2.4 billion in benefits through “releasing the economic potential” of the CBD and other inner suburbs on the railway system.
All in all, I think it’s interesting to get the full picture of what work has been conducted previously on this critical project. It will be interesting to see what the current study concludes with regards to alignments, station locations, costs and – most importantly really – the final economic analysis of the proposal. I do hope that a wider economic analysis is undertaken, so that the significant wider benefits of the CBD Rail Tunnel are included.