Rail services – post CBD tunnel
Amid a rather large amount of discussion surrounding the CBD Rail Tunnel that I’ve had over the past few days has been a focus on how having that tunnel operational would affect rail service patterns. The diagram below shows the current three lines that we have in Auckland: Green being the Western, Red the Southern and Yellow the Eastern Line.
In the not too distant future we will have the Onehunga and Manukau Branch lines operational, and eventually 10 minute frequencies on the three main lines once electrification is completed in 2013. At that stage the services will work something like what’s going in the diagram below – with the blue line being the additional Onehunga branch line.
It’s pretty easy to see from the above diagram why the CBD rail tunnel will be necessary in the next few years – with all these four different lines converging on Britomart with its two-track tunnel being the only way in and out of the station.
The CBD rail tunnel provides us with the opportunity to significantly ease the pressure on Britomart as the ‘choke-point’ for the network, as it would be possible to “through-route” many existing services. Some services are likely to keep their current routes even after we have the CBD Rail Tunnel – such as diesel trains on the Southern Line coming from Pukekohe and diesel trains on the Western Line coming from Huapai or Waimauku. But if we set those services aside for the moment, we could simplify things enough to actually only need two different lines for Auckland:
- A southern and western line (shown in red below). This would operate from Swanson to Papakura via the tunnel.
- An eastern and Onehunga line (shown in green below). This would operate from Manukau City to Onehunga and could eventually be extended back to Manukau via the airport to form a pretty giant loop.
Then we just need to build the North Shore Line, the Howick Botany Line, the Avondale-Southdown Line and we’ll have a pretty fantastic rail network.
The last image is the obvious choice in my opinion, something I came up with myself years ago when I first read the URS tunnel report.
I think a lot of people (such as Johnston on bettertransport) are expecting something like the second image, except where all four lines go around some kind of loop…. wasteful and awkward if you ask me.
The most recent study by ARTA supported completing the full airport link to Auckland and Manukau and the line between Avondale and Onehunga at the same time. If this was done then it could simply be the case of adding a third line looping around the ithsmus and through the tunnel also. This would also have the benefit of having every track on the ithsmus carry two lines, so with a ten minute frequency you’d have five minute frequencies on the doubled sections (and most of the southern line)… not to mention a train every 3-4 minutes through the CBD tunnel. This would also be about the limit of the tunnel’s capacity, so you would have an efficient and cost effective metropolitan rail system.
I see having the services turn around on themselves through the loop and head back the way they came as a pretty massive lost opportunity. Only 12% of the Auckland region’s jobs are in the CBD, so we need to make the rail system useful for more people than simply those living in the CBD. That means that it needs to work for those travelling from Avondale to Ellerslie, or vice-versa. I think linking the lines up achieves that.
I would still see the advantage of some Western lines continuing South directly via Newmarket and thereby bypassing the CBD all together. Would benefit those not working in the CBD and shave a bit of time off an Avondale to Ellerslie trip for example.