The one transport project we tend to follow on this blog more than any other is the City Rail Link. That project is now ticking along and Auckland Transport are proceeding with the designation but another important project has also been going on fairly silently in the background, rail to the airport. It is currently being investigated as part of a whole package of works that includes what roading upgrades are needed and used to be known by the awkward to pronounce acronym SWAMMCP which stood for South Western Airport Multi Modal Corridor Plan. It has had a change of name which I believe was largely focused on making it easier to pronounce so is now called SMART or South-western Multi-modal Airport Rapid Transit. Acronyms aside, we haven’t heard a lot lately about what is happening so here is what the latest board report said about it:
Work continues on route alignment and station options for the rapid transit elements of SMART as well as the roading (including cycling and walking) alignments. Phase 2 is scheduled for completion in December/January 2012/13.
The last few reports have actually said the same thing and I suspect that it might not be for a few months after that we actually see what is proposed however we can probably make a bit of a guess. Unless the current study has come up with a new outcome we will probably see a refinement of the option that came out of a 2008 study on the issue. At that time it recommended a loop that was built from Onehunga south to the airport then heading east to Puhinui to connect with the existing southern line, as is shown below in blue.
Now while it would be nice to build the thing all in one go, I think the reality is that even with a supportive council and government we will only be able to build one of the links so for this post I thought I would look at some of the pros and cons of each.
This would see the Onehunga line extended south over the Manukau harbour on the way to the airport.
- The line would effectively be just an extension of the Onehunga line (which is due to be duplicated as part of the works for the CRL). This means that effectively services could be run without putting any additional pressure on the existing rail network.
- The suggested route from Onehunga passes through a number of potential locations for stations on its way to the airport. These are Mangere Bridge, Mangere and the industrial area around Montgomerie Rd. Stations in these locations would help to provide additional patronage on top of those that are just going to the airport. Stats NZ suggest that by 2040 there will be about 40,000 people living in within a short distance of the rail line. This makes it much more a line for the south west of the city rather than just an airport line.
- Once the line got across the harbour there is the ability for it to be staged so that some of the benefits of the line could start being achieved earlier or construction could be stopped until we had the funds to complete the line i.e. we could build the line to Mangere town centre then hold there for a few years until more funds became available. This could be crucial, especially if funding is tight.
- As the route is slightly more direct, it would be a little bit faster than the Puhinui option for a trip to town.
- The biggest issue with building a line from Onehunga is the cost. The 2008 report suggested it would cost $707 million vs a link from the east at $471m
- The recently build additional harbour crossing has been future proofed to have rail lines on it but there would likely still be quite a cost to actually put it in. There is also quite a bit of development near the previously suggested corridor which means there may be a need for substantial property purchases.
This would see a branch line heading west from the area around Puhinui all the way to the airport. It may or may not be linked up directly to Manukau.
- The biggest thing in the favour of this option is the cost. The figures in the 2008 document suggest it would cost around $470 million, around 1/3 cheaper than the Onehunga link option.
- The route is largely over green field land so much less impact to any communities and businesses.
- It also provides rail access to the airport for those from the southern suburbs.
- While it is cheaper to build, it also has much less patronage potential as there are no other stops other than the airport.
- It is unlikely that trips by travellers to/from airport alone will be able to support enough passenger trips alone to make building the line worthwhile.
- Perhaps the biggest problem with linking only to Puhinui only is that it forces yet another line on to the tracks between Puhinui and the Westfield Junction. That line is already pretty busy with lots of passenger and freight trains so trying to squeeze more trains on would really affect the capacity of the other lines.
Ideally I think we need to consider building the whole line so that we can get the most benefits out of it. If we had to pick one option then I think it needs to be the from the north simply due to the greater potential that it provides . This is of course just my opinion but if we were to be faced with a one or the other decision, I’m keen to hear what you think?