On the agenda for this weeks Transport Committee meeting there is a notice of motion being put forward b George Wood in regard to the southern link at Manukau.
If you don’t know what the southern link is, it is in the image below:
Basically when the Manukau branch was built, it was only constructed with a link to the north however as part of the motorway construction, the NZTA designed the bridge that spans the motorway so that a southern link could be built in the future if needed. Now the thinking for most people is along the lines that as most people who work or visit Manukau come from south of the area then we should build the southern link and at first that seems to make sense but as you look into the issue closer things aren’t so black and white. The first thing we need to consider is how we would run services that would make use of the link.
The first option is that we send some or even all trains heading south into Manukau first and then back out and on south to Papakura. The issue with this of course is that even with electric trains, it would add around 7 minutes to the journey time for anyone who catches the train from south of Manukau to points further north. The other option is a shuttle type service that runs from Manukau to Papakura or perhaps even Pukekohe once electrification has been extended. If we had to choose one option then the second one would be best as it doesn’t inconvenience existing users but the thing is, we are unlikely to be able to justify such a shuttle at anything more than a 15 minute frequency.
There are a couple of reasons for this. First, the entire urban population south of Manukau is only around 100,000 people and for what is a fairly short journey the only ones who are likely to consider doing using the rail line are those that actually live very close to the station. Further feeder buses in this part of town will mostly flow through to Manukau anyway and there will be an interchange with the station so for most it even with the link in place it would probably still be quicker to stay on the bus than transfer.
Next there isn’t actually a massive amount of employment that isn’t already served by the existing stations. In the map below the entire area contains about 26,000 jobs yet as you can see many of them are already just as close to either Puhinui or Homai. Manukau itself might only have about 10,000 jobs.
Lastly and perhaps most importantly are the costs. Obviously to we would need to pay to build the link and I’m not sure how much that would cost but to run such a train service, would likely require at least 3 additional EMUs to be purchased and operated just for a service to Papakura. Each EMU costs about $7.5m and was estimated in the CRL business case to cost close to $400k to run (although the MOT felt this was undercooked in their review). Including purchase costs, over a 10 year period it would cost over $30 million to provide such service. That money could easily be instead used to provide a substantially better service on the existing bus routes that would benefit a much larger proportion of local population.
All of this doesn’t mean I think it should never be built but before we do we need to consider all of the options. It also really highlights one of the key problems with branch lines in that services have to be split off or extra services run at great cost. Perhaps this situation also highlights the different roles of buses and trains quite nicely. Buses are great for service coverage at relatively low cost and for short trips. Trains are good for high-demand long trips where the focus is more on speed & capacity and less on coverage. Trips between Manukau and the north are likely to be longer than those between Manukau & the south so there’s a logic in the trains focusing more on serving trips linking Manukau with the north than those linking it with the south.
Perhaps when we electrify to Pukekohe and if we open up some of the land between there and Papakura it might be the time to reconsider this but until then, I feel that putting the link it will waste our scarce PT funds that could be better used else where.