There has been renewed discussion of a southern rail connection into Manukau Station over the past few days. The catalyst for this discussion seems to have been the Council rejecting a funding bid by Auckland Transport to double-track the north-facing rail connection, with a possible reason for the rejection being some confusion about the proposed north-facing connection and the much desired south-facing connection. If you’re not quite sure what I’m talking about, hopefully the diagram below resolves any confusion, with black showing the existing rail links and red highlighting the missing, but future-proofed, southern link:There is something intuitively logical about having the southern link in place, when you think about Manukau’s role in Auckland as the commercial hub for southern Auckland. For a start, Manukau station is likely to be the destination of more trips than it is the origin of them – because of the proposed (although now on hold) tertiary campus, the shopping centre and the employment in the area. Once the bus station is built that might change to some extent as people catch a feeder bus and then transfer onto the train. But even then I think as many people are likely to be connecting between buses or simply catching a bus to Manukau as they are to be making bus to rail connections. In summary, at least in my mind Manukau city probably serves the area to the south of it more than to the north of it, so providing a rail connection to the north but not one to the south seems counter-intuitive at best – rather silly at worst.
However, looking at how Auckland’s rail network will function in the future the north-facing link at Manukau starts to make a bit more sense – enabling Manukau to become the southern terminus of the eastern line while southern line trains (i.e. those going via Newmarket) will bypass Manukau and head further south. Certainly as I understand it, that will be the post-electrification service patterns with 6 peak trains per hour on the three main lines and two on the Onehunga Line:So there’s a logical role for a north-facing connection at Manukau in our future rail network. But how might things work in terms of providing a southern link? In my mind there are a couple of options:
- Continue the eastern line trains from Manukau south to Papakura and potentially onto Pukekohe
- Run a shuttle train from Papakura/Pukekohe to Manukau with the train terminating there and returning to Papakura/Pukekohe
Let’s look at each option in turn. Firstly with the proposal to continue to run eastern line trains from Manukau to Papakura or Pukekohe. This option would effective mean that the trains simply “detour” from the main trunk line into Manukau before returning to the trunk line and continuing their journey – much like how the 233 bus along Sandringham Road detours down St Lukes road to the mall before returning to Sandringham Road and continuing its journey. The option is shown below as an edit to the earlier diagram: It’s hard to know exactly how long the detour would take but to be reasonable there’s probably a couple of minutes in, then a couple of minutes for the driver to change ends and then a couple of minutes out – perhaps a six minute detour overall, fairly significant.The other disadvantage of this option is that you potentially end up running more train service south of Manukau than you actually need – because you’re running both southern and eastern line trains (with 6 tph on each) all the way down to Papakura. I’m not entirely sure of the loading profile on Auckland’s trains but it seems that most lines slowly build boardings at they head towards the city (the Western has a couple of blips at New Lynn & Mt Albert due to school kids) with maximum loadings on the eastern between Orakei & Britomart, the southern just south of Newmarket and the western just before Grafton station. Needless to say, we’re unlikely to need 12 trains per hour just north of Papakura.
The other option is to run a shuttle between Papakura/Pukekohe and Manukau. Immediately this seems like probably the more viable of the two options – because post electrification the current plan is to run a shuttle train between Papakura and Pukekohe because the wires are only going as far south as Papakura. Extending the shuttle train north to Manukau would provide a service that makes use of the southern link – something like this:
I will get onto analysing the likely cost-effectiveness of extending the shuttle northwards in a minute, but the initial obvious problem with this option is the question of what to do once electrification is extended to Pukekohe – as is currently proposed to occur potentially in the not too distant future. Then we won’t have a diesel shuttle at all – in fact we shouldn’t have any diesel trains on the entire rail network – and therefore this interim solution no longer makes sense and we’re back to either the first option or continuing the shuttle as a duplication of the newly electrified direct service into town. In fact those are pretty much the same thing, come to think of it.
In any case, I think we need to look a bit closer at the cost-effectiveness of additional rail service south of Manukau if we’ve made the decision to not inconvenience those wanting to bypass Manukau (i.e. those travelling from Papakura to Newmarket or Britomart) by forcing them to detour into Manukau. For the shuttle option in particular, we need to look at whether it’s worth running the extra service kilometres between Papakura and Manukau for the number of additional passengers likely to catching the train. In essence, our potential “market” for the southern rail connection are the stations of Homai, Manurewa, Te Mahia (which mysteriously isn’t shown in the RPTP maps), Takanini, Papakura and Pukekohe. In particular, I guess the key point is what would a train service from the south to Manukau offer which is superior to the proposed bus network in the south:The map above is the proposed 2016 “all day network”, with lines in red indicating the rail system, blue indicating “frequency services” which will run at least every 15 minutes 7am-7pm, every day of the week and the green lines indicating the connector/secondary network that will operate at least half-hourly most hour of the day, every day of the week.
It’s a bit difficult to pick out routes individually but overall it seems like most places are covered fairly well by the all-day network (this is supported by a number of lower frequency routes not shown above) and it also seems like pretty much all the routes feed into Manukau city at their northern end. In other words, pretty much anywhere within walking distance of one of the train stations which form the ‘market’ for a southern connection into Manukau is already proposed to be served by a fairly high frequency regular bus service doing the same thing. Everywhere outside the walkable catchments of the train stations also manages to be served by these bus services that can take passengers to Manukau (which is why we wouldn’t want to do away with those services) as well as feed passengers into the rail network if they want to take trips to areas north of Manukau.
I think I’m finding myself coming to a couple of conclusions here. The first is that Manukau is simply in the wrong place. The idiots who chose to build a new city centre a few kilometres east of the railway line create a geometrical problem that is incredibly challenging to fix – do you divert trains away from where seemingly most people want to go in order to serve the important centre or do you terminate trains at the important centre, creating inefficient outcomes or missing connections?The second conclusion here is perhaps a recognition of the different roles of buses and trains in the public transport network. To over-simplify a bit, trains work well for longer-distance trips where speed and capacity is of the essence – but at the cost of coverage. Buses work really well for shorter trips because it’s much cheaper to spread them out and cover a wider area, yet they’re pretty slow and relatively low capacity so you don’t want to be running them on incredibly long and high demand routes because that becomes inefficient.
As a result of this second conclusion I think that there is a way to make a southern connection to Manukau work because there are important trips for it to serve – quite long distance trips where speed is important and coverage perhaps less important. That is a shuttle between Pukekohe and Manukau – however I think it is only after the significant greenfield development occurs between Papakura and Pukekohe and we see new stations at Paerata, Drury and perhaps somewhere between the two. Until then I think buses can probably do a better job at providing connections between Manukau and the hinterland to the south than a train can – and probably for a much lower cost.