The Southern Airport Line: Why it is Bus or Light Rail Rapid Transit Not Heavy Rail

More information on the Southern Airport Line


One of the most frequent questions I am getting about the Southern Airport Line (see: How Do the Northern and Southern Airport Lines Work? A Short Redux into the twin Airport Lines) is why not heavy rail from Puhinui to the Airport.


Greater Auckland has covered the issue numerous times. Below are two extracts on the logic why the Southern Airport Line is suggested to be either Bus Rapid Transit or Light Rail Transit:

Since Auckland Transport and NZTA decided in the middle of last year to rule out Heavy Rail as the best way of serving the Airport with rapid transit, there has been a lot of ongoing consternation from many about this decision. The comments threads on posts about this topic are always long, sometimes enlightening, but also a lot of people seemingly talking past each other.

In general, it seems that most people broadly accept that a heavy rail link to the Airport from Onehunga is too expensive and too difficult. There remains some discussion about whether extending rail from Otahuhu is a viable option – Patrick blogged about this once – although many of the cost issues would be similar to the Onehunga option and the impact of such a route on housing in the area seems like it would be very significant. But most of the talk is about whether a route from Puhinui might be the best idea, this is also a common comment we see in other media. This was looked at in earlier phases of the Airport Rail project, with a few different alignments being examined:

Source: Greater Auckland

As a branch line off the current Southern Line, presumably if you built this option then either some trains that are currently heading south along this line will either head to the Airport instead of their current destinations of Manukau or Papakura, or further services would need be added. This would mean something like what’s shown below:

Source: Greater Auckland

This option obviously throws up a few questions:

What are the implications of running more trains on the southern line?

This is already the most constrained part of the rail network. Both the southern & eastern lines overlap between the Westfield and Wiri junctions, but these passenger services also overlap with the busiest section in the country for freight trains as there are shuttles from the Port of Auckland to their inland port at Wiri plus longer-distance trains heading to Tauranga or south of Hamilton. Clearly we’re going to need four-tracks along this whole section for this to work.

Furthermore, even taking freight out of the equation (say through dedicated tracks), there is still only so much capacity available across the rail network – CRL can increase this but only to a point. With Manukau already on its own branch line, another branch to the airport will mean we inevitably have to choose between running a limited number of trains to either the Airport, Manukau or Papakura. In effect, do we want three averagely serviced routes or two well serviced routes and with the way ridership continues to increase, we’re going to need all the capacity to Manukau and Papakura we can get in coming years.


Source: Greater Auckland


And this:

Below is a post I wrote in August 2016. We are re-running it now because it is confirmed what we have learnt since from both the seemingly endless number of reports on this issue and the increasingly dysfunctional traffic in the area. Here is my proposed way forward for this issue, in order:

1. The first step: While designating the Light Rail route, build a Rapid Bus service between Puhinui Station and the Airport with minimum 10 frequency.

Replace the current Airport inter-terminal service, and extend it to the Airport Business area on Tom Pearce Dr, along SH20B on new bus-only shoulder lanes to Puhinui Station. Puhinui upgraded to Interchange Station status, all weather, safe, optimised for transfers. There are already 5min train frequencies here both ways at peaks, which is when traffic is worst in Airport area (see chart below). That is a train in one direction or other every 2.5 minutes! Other than the station upgrade, no other rail investment is required for every train on the Southern and Eastern lines become a ‘Train to the Planes’. This should be done as soon as possible, there seems to be available land at the Station could it be operating by end 2018? Extend this over the rail line and on to the new Manukau City Interchange Station too.

At the same time optimise existing bus lanes on Dominion Rd as an immediate capacity and quality improvement for those services, while getting on with designing the proposed and agreed Light Rail system there and to the city.

2. Construct Light Rail as planned to run from Wynyard Quarter, Queen St, Dom rd, Mt Roskill, Onehunga, Mangere, Airport. <2025. While also extending the Rapid Bus east to Botany to connect with AMETI (busway from Botany to Panmure)

3. Rapid bus could become converted to Light Rail if justified, certainly cheaper and easier with Light Rail at Airport already; becomes an extension or overlapping route; Airport no longer a terminus.

Multiple routes and modes to and through Airport, Isthmus, South West, and East. All staged, each part accumulative and mutually supporting, nothing redundant.

Through-routing and choice, a one seat ride on Light Rail through a dense part of city all the way through the City Centre’s spine to the big Transit interchange at Downtown. With options to transfer to Rail network at Onehunga, K Rd, Aotea, and Britomart. Ferries at Britomart. But also an efficient option east either all the way into the south-eastern heart land or again to transfer to two rail lines at Puhinui for South, North, and inner Eastern destinations.

Below is the map from last years Government and Council Auckland Transport Alignment Project. Note route from the Airport east to Botany via Manukau City.

Source: Greater Auckland

4. After 2023, with the City Rail Link open freeing up platform space at Britomart, and at least one additional track on the main line enabling new services through the city, then Intercity trains from Tauranga and Hamilton could be re-introduced. We will write more about this in future posts. For now it is enough to say that these would stop at Puhinui too, taking advantage of the Airport Shuttle. And this would offer both an express service from Britomart and direct Airport access for people travelling from Waikato and Bay of Plenty.


Source: Greater Auckland


Greater Auckland and I have been saying pretty much the same thing. The Southern Airport Line starting with Bus Rapid Transit give the best bang for buck while the Northern Airport Line is being built. Through time the Southern Airport Line is extended out to Botany and eventually becomes light rail as demand allows. This is why Labour have announced the Southern Airport Line as the first project off the rank alongside the North Western Light Rail Transit line (see: Labour Wants to Get Auckland Going – Southern Airport Line Committed To)


I hope this helps answer a few questions for you.


AT’s proposals for the Botany Line to the Airport
Source: Auckland Transport


Key Move 5. Part 6
Source: Panuku Development Auckland