The Mt Roskill Spur

This page originally comes from a post in November 2013.

One project on our Congestion Free Network that appears to have caught the attention of a few people has been what we call the Mt Roskill Spur. We’ve been getting some queries about it like what it is, why have it on the CFN and how much does it cost. The purpose of this post is to hopefully answer those questions. You can see it on the map below.

CFN Mt Roskill Spur

What is it?

This is the easiest of the questions to answer. It’s a short railway line that comes off the Western line between the Mt Albert and Avondale stations and ends at Mt Roskill. It would have two stations, one at Owairaka and one at Mt Roskill.

Why have it on the CFN?

Before I answer this question let’s take a quick history lesson.

Back in the 1940’s after World War 2 Auckland was starting to develop quite quickly and this was a time well before we started building our first motorway. At the time a huge amount of freight was being moved around the country by rail and that was only expected to increase. Likewise with the city growing it was realised by the railways that there was a strong possibility that there would be increases in passenger trains within the region (early incarnations of the CRL had been talked about since the 1920’s). It was realised that the growth, would put a lot of pressure on the Newmarket junction. In addition the tracks on the inner sections of both the western and southern lines are quite steep which is not ideal for hauling heavy freight trains up in a hurry.

They realised that to get freight trains destined or arriving from north across the city it would be increasingly difficult and so in the late 1940’s designated a route known as the Avondale-Southdown line. The intention was to enable trains to bypass Newmarket by cutting across the lower section of the isthmus. The designation for the line is in blue on the map below but of course was never built.

CFN Avondale-Southdown Line

You can also quite clearly see some elements of the designation in the councils GIS maps. One of the best examples is at the Avondale end where the land for the junction with the western line is clearly visible by looking at the property boundaries. I have highlighted in the image below and just in case you’re not completely familiar with it, the building with the large roof is the Pak n Save on New North Rd.

CFN Mt Roskill Spur Junction

Building the line has appeared on a quite a number of documents over the years and most recently has included the Auckland Plan and as such has been included in the Integrated Transport Programme however it is considered a third decade project i.e. sometime between 2031 and 2041. The plans do list it as being on the future Rapid Transit Network meaning it is intended to eventually carry passengers however I’ll come back to that point shortly.

Of course the line is yet to be built however within the last decade the NZTA and its predecessors have been busy “completing the motorway network” and SH20 has been extended from Hillsborough through to Maioro St with the Waterview Connection project being the piece that will like SH20 with SH16. Because the rail designation already existed it made sense for the road builders to future proof what they were doing – which was probably helped along by the fact they needed to use some of the rail designation. The short version is that as such the bridges that cross the motorway through this part have also been designed with the rail line in mind and in almost all cases the extra span is already in place just waiting for a rail line to be installed underneath it. This is perhaps most clear at Maioro St (below) where you can see the spans for the motorway between the on/off ramps while there is a completely separate span for the future rail line.

CFN - Maioro St

Because the most of the motorway bridges have already been built it means that there is much less to do if we do ever decide to build the line. That should save a heap of money and time in the long run which is always a good thing. There are two bridges which have not yet been built, one is Richardson Rd while the other is Dominion Rd. Adding the already completed bridges to that the fact that Kiwirail already own most of the corridor and it means that it should bring down the cost of  building the line substantially although admittedly I’m no engineer. The Road crossings that would need to be addressed to enable a train service like we proposed would be New North Rd and Richardson Rd.

So why the spur?

Well if you look at the second image you can see that to get back to down to sea level from Hillsborough the rail line curves and weaves through the suburbs to the north of Onehunga, well away from the existing rail network. Further while the line is designated and Kiwirail own many if not all of the properties needed, I personally can’t see the residents of these houses being all keen on a rail line going in nearby and I can see them fighting any construction regardless.

Other plans have suggested that the route down to Onehunga might follow SH20 all the way however getting down from Hillsborough is extremely steep dropping by about 60m over 1.5km which would probably be far too much for trains to handle. Further designing and designating a new route down to Onehunga is likely to take an extremely long time and cost a lot of money. So the question we asked is whether there is anything we can do to make use of at least parts of the existing designation without having to wait for the whole thing to be completed. The Mt Roskill Spur was the answer.

What benefits does it have?

There’s no point in building something just for the sake of it and so the next question is if there is any logic in building this line. We think there is. There are a number of different options for how we run trains after the CRL has been completed and one of the options is a three line system where each of the long lines (West from Swanson, South from Papakura, East from Manukau) are paired up with a short run elsewhere on the network. One of the key reasons for this is that joining long lines together (say west and south) makes for a very long route which can suffer from reliability problems as delays can be amplified along the route.

The long and short pairing helps address that somewhat while also being useful in providing additional services on the inner sections of each of the lines which is where the most passenger demand is going to be. The Onehunga line already serves this function on the southern line. This extra capacity is likely to be especially important on the inner western line which would suddenly become much closer to the CBD following the completion of the CRL and likely to see a significant boost in patronage. So it effectively helps to balance out the rail network while also providing additional capacity on the existing lines. You can see that AT has been thinking about exactly this from this image on their CRL page which shows the rail network as a three track system. We’re suggesting sending either the red or green route to Mt Roskill.

The second and most obvious benefit is that it would provide two new stations on the network in what are fairly residential areas and the land surrounding the proposed Owairaka station (which would be between Richardson Rd and Maioro St) has zoned to allow for a town centre and the surrounding area has a decent amount of Terraced House and Apartment zoning in the Unitary Plan. It is one of the higher density zoned places in the old Auckland City area (should have been a lot more).

CFN - Owairaka Zoning

 There are also some potentially large benefits to buses. We already know that the Dominion Rd buses can get very busy at peak times and it is one of the most popular routes in the city. These routes are only like to get busier in the future as PT becomes more useful overall. Yet at the same time we know from the City Centre Future Access Study that space within the CBD is going to be extremely constrained due to the number of buses from other areas. That is after-all one of the key reasons for needing the CRL.

This spur helps to improve that situation as the two stations are passed by three different Frequent bus routes (two on Dominion Rd and one on Sandringham Rd). While the rail network goes in the “wrong direction” for a little bit, it will likely be slightly faster from Dominion Rd through to the centre of the CBD so that gives bus passengers the option of a quick transfer to the rail network for a faster journey. Not all will do that but it is likely some will and combined with the patronage from those living in the vicinity of the stations are likely to reduce the pressure on buses, especially on Dominion Rd meaning more space on them for people closer to town.

Some have asked why not extend the line all the way Hayr Rd which also carries a frequent bus route. That could be done perhaps a bit later however by my calculations the rail network isn’t as competitive from a time perspective and there would be the added cost to get the line under Dominion Rd. The map below shows the proposed frequent routes in the area.

CFN - New bus network interaction

So hopefully I’ve managed to explain why it is potentially such a useful but of course the cost is the big question.

How much does it cost?

This is the area where we have had to speculate the most however here are some estimates.

Railway Junction – The Newmarket junction was recently upgraded at a cost of about $50 million however that is much more complex that what is needed here. We’ve estimated $25 million.

New North Rd – This would have to be grade separated so once again we have allowed $25 million for this.

Richardson Rd – While the rail span hasn’t been built yet, it has been designed for so can probably can be done for $10 million or less.

Stations – We don’t envisage the two stations needing to be major ones like say New Lynn or Newmarket but a typical suburban station instead so probably $5m each so $10 million combined.

Tracks – Because the corridor already exists and has been grade separated we expect that the tracks should be able to be laid much cheaper (per km) than other projects. The complete rebuild of the Onehunga branch was in the vicinity of $10 million while the new Manukau branch cost $50 including the station in a trench. As such we think it should cost ~$80 million.

All up that gives us a cost of about $150 million.

I think the rail spur proposed above would be a very useful addition to our network after the CRL is constructed. Not only would it be fairly quick and easy to construct, it would also offer a speed advantage over catching the bus (and probably driving) for those currently living in the southern part of the Auckland isthmus and it would help ease pressure on the need for us to keep adding more and more bus services, by shifting those trips to rail. It would also be likely to significantly ease congestion along both Sandringham and Dominion Roads if the service was attractive enough. A pretty useful “low hanging fruit” I think.