A lot of discussion around Auckland’s rail network is focused on large and very expensive projects. Much of this is justified as the next obvious places to expand the network (the City Rail Link, Rail to the Airport, a North Shore Line and a possible Southeast Route) will bring huge benefits, but at significant financial cost. Out of the projects listed above, the City Rail Link is an obvious standout as essential for its ‘enabling’ of higher frequencies throughout the whole network – but beyond that project perhaps we need to start thinking about further low-hanging fruit to take advantage of this increased capacity.
Once the City Rail Link is completed, the latent capacity of the entire network is ‘opened up’, and the train frequency constraint of one every 10 minutes along the main lines is relieved. While, if money were no object (and theoretically it isn’t, if we can make some tough choices and not proceed with some eye-wateringly expensive motorway projects), a full Airport Loop via Onehunga, Mangere and through to Manukau is the next obvious project, there is another project that may well be worth investigating. And that is making a start on the easy part of the Avondale-Southdown Line.
The Avondale-Southdown Line is a rail corridor that has been designated for over 60 years now, originally envisaged as a freight bypass of Newmarket that has never quite gotten around to being needed. In a passenger sense, the line is a bit of an oddball – serving more the cross-town type of trip than what rail has traditionally been most popular for. The blue line below shows its approximate alignment:Importantly, because the designation is in place, both the Mt Roskill motorway extension and the proposed Waterview Connection project have had to provide for the corridor – building longer bridge spans, often doing earthworks to retain the rail corridor and other works. By the time the Waterview Connection project is completed, there will be a pretty well defined corridor between New North Road in the west and Hillsborough Road in the east, almost “ready to go” for laying tracks and putting up wires.
East of Dominion Road, the future alignment of the route is somewhat uncertain, because the current designation (which takes the tracks through a residential part of Onehunga) is seen as an unlikely route compared to taking the line along the motorway across Onehunga Bay. This would mean trenching/tunnelling under Hillsborough Road (because of the steep grades) potentially extending quite a way towards Dominion Road, which means a whole lot more money. So if we’re looking for “low hanging fruit” we probably don’t really want to go east of Dominion Road.
Which leaves us with a branch line off the existing Western Line, extending for about 3.5 kilometres – with two additional stations: that I have called “Owairaka” and “Mt Roskill”:First things first, it’s important to note that this branch line is not feasible until after the City Rail Link has been constructed. Until this project is complete, the Western Line has a capacity of 6 trains per hour (plus any that don’t go into the city), and it would be silly to split that capacity off when much of the Western Line’s patronage comes from west of Mt Albert Station.
However, post CRL the Western Line’s capacity becomes significantly increased and we could potentially run something like four trains per hour along this branch, six trains per hour along the Swanson-city centre section, overlaid to provide 10 tph between Mt Albert and town. I’m not quite sure how this would fit into previous service pattern diagrams that I’ve drawn up, but we could find a way of making it work.
I suppose the next obvious question to pose is whether services along this branch would be popular or not. Obviously compared to Sandringham Road and Dominion Road bus services, the rail line would be taking a fairly indirect route – swinging much more to the west before heading into the city. But of course at the same time it’s a rail line (and the new section could presumably be built to quite good alignment standards allowing for fairly high speeds) which means it can bypass congestion.
To get some idea about how timings might compare between catching a train or a bus from either the Owairaka or Mt Roskill stations, I first looked at the average speeds of trains along the Western Line that is expected after the City Rail Link has been completed (using this table from the CRL business case). A number of trips indicate an average speed of around 30 kph, which suggests that Owairaka to Aotea (9.83km) could be done in just under 20 minutes while Mt Roskill to Aotea (11.58km) would take just over 23 minutes. I think both timings are fairly conservative as the new section of track should allow for much higher speeds than is currently possible along the Western Line.
In comparison, most Sandringham Road buses that pass around where the Owairaka Station would be located seem to take 30-40 minutes during the morning peak to travel into the city. Even the 7.48am 243 express bus takes 42 minutes to make the trip. So catching the train would offer a significant time advantage – even taking into account a 7 minute wait at peak times (average wait if we offer 15 minute frequencies). Turning to Dominion Road, timetables indicate a trip length of around 30-35 minutes from Mt Roskill shops into town and about five minutes longer from May Road for services travelling from that direction. This once again indicates a time advantage for rail, although perhaps not to quite such a significant extent.
One thing to take into consideration in all this is how these two stations might be useful in helping to reduce the number of buses that will feed into downtown from the southern isthmus in future years. We know from looking at NZTA’s passenger transport study into the Waitemata Harbour Crossing project what the bus numbers along various key arterial routes will be in 2041 in both the “with CRL” and “without CRL” scenarios. I have bundled together the key data from those maps into the table below:The “Symonds Street (over CMJ)” numbers are of most interest to this particular rail line, because they include Sandringham Road and Dominion Road buses (along with New North and Mt Eden road services). We see from looking at the table above that while the CRL makes some difference (162 buses per hour rather than 244), even in the “with CRL” scenario we end up with almost a tripling of bus numbers: up from 56 at the moment to 162.
If we realise (as I outlined in this recent post) that there’s really no way the city centre can handle as many buses as is being proposed for it even in the “with CRL” scenario, then decreasing the number of bus services from places in the southern isthmus by shifting them onto rail starts to make a lot of sense. Perhaps most bus services south of our two new stations would be regular feeder services to those stations, with passengers given the choice of continuing along regular bus services to the city, or shifting onto the train.
All up, I think the rail spur proposed above would be a very useful addition to our network after the City Rail Link 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.