As I pointed out last week, making sensible mode decisions is about matching the mode to the demands of the corridor. In Auckland’s case, light rail along Dominion Rd appears to hit the sweet spot between coverage, demand, speed and capacity.
However, the revelations over the last few weeks have suggested that the priorities of the government have changed. That instead of getting the best overall outcomes, the focus has shifted to getting to the airport as fast as possible, something I call Airport Derangement Syndrome. It also appears the NZ Infra proposal at least is suggesting using a light metro type system similar to Vancouver’s Skytrain. The big advantage of light metro is that by being fully automated, services can run very frequently throughout the day. Trains on these systems can be as little as 90 seconds apart giving them significant capacity but the downside is they need a dedicated corridor so can be expensive to construct.
In this post I thought I’d look at the question of “if fast light metro is the answer, are we looking at putting it in the right place”.
First, some assumptions:
- This is not just about providing a connection to the airport but also providing a new rapid transit line through the isthmus, thereby expanding the rapid transit network as opposed to just adding an airport station.
- There are four key corridors between the existing rail corridors, Sandringham Rd, Dominion Rd, Mt Eden Rd and Manukau Rd. These will be the ones I look at as the assumption is any tunnel would largely stick to road corridors where possible.
- The route from Onehunga to the airport will be the same for each option – alongside the motorway corridor.
- As light metro requires a complete grade separated route and as both surface and elevated routes are unlikely consentable, that through the isthmus it’s going to require expensive tunnelling.
Let’s look at some of the factors.
One of the key reasons for Auckland Transport looking at light rail in the first place was to find ways to reduce bus numbers in the city centre. Key corridors such as Symonds St are already over capacity and this prevents us from running more buses. Replacing a lot of buses from a busy route with light rail would then free up space for more buses from other routes. The Central Access Plan, which was what recommended light rail, says an “internationally accepted level for reasonable operation of 80 buses per hour and an absolute limit of 140 buses per hour“.
So I counted up the number of buses that arrived in the city centre that use Symonds St based on the hour in which they arrived in the city. At peak times there are around 108 buses an hour between both 8-9am and 9-10am. The four central isthmus corridors are the biggest contributors to this and the number of buses from each of these are shown below:
I was surprised that Sandringham Rd is the highest and also that it peaks after 9am. Dominion Rd is not the peakiest route but it does have the most buses throughout the day with about 50% more buses overall.
If we’re going to invest a significant amount of money on a a high-capacity light metro system, we need ensure that it gets a lot of use. While we would expect such a system to encourage more people to use public transport, current bus usage can give us an indication for how busy each of these respective routes could be. Using some data provided by Auckland Transport, I’ve estimated the annual usage of services on each of these corridors. However there are a few things to note:
- This is just the total number of boardings and is not adjusted by location so might include trips outside of where light rail/metro would run e.g. a student going to Lynfield College.
- For trips from the southern isthmus it would introduce the need to transfer which may have a negative impact on PT use in those areas – although they would be transferring to a faster service and we know that people will transfer for this e.g. at Newmarket many Western Line passengers heading to Britomart will transfer to a Southern Line train also going to Britomart just to save two minutes.
- The Outer Link also runs on Manukau Rd for a significant section. I’ve made an estimate of the level of usage for this section.
Dominion Rd buses are by far the most used with close to 3.2 million trips annually on them compared to 2.6 million on Mt Eden Rd and Manukau Rd with Sandringham Rd seeing 2.2 million. As a quick comparison, the NX1 buses have 4.9 million boardings and the NX2 buses have 2.9 million.
I’ve also broken the usage down by weekdays vs weekend days. Most notably here Manukau Rd has a higher proportion of use on weekends.
To put this in perspective, most light metro systems are built with an expectation of over 100,000 boardings per day with many lines carrying a few times that. Auckland’s entire current rail network sees about 76k per weekday and that should at least double once CRL opens. While we certainly would get more usage from connecting a route to the airport, we’re probably talking about needing a ten-fold increase in usage.
While current bus usage can give us an indication of current levels of usage, enabling more development along the route will encourage greater usage in the future. The map below shows the zoning currently enabled in the Unitary Plan. In my view if we’re investing the kind of money likely to be needed, we should also be having a conversation about additional up-zoning but short of that, this is what we could get. First, a quick description of what the key zones allow for, although there are a bunch of other factors which can increase or decrease this. More detailed information on the zones can be found here.
I’ve added a couple of locations where we’d want stations (black circle) but there are a few other locations they could be useful.
From this we get
- Sandringham Rd – Much of the route is surrounded with THAB zoning, particularly around Balmoral Rd and at the Southern end at Stoddard Rd meaning there’s a lot of potential development allowed. What’s more, much of that THAB at the southern end is already owned by the government and can be developed by Kāinga Ora. (see map below from some of the previous work on light rail).
- Dominion Rd – Most of the route outside of the town centres is lined by Mixed Use zoning which allows for a lot of development but in most places, just back from Dominion Rd is locked in single house zoning with heritage overlays so doesn’t provide as much as Sandringham Rd does. The government does own a number of sites towards the Mt Roskill end of the route.
- Mt Eden Rd – This is probably the worst of the four routes with the only significant new development allowed at the southern end of the route around Three Kings.
- Manukau Rd – Like Dominion Rd, Manukau Rd allows for Mixed Use for much of the corridor (from Newmarket to Greenwoods Corner) but also has some decent chunks of THAB around Greenlane West and a lot around Royal Oak. The town centre zoning in Royal Oak also has a higher than normal allowing for up to eight-storeys. This probably puts it on par with Sandringham Rd for potential but it doesn’t have as much government owned land.
There will be many other things we should consider but one of the most important of those will be how it interacts with the rest of the network. For example, with the Sandringham Rd route, a station at Kingsland would provide the fastest option for those transfering from the Western Line – but there are better ways to deal with that.
The routes are kind of shown above but one difference is how they might connect to the city. In the case of Mt Eden and Manukau roads I’ve looked at running it under Wellesley St to take advantage of ‘the cross’ station that the Aotea station is designed to enable. This could also allow for a university station and for the Manukau Rd route, a station close to the Hospital. It could also see the route extended to, or end at, Wynyard Quarter before heading to the shore in the future. Because of the tricky grades through here, for Manukau Rd, it is less direct through Grafton Gully so crosses under the motorway higher up the valley.
For each of these routes we get the following distances from around Aotea to Onehunga and then the airport.
- Sandringham Rd – 12.9km / 22.4km
- Dominion Rd – 11.5km / 21km
- Mt Eden Rd – 11.2km / 20.8km
- Manukau Rd – 9.7km / 19.3km
Given tunnelling and underground stations are incredibly expensive, the Manukau Rd route being at least 1.5km shorter would save a considerable amount of money.
I’ve then run these routes through my travel speed calculator, which I’ve calibrated to match what Vancouver’s Skytrain achieves. This gives us the following travel times to the airport from the centre of the city (Aotea) with the routes taking 11 minutes from Onehunga to the airport.
- Sandringham Rd – 29 minutes
- Dominion Rd – 27 minutes
- Mt Eden Rd – 28 minutes
- Manukau Rd – 24 minutes
So because it’s a shorter, more direct route Manukau Rd almost three minutes faster to the airport than the alternatives and would be even faster than a non-stop heavy rail train, even if it was practical to build a line from Puhinui (which it’s not). As a good rule of thumb, each additional station would add about 1 minute of travel time so we could even include a couple more, such as at Greenwoods Corner and between Greenlane West and Newmarket, and it would still be faster while supporting a lot more development along the line.
Sandringham Rd has some good potential but is the longest route and effectively duplicates the Western Line and CRL for a substantial distance, which seems pointless. My guess is that post CRL we’ll see large numbers of Sandringham Rd bus uses transfer at Kingsland for a faster trip so most of the benefits from using Sandringham Rd could probably be achieved from ensuring the bus lanes along the route were improved, the services streamlined (the timetables/operating patterns are messy compared to the other routes) and that transfers are made easy at Kingsland.
I also think our crosstown light rail proposal could really help in also serving that significant potential development near Stoddard Rd and even with an extra transfer, would be faster for people from the west to get to the airport than transferring at Kingland.
While it doesn’t look like a lot, all of the mixed use lining Dominion Rd means there’s lots of potential growth there, just not as much as some of the other routes. In saying that, it probably doesn’t have enough development allowed to justify light metro but with a few extra stations it still looks ideal for a surface level light rail route that would also further enhance the local town centres.
Mt Eden Rd
It’s hard to see Mt Eden stacking up due to the lack of sufficient development allowed around it. Like Sandringham Rd, it could do with a lot better bus lanes to improve the existing route though.
If we’re going to build light metro it should probably be along Manukau Rd. It’s not only the shortest and fastest but also probably enables the most development. It’s a route that with a future extension to the North Shore would see it link up three hospitals (North Shore, Auckland, Greenlane) and six university campuses (Albany,Akoranga, AUT & UoA in the City, Grafton & Newmarket). The downside is it is similar to the heavy rail network between the city and Newmarket and of course the cost of 10km+ of tunnelling wouldn’t come cheap. To me this is still the 2040+ option for after we’ve got our current rapid transit expansion priorities (including Dominion Rd) completed.
As to why not just do that route with surface level light rail, while it is more direct, it would actually spend a longer time on surface roads than Dominion Rd so a surface version wouldn’t be as fast.
If we were to build all of the above it could give us an RTN network on the Isthmus of something like this (with an assumed North-west too).