On Saturday, the Herald raised the issue of how light rail to the Northwest will reach the city.
The Weekend Herald can reveal that the suburbs of Pt Chevalier, Grey Lynn, Arch Hill and Karangahape Rd are on the route being considered by the NZ Transport Agency.
The route is part of a light rail project – the modern day version of trams – from the CBD to West Auckland.
The option of taking trams off the northwestern motorway at Pt Chevalier and running them along Great North and Karangahape Rds is the third big change in as many weeks to a $10 billion public transport programme of ‘Think Big’ proportions in Auckland.
The key phrase here is that it is being considered. That the NZTA are doing this isn’t at all surprising as since taking over the delivery of Light Rail from Auckland Transport, they’ve have been reviewing most aspects of it. And in the case of the Northwest, AT had previously been looking at busway options for it. But I suspect that after ‘considering’ the options, they will most likely prefer the motorway option for light rail. So I thought I’d look at a few of the reasons why the motorway corridor might be best.
How does it integrate into the wider PT and transport network
In thinking about what corridor we use for light rail to the Northwest I can’t help but think, Why not both?
In Auckland we became accustomed to trying to have one route do everything, usually ending up doing each of those things poorly. The new bus network has helped to reset that and so as we move into a new era for PT in the city it gives us the opportunity to think more about how we develop our PT network.
To me, the primary purpose of light rail is to unlock and serve the huge growth expected in the Northwest in the coming decades. But there is also significant development occurring along Gt North Rd though Grey Lynn and it’s quickly becoming a busy and dense corridor. A corridor that’s going to need a more localised level of service than, in my opinion, we should look to provide with light rail.
Fortunately, we’ve already got a really good service that serves Gt North Rd in the 18 bus route between New Lynn and the city. That could be further enhanced by better bus lanes, stops and even buses (electric ones) as part of making Gt North Rd a great multi-modal boulevard. That would then leave Light Rail on the motorway to provide a faster, more direct service for longer distance passengers, almost like an express service if you will.
Perhaps one way to think about this issue is to think about what corridor would be best if instead of building light rail, we were building a busway?
Speed vs coverage
With all transport there’s always an inherent trade-off between speed and coverage. In this comparison, the routes are both of a fairly similar length with the motorway option coming in at around 5.1km and the Gt North Rd option 5.3km. The big difference though is the possible speed.
- Along the motorway corridor this could be up to the maximum speed of the vehicles (perhaps 80-100km/h)
- On Gt North Rd it would be the speed limit of 50km/h. In addition, given it would need to replace those more local services, there would also be an need to stop more often.
A quick estimation suggests that going via Gt North Rd could add five minutes of more to the travel time for those coming from further out, and that includes the motorway option stopping once or twice between Western Springs and Karangahape Rd, such as around Bond St. The exact amount of difference is uncertain at this stage as the route includes getting through the Western Springs interchange and the NZTA have tended to look poorly on anything that could potentially impact their motorway ramps. Of course, light rail is meant to have signal pre-emption but it’s unclear how that would work with a motorway interchange and frequent light rail services.
By comparison, light rail along the motorway corridor would likely be grade separated and so sail through the interchange.
Overall a five-minute saving over just 5kms is fairly significant and as much as possible we should try and keep Rapid Transit rapid.
Connection to the City
The final piece of the puzzle is to consider how the NW line would connect to the city centre – and as we pointed out recently, previous work on the busway stopped short of addressing that. There are two options for how this could be done.
- A second light rail corridor through the city.
- Share the Queen St corridor with the City Centre to Mangere line.
Let’s look at these
Second LRT corridor
This would most likely be by sending light rail down Pitt St, Vincent St and Albert St. The biggest issue with this is simply the cost of having to build another light rail corridor through the city. It would likely add $100 million or more to the cost of the project which could make it that much harder to actually happen. It would also likely leave us with two half-used LR corridors through the city.
There’s also the issue of what you’d do with the other city centre buses that would use Albert St (once the CRL works are completed). One of the reasons for building light rail in the first place is to help free up existing bus corridors because as public transport continues to grow, we’re going to need those corridors to run buses from places that won’t be served by our rail networks.
The Queen St corridor
Being able to use the Queen St corridor for both routes makes a lot of sense and ensures we get the most value of that investment. Some may say to just send LR along K Rd and then turn down Queen St but it’s quite likely that won’t be possible. The current plan for the City Centre to Mangere line is create an underpass of the K Rd ridge-line. As well as grade separating that intersection, it would be the location of the station and also help ease the grade at the southern end of Queen St.
Joining those two lines at Ian McKinnon Dr would allow both routes to seamlessly use the Queen St corridor.
Longer term we may eventually need a second city centre corridor but it be better to build it when we need it than trying to build both corridors upfront.
Overall I think the benefits of the motorway option will outweigh the Gt North Rd one and that the NZTA will come to that conclusion. There is also the added advantage that it won’t immediately put plans to upgrade Karangahape Rd and Gt North Rd into jeopardy