In the announcement of the next steps for light rail last week, Transport Minister Michael Wood confirmed that part of the investigation over the coming six months is not just about the City Centre to Mangere route but that whatever is chosen will also form the basis for future extensions to the Northwest and the North Shore – as also envisioned in ATAP. In this post I want to focus on that shore connection.
Late last year Waka Kotahi completed the latest of many studies into Additional Waitemata Harbour Connections. At the time the main area of interest was the high-level programme that will be implemented over the next 30 years, as well as some of the key findings about the analysis of road options.
As shown below, the long-term programme involves three key steps: enhancing the busway, providing a rapid transit connection and then making some form of road enhancement.
Some of the findings around what the ‘road enhancement’ should be were quite interesting – highlighting the extremely high cost of a road tunnel, and the quite marginal impact any form of extra road capacity would have on travel times:
Setting aside the small matter of whether we want to spend $10 billion on inducing more traffic into the city and creating hardly any improvement in travel times, some of the work done in the business case on the second component of the programme – the rapid transit connection – warrants further analysis and a bit of questioning.
The business case looked at different rapid transit options in two phases – first through a broad assessment of options like:
- Just enhancing the busway through station upgrades and better bus priority in the city, and doing no more
- Turning the Northern Busway into some form of “Advanced Busway”, presumably using larger, tram-like buses.
- Upgrading the busway to light-rail, and building a light-rail spur to Takapuna
- Heavy rail on a completely different alignment to the busway (presumably in a really long tunnel)
- Converting the busway to light-rail and then extending it in a tunnel right through the isthmus to Onehunga before linking up with the Onehunga-Airport light-rail system.
- Building an ‘on-street’ light-rail system that follows key arterial roads (Taharoto, Forrest Hill and East Coast roads) from Takapuna up to Long Bay
As per the earlier diagram, the busway enhancement was taken forward as a key part of the programme, but was considered insufficient alone to meet forecast future public transport demand. Therefore, at some point in the next 20 years, an additional rapid transit connection was seen as necessary. In the graph below it seems like the increase in bus volumes from 78 per hour to 110 per hour, almost one every 30 seconds, are enabled by the busway enhancement – but growing demand means at some point in the late 2020s through to mid-2030s demand exceeds capacity of the system. When this happens you can expect to see overcrowded platforms and buses getting in each other’s way, leading to slower and less reliable trips. A higher capacity crossing – some form of rail – would therefore be needed.
The business case’s second stage of analysis looked at a shorter list of options – each in addition to the busway enhancements.
A few things caught my attention about these options:
- The ‘red’ option is pretty similar to what we’ve outlined in the past in the ‘Congestion Free Network‘ and other posts on here but instead of having a branch from Akoranga to Takapuna, the line serves Takapuna directly, like we talked about here. This is good in the sense of linking Takapuna with areas north and south more efficiently, but probably adds a huge amount of cost in the form of a long tunnel under Takapuna and between Takapuna and Smales Farm.
- The ‘green’ heavy rail option is oddly different to the heavy rail option assessed in the earlier phase. This one terminates at Smales Farm, which means most of the North Shore would continue to be served by buses and heavy rail would only have two stations (Takapuna and Smales Farm).
- The ‘blue’ light-rail option is essentially the same as the red option south of Smales Farm, but weirdly between Smales Farm and Albany it goes onto an elevated structure directly above the busway. Goodness knows why you would ever go to the trouble of building a massive light-rail viaduct right on top of a busway and serve no new areas than what already have rapid transit access from the busway.
The different options (including variations of the ‘blue’ option above that ended at Smales Farm or extended all the way to Albany) were modelled to compare forecast use in around 30 years’ time:
What’s noticeable from these results is that only the ‘busway to LRT’ option (the red option) sees rail meeting the bulk of public transport demand from the North Shore, with the busway playing a supporting role (given it would only exist as a busway between Smales Farm and the city). This seems sensible – in most cities around the world the higher capacity mode meets most of the demand and lower capacity modes play a supporting role. The other options seem like they would really struggle to stack up – with the massive new rail projects only serving a very small share of demand.
One potential issue with the ‘red option’ is that its capacity only just meets 2048 forecast demand levels. Unlike the other options, where the rail crossing’s capacity is fully ‘in addition’ to the busway, in this option converting the busway to light-rail means some bus capacity is lost. However, the other options seem like they have a huge amount of unused rail capacity – which I suspect means in their current form would really struggle to pass any ‘value for money’ test.
In terms whether the line should be light-rail, light-metro or heavy rail, or whether the harbour crossing should be a bridge or a tunnel, the business case briefly discusses these issue before summarising some of the key findings:
While there’s some useful stuff in here, I find myself with just as many questions as I started off with. Things like:
- Should we really put much effort into upgrading the busway if we’re serious about a future rail crossing in a decade or so that will vastly reduce busway demands?
- Why did the business case spend so much time looking at frankly bizarre options like putting a light-rail line right above an existing busway?
- What’s really limiting capacity on a single light-rail line that serves the North Shore? If it’s the city centre (which I’m guessing is the case) then couldn’t that issue be fixed another way, by having two routes through the city or eventually tunnelling?
- Is it really worth all the tunnelling to provide direct access to Takapuna from the north and the south, compared to a branch line from Akoranga like in the Congestion Free Network?
- Would ‘light metro’ provide enough extra capacity to make the ‘red option’ work in the long-term?
- At least some of the push for a duplicate corridor north of Smales Farm seems to be coming from concern about the disruption to the busway during construction. While not ideal, surely our planners and engineers are capable of coming up with ways of working around that, like they did when the harbour bridge was damaged. A couple of years of disruption is nothing on outcomes that will shape the city for a century or more.
I can’t help but get a nasty feeling that the rapid transit options looked at in this work are all far too expensive – relying on lengthy tunnels that either won’t ever be affordable or worse are simply a trick to get a road tunnel back on the agenda. In the past it was a case of building a motorway and maybe some PT/Active mode improvements will be tacked on but with the harbour crossing at least, it feels the opposite, building a rail line in order to tack on an even more expensive road.
With the new Light Rail Establishment Unit kicking off, I hope their work looks at more realistic and affordable options – such as involving a new PT and active mode bridge across the harbour and a single rapid transit corridor that meets the bulk of demand, supplemented by buses where it makes sense to do so.