A few weeks ago we learnt that Waka Kotahi NZTA were due to release a new business case for a harbour crossing and that it would recommend first enhancing the Northern Busway and then looking at a public transport crossing ahead of any new road crossing. The business case is now available and there’s quite a bit of interesting information in it.
Firstly, let’s just look at some of the numbers and issues.
They say the North Shore currently home to about 337,000 people and that by 2048 that is expected to increase to 497,000, a 160,000 or 48% increase. Of that, around 103,000 people are expected to expected in
sprawl greenfield growth north of Albany. Of the remaining growth, most of it is expected in three areas, Albany, Takapuna and Northcote.
It is also expected that job growth on the Shore will not match population growth and mean there will be a lot more travel demand in the future with the city centre and fringe being key destinations for work and education trips. On the Shore, Takapuna and Smales Farm are expected to become the most significant employment zone while industrial areas like Wairau and Rosedale are not expected to see much growth.
The report says the Harbour Bridge “is the most travelled route in New Zealand“, moving around 235,000 people a day – 171,000 vehicles a day (205k people at an assumed occupancy of 1.2) and 30,000 PT trips. However SH1 just south of the city between Gillies Ave and Khyber Pass carries over 201k vehicles a day or about 240k people.
The graphs below show traffic flows and capacity of the bridge throughout the day now and forecast in 2048 – although models are frequently wrong and the southbound one seems to have an error as surely the AM peak should have nearly 9k capacity like northbound in the PM peak.
Despite modelling things in 2048, the report notes that:
Due to the wider network capacity constraints on the road network, public transport needs to accommodate all peak direction, peak time additional cross-harbour travel in the future. This scale of demand growth means the Northern Busway (including its stations and key city centre bus routes) will become overwhelmed in the future, with the additional buses needed to meet demand placing pressure on stations and city centre streets, ultimately resulting in longer and less reliable trips.
This trend has already been happening for the city centre as highlighted in this graph – though this is not just from the shore but all city centre trips
The scale of the growth means that even with busway enhancements enabling 110 double-decker buses an hour, the buswa will hit it’s effective AM peak capacity in the early 2030’s.
The report also talks up the importance of the bridge to moving goods and highlights the growth of Heavy Commercial Vehicles, particularly in recent years. What the authors seem to have not realised though, and something we’ve confirmed with Waka Kotahi in the past, is that double-decker buses count as HCV’s and they were first introduced to the network in 2013 so it’s quite possible a big chunk of the increase is actually the result of the growth in PT.
There’s much more detail and background information in the report but let’s move on to the more exciting stuff.
As mentioned at the start, the report confirms the priority is to first enhance the busway, then to add another rapid transit connection and lastly to add road crossing. Let’s look at these
At an estimated $500-600 million it’s easily the cheapest of the options but also the recommendation that stands out the most to me. That’s because the original 6km of busway and about 2.3km of southbound bus lane along with the five original stations cost just under $300 million while the currently under construction 4km busway extension and the Rosedale station will likely have a similar cost. This shows that the envisioned enhancements are much more substantial than I had previously imagined.
Looking at the options we can see why. It would essentially build a busway spur to Takapuna, fully extend the busway to the base of the bridge including an Onewa Station and include improvements in the city centre. These improvements are expected to increase the capacity of the existing busway by about 30%. Of note, the do minimum changes include a 50% increase in bus frequency all across the North Shore.
There is also a separate version of the busway enhancements map that doesn’t include the Takapuna Spur or Onewa station so it’s not clear if those will still be in the programme.
They also investigated a separate ‘Advanced Busway’ which would have taken things a step further and seen high-capacity articulated buses capable of carrying 170 people and included full bus priority on the bridge.
The initial part of the report looks at a range of PT options, including the enhanced and advanced busways mentioned above. Three of these are shown below
The third one is interesting as it lines up with options we’ve talked about before and would enable a full light metro line from Albany to the Airport. This could of course be staged over time. What’s also notable is that while it about doubles the cost of Option 4, it’s still cheaper than the heavy rail option which would only be just for the connection from the city to Albany.
However, the report says that even if the busway was converted to light rail, about a 40% increase on the enhancements above to about 14,000 people an hour, it still wouldn’t have enough long-term capacity. As such, it seems they’re looking at this new crossing as potentially being independent of the busway and meaning we could end up with two separate rapid transit lines parallel to each other, which would mean lots of capacity but doesn’t really expand the reach of the RTN network other than possibly a station at Takapuna.
Something doesn’t quite add up here though as some light metro style options overseas are capable of moving 25k-30k people an hour suggesting the authors are not modelling things correctly, perhaps assuming services run less frequent than is possible.
The report there has an additional rapid transit assessment and below are some of the questions about it they’re trying to answer:
This extra study looks at three options, effectively light rail, light metro and heavy rail. The main difference to the initial options seems to be that it would initially only go from Smales farm to the city until it is decided how to get it further north, but would include a diversion to Takapuna.
It doesn’t actually state a preference for any mode and notes that there “is little difference in attractiveness between light and heavy rail“. The decision on which mode to use is really going to depend on the wider plans for rapid transit in Auckland. Part of the next phase of work is look more closely at both the mode and timing questions. The summary suggests this crossing could cost $6-7 billion however the report also notes that a bridge option could be only $2-3 billion and have lower operational costs. All options would have greater costs to get the connection north of Smales Farm.
The engineers can’t bear to not include a road crossing so it’s still in the plans. They’ve looked at three options with costs of $1 billion, $2 billion and $10 billion.
Options 2 and 3 are what they’re looking at more closely but at least at this stage and despite only adding two lanes, the $2 billion option seems to perform fairly well compared to the $10 billion option. It also appears to be considered more feasible and has a better benefit to cost ratio – though both are terrible at 0.3 and 0.2 respectively.
There is also a quick analysis of the benefits and challenges of separate or combined crossings. The short answer is they say “separate tunnels are preferred at this time“.
Overall, given how long this has been worked on, I’m surprised by how high-level it all is. The report is useful but seems to ask more questions than it answers. Hopefully we will learn more from the next steps – as shown below: