Back in October last year in the AT Closed Board Meeting a item called the Northern RTN Strategic Case was mentioned, its reason for being closed “to protect information that will soon be publicly available”. Me being ever so patient, I waited for the report to be released over the coming months, once this didn’t happen I decided the LGOIMA it. Recently AT released the report in detail which can be found here.
A large portion of the report was dedicated to the importance of making sure that improvements to the RTN are aligned with the potential future Additional Waitemata Harbour Crossing (AWHC), either included as part of the crossing itself or at least so a road crossing doesn’t make difficult or even prevent necessary RTN improvements. This makes a lot of sense.
Another point to note is that this report was completed prior to the completion of ATAP, which confirmed the AWHC as not being needed as early as previously assumed and pushed it back to the third decade, although route protection should continue.
One of the great parts of the report was this graph showing what the models predict for future patronage crossing the harbour bridge every morning compared against trends over the last three and ten years. This shows the potentially huge underestimation of PT demand by official models we’ve talked about on many posts in the past.
The document confirms what we had already suspected, that the Busway was originally predicted to provide capacity well until the 2040s will now realistically be at breaking point in the 2030s, with some sections, such as in the city centre, already under strain.
Key evidence for PT demand exceeding the functional capacity of the existing Northern Busway is provided by the North Shore RTN study that compares infrastructure capacity with forecast bus volumes required to meet modelled growth in PT demand in four evaluation years: 2016, 2026, 2036 and 2046. It finds that:
- Current peak-period bus volumes exceed functional capacity already in 2016 at the City Centre end of the busway and at Constellation Station.
- Capacity problems are somewhat reduced by 2026 due to implementation of bus infrastructure improvements in the City Centre. However, Albany Station experiences capacity problems.
- By 2036 operating bus volumes that are sufficient to cater to forecast demand mean significant over-capacity operations in the City Centre and at Albany, Constellation and Akoranga Stations.
- By 2046 capacity problems exist at all major North Shore Stations and in the City Centre.
The most visible part of the busway is where it has its own dedicated infrastructure next to the motorway between Constellation and Akoranga. But it seems even that will be feeling pressure within one to two decades.
In 2016 performance issues identified include:
- Limited capacity, slow travel speeds and variable travel times for the missing segment of busway between Constellation and Albany.
- Inadequate size and capacity of Constellation Station to accommodate a large volume of bus services and passenger demand.
“However, by 2026, the joint AT/ NZTA Northern Corridor Improvements (NCI) project is anticipated to have completed the missing section of the busway, constructed a new Rosedale Busway station and provided and additional platform to Constellation Station, therefore improving these deficiencies, capacity problems are somewhat reduced by 2026 due to implementation of bus infrastructure improvements in the City Centre, however, Albany Station experiences capacity problems. However, by 2026, a significant improvement in city centre bus infrastructure has been assumed. These interventions, while still conceptual in nature and subject to funding commitments, these upgrades are still constrained by signals at intersections. As such even in 2026, soon after implementation the city centre infrastructure is likely to only just provide sufficient capacity to meet demands.
Nevertheless, by 2026, increased patronage on the busway and busway stations is likely to manifest in over capacity conditions and poor operational performance at Albany Station due to large volumes of commencing services in the AM peak which use up a lot of station capacity. Sunnynook Station which has the shortest platforms of all the busway stations will also be experiencing over capacity conditions affecting dwell times. Akoranga Station is also starting to experience congestion by this time.
By 2036, performance has degraded further at the above stations, whilst Constellation and Smales Farm are now also expected to experience over capacity conditions affecting operational performance (i.e. dwell times). all City Centre corridors and termini are likely to be under sustained pressure in peak times at between 102-108 per cent of capacity. This is likely to lead to degraded performance, with dwell times becoming more variable, increased bunching of buses and accumulation of passengers at stops congesting footways. It is in by this time period that the performance of the busway is likely to no longer be to an acceptable RTN standard.
By 2046 all of the busway stations are expected to be at or near capacity suffering from increased dwell times and greater dwell time variability affecting operational performance, virtually all parts of the City Centre used by buses would be operating at over 110 per cent of theoretical capacity, and with highly degraded and unacceptable levels of performance (slow and highly variable travel times).”
What this means is we are starting to have capacity issues now. Improvements to infrastructure such in the city centre & extending the busway to Albany as part of the Northern Corridor project will only just be able to meet demand over the next decade or so. That could of course be even sooner if the Busway continues to exceed expectations. By 2036 the system will start to resemble the congested motorway the current busway runs alongside and by 2046 the whole Busway will have broken down. So, we may need a full North Shore RTN not by 2036 but by 2026- however ATAP doesn’t have this until 2038-2048.
Nearly all the growth the growth across the Harbour Bridge is projected to be PT going from around a 1/3 of mode share today, to well over half by 2046.
At present, around one third of all trips on the Waitematā Harbour crossing are public transport trips. By the mid- 2030s public transport demand exceeds general traffic and by the mid-2040s public transport is forecast to be the dominant mode on the Waitematā Harbour crossing.
This is due in part to road capacity constraints on the Harbour Bridge, but it is also be affected by factors such as increased reliability of PT travel times at peak times due to the Northern Busway and increases in the price to park in the city centre
The report also shows that nearly all of the increased demand across the Harbour during the 30-year period is to the City Centre & City Fringe, with very low numbers increasing further south of the City Centre. There is also some increase in car demand across Upper Harbour. This is another black mark against a road based AWHC as it means a new, $3.7+ billion, six-lane vehicle crossing makes little sense, especially compared to a cheaper, RTN crossing.
We can draw two major conclusions from this report that
AWHC as we know it is a dud
This is more evidence that a road based AWHC is a sub-optimal solution for the area, with nearly all growth in demand across the harbour being on PT, and towards the City Centre & Fringe. Trying to serve the demand towards the City Centre & Fringe, where road capacity is already stretched and not realistically able to be increased, with an expensive road crossing makes zero sense.
We should re-evaluate the option of a cheaper, transit only crossing
While the report mentions that by 2036 Northern Busway Services will deteriorate to the point the service is no longer RTN standard, realistically by 2026 a new PT crossing may be needed even if needed CBD Bus Infrastructure is brought forward. That’s because if growth continues like it has recently, are we so certain the busway will be able to cope between 2026-2036.
There is also no reason the road/rail components need to be combined, for one thing, the road alignment is not likely to be the best alignment for rail. With capacity constrained much sooner than the road crossing is now said to be needed, we should reassess building a transit only crossing first. ATAP estimated a tunneled light rail line connecting from Wynyard Quarter to at least Takapuna at $1,868 million with an extension to Grand Drive Orewa at another $868 million. So that’s $2.7 billion for light rail from Orewa to the City, compared to $3,7 billion for the road tunnels alone. We should also reconsider making this particular crossing a bridge. As well as being much cheaper than tunneling, it could allow walking and cycling from the start. A road crossing could then be build as a second (or Third) stage when it is needed in the future
The last point I would like to make on the report is that once again PT solutions reactive, it is not until they have broken down from over-utilisation that better PT is considered. We need to change to a more proactive view where we see PT investment as being an agent for transformative city improvement, instead of waiting till the last possible minute.