One part of the City Centre Future Access Study that is particularly interesting to look through is Appendix C – the deficiency analysis. This effectively highlights in more detail what ‘the problem’ is in terms of future access to central Auckland. In particular, it highlights the difficulties arising from the future number of buses on certain parts of the network and was undertaken during the relatively early stages of developing CCFAS – so apparently doesn’t look at certain issues later dealt with in more detail, like the application of public transport crowding in the modelling.
Given the discussions of the last few days, and in particular some of the concerns about CCFAS raised by the Minister in relation to the impact of currently planned project, it’s worth noting that the deficiency analysis outlines the projects assumed to be constructed in the transport modelling runs:
The following committed transport schemes were included:
- Rail electrification;
- AMETI early stages (including SE Busway);
- Waterview connection;
- Integrated ticketing and fares;
- New bus network implementation with PTOM;
- Puhoi to Wellsford RoNS.
In addition, a number of other schemes that are currently not funded were also included, as follows:
- Additional Waitemata Harbour Crossing (in 2041 only);
- AMETI later stages;
- East-West link;
- State highway upgrades and removal of bottlenecks.
The impact of all these projects being included in the modelling is also noted:
As a result, the reference case scenarios used as the basis of this deficiency analysis included a large amount of road-based transport infrastructure investment outside the city centre. This therefore presents a ‘best case’ for the wider network in both 2021 and 2041 as there is currently no guarantee that some of the schemes listed above will be funded.
So not only are all the currently proposed/under construction motorway upgrades included in the analysis, a pile of additional motorway projects that aren’t yet funded (like AWHC and the East-West Link) are also assumed to be constructed. I do wonder whether the mess the city centre becomes in the transport modelling results might be partly because of the impact of AWHC but let’s set that issue aside for now.
There’s then a lot of discussion about the realistic capacity of bus corridors, which is critical to the issue of whether or not buses alone can handle the increased travel demands over the next 30 years. This is because the number of buses along many inner city streets increases pretty dramatically over time – even with the rationalisation of services that occurs with the introduction of the new bus network. Here are the anticipated bus volumes in 2021:
And then in 2041:
If it’s a bit difficult to read, the busiest section is on Symonds Street between Grafton Bridge and Wellesley Street – having 199 buses and hour in 2021 and 262 by 2041.The deficiency analysis then goes on to outline the problems which arise from such high volumes of buses:
…a key threshold that underpins this analysis relates to the operational capacity of a bus lane. Background research has indicated that 100 buses per hour is a reasonable threshold capacity for a single lane with no indented stops, and that the capacity can be increased to a degree with the provision of indented stops but space requirements at the stops themselves and the delays experienced by buses at junctions limits the effectiveness of increasing service capacity in this way.
…It should be noted that in the context of this analysis, such a threshold should be regarded as an upper-limit for the desirable efficient operation of a bus service rather than an absolute limit. There are many examples of bus corridors around the world operating with a combined frequency of more than 100 buses per hour, but … there is also much evidence to suggest that once this threshold is exceeded, the performance of the network in terms of delays and journey-time reliability begins to deteriorate.
Since service reliability is often identified as the most critical indicator in passengers’ perception of the quality of service, and consequently the demand for that service, there is a strong case to be made that such thresholds should be seriously considered in the planning of any bus network.
Clearly in the city centre itself, the sheer magnitude of future demand means that relying on buses alone simply cannot work due to the sheer volumes of vehicles that would need to traverse the key corridors. This is what leads to the requirement of closing off these streets to anything but buses in the Surface Bus Options looked at later in the report, but I’ll leave that further analysis for another post.
Moving further through the deficiency analysis work, it becomes clear that the problems with bus capacity exist not only on the inner city streets, but are actually much more widespread throughout Auckland. Using ‘volume to capacity’ ratios, which compare the PT demand with a realistic level of capacity supplied along that particular route, we see that demand absolutely swamps the amount of available capacity. Once again, first in 2021:
By 2041 it’s a real mess:
The ratios seem to be worked out by a comparison of future demand with the currently proposed future bus networks. If frequencies on the bus network were ramped up to provide more capacity to bring the ratios down, then the city ends up having to be hugely swamped with buses – like shown in the earlier diagrams, creating a nonsensical transport outcome. This creates the conundrum which sits at the heart of improving future access to the city centre: either the buses are enormously (and impossibly really) overcrowded or you need to run far too many buses for the city’s streets to cope with.
In fact, to meet the level of PT demand in 2021, there would need to be an average of close to 100 buses an hour on all the bus access points to the city centre:
What the deficiency analysis really highlights in my mind is how ultimately we need City Rail Link in order to save the CBD from being inundated with thousands upon thousands of buses. Of course even with CRL we will still need to run a lot of buses into town, but they will be from areas not served by rail to a greater and greater extent, while over time if we’re smart enough to build a North Shore rail link rather than a daft additional motorway crossing, there will be the opportunity to further avoid massive increases in the number of buses in the city centre over time.