You are clearly familiar with many of the operating benefits of single deck trains, such as higher track capacity and faster journey times, judging from media reporting. These benefits, as well as significant construction advantages, would prima facie favour single deck trains for a second Sydney Harbour rail crossing and CBD link, subject to there being a high acceptance of standing by passengers.
However, the situation for the NWRL is much less clear. The higher capacity benefit would not be relevant due to the limit of 20 trains per hour that has been engineered into the Epping Chatswood Rail Link and a lower acceptance of standing, the long average station spacing (3 km) that makes the impact of faster journey times less significant, and the NWRL being initially aligned for double deck trains. Further, there are some longer term peak period opportunities that only double deck trains can provide:
The situation will be significantly different before the second crossing is completed, due to constrained peak period capacity between Chatswood and the Sydney CBD. Helpful measures include diverting some of the outer Northern Line patronage via Strathfield and ensuring a more even loading distribution between trains to minimise overcrowding and consequent dwell time blowouts. The argument that initially running a frequent Chatswood-NWRL shuttle (during peak periods) would help with this loading distribution appears reasonable.
Making this initial shuttle single deck also provides an opportunity to thoroughly prove a new set of designs and technologies before deployment to other parts of the Sydney rail network. However, converting the NWRL to double deck operation as part of this deployment would make the overall network more consistent with the principle that Tier 1 services are for “busy inner areas” (it’s a stretch to describe the North West, and future extensions, as such), make possible the opportunities mentioned above and also re-enable off peak Northern Line trains to run to at least Chatswood. It would also leave more cross harbour metro capacity available for future development, such as to Brookvale, and remove the ironic situation of double deck buses, but not trains, being able to serve the North West.
In summary, there are four broad areas in which double deck trains on the NWRL would have an advantage to offset the acknowledged benefits of single deck trains in the longer term. These include avoiding (at least partially) Northern Line impacts, adhering to the three tier principles and taking advantage of the additional opportunities mentioned above, as well as a more general concern about single deck suitability and network flexibility. Thus introducing single deck trains on the NWRL involves a balance of sometimes conflicting benefits.
My reading of Sydney’s Rail Future, on which the Transport Master Plan is based, shows no evidence of this balance being considered. The conclusion that a chosen three tier solution performs best does not logically mean that the best use of Tier 1 services is being made. Other inner area lines are more deserving while, as already noted, the NWRL has several long term disadvantages. Each area of disadvantage has been the subject of media publicity and presumably correspondence to you.
May I suggest Minister that a much more open dialogue needs to take place between the various operator and user interests to demonstrate that an appropriate balance is being achieved, as the current reliance on media bites to support apparently entrenched positions is far from satisfactory. My own view is that short term and long term (i.e. before and after a second crossing) issues need to be differentiated as part of this dialogue.
Each single deck train is estimated to have around 500 seats, judging from the seating and door arrangements in the video material that has been released. Accordingly, the maximum number of seats between the North West and the Sydney CBD will be around 10,000 per hour, given the limit of 20 trains per hour on the ECRL. Fewer seats would be available from the North West if some services from the ECRL to Parramatta were also to be provided, given this limit.
Breaking the Nexus
As noted in the letter, the nexus can be broken by converting the all stations to Gordon service to single deck. Although less convenient, it is still relatively straightforward.
Additional tracks would be needed between Chatswood and Gordon to separate single deck and double deck services, and new single deck underground platforms would be needed at Chatswood to preserve the current turn back arrangements. As under the nexus, four tracks between Chatswood and the Sydney CBD would be needed, however the connectivity would be different. Single deck trains would use the existing route through Wollstonecraft and Waverton before entering a tunnel to Mount Street and then under the harbour, while the new tunnel from St Leonards via Crows Nest would be built for double deck trains and connect with the existing North Sydney platforms.
Running frequent single deck trains all stations to Gordon would allow the number of North Shore double deck services to be reduced to eight per hour at peak times; four from the Central Coast and four from Berowra/Hornsby. This opens the way for 12 trains per hour to run from the ECRL into the Sydney CBD, making the total 20 trains per hour. This number should be easier to reliably achieve after the second rail crossing is in place as much of the congestion-causing interchange traffic would be drawn away from the existing CBD stations.
12 double deck trains with almost 900 seats means a little over 10,000 seats per hour between the North West and the Sydney CBD can be provided. While broadly similar to the single deck figure, it would also be possible to run eight additional trains per hour on the ECRL as far as Chatswood. These could be services from Parramatta and/or the North West, with the latter providing more seats between the North West and Chatswood. Neither would reduce the maximum number of seats per hour between the North West and the Sydney CBD.
There is also a need for better consistency when comparing single deck and double deck trains. On the same basis of counting all seats and standing at 4/m², the total capacity numbers are about 1,300 and 1,700 respectively. However, a more realistic number for double deck trains is around 1,300 (2/m² standing) to avoid excessive dwell time blowouts and allow 24 trains per hour under ideal conditions of wide platforms, modern signalling and good approach alignments. Thus a valid track capacity comparison between single deck at 30 trains per hour and double deck would be around 15,000 seated/39,000 total verses 21,500 seated/31,000 total, rather than the 24,000 total that can be achieved with double deck trains under existing conditions.