This idea seems simple on the surface, but it will have system-wide consequences on deeper examination. Are these system-wide consequences positive or negative? After extensive thought, my conclusion is that an extension to Liverpool (using a direct route via Bankstown Airport) will be a game-changer for Sydney Metro, and make it arguably the most important line by far in all of Sydney's rail network.
This is all without any further branching of Sydney Metro, an idea I've over time shifted to become less in favour of. In fact, branching would be highly undesirable and a single unbranched line will provide supreme benefits of simplicity, high frequency and reliability whilst being a good match for the increased capacity requirements of serving Liverpool.
The key to why the Liverpool extension has such system-wide implications is what happens to the Cumberland line. Given it's continuity with the Liverpool extension of Sydney Metro, it makes sense to incorporate at least part of the Cumberland line into Sydney Metro as well. This would bring Sydney Metro connections to Parramatta (a key centre that currently does not have Sydney Metro access). The result is shown in the rail diagram below (which also contains other rail plan ideas, but of main relevance to Sydney Metro is the Sector T3 orange curve).
As seen above, incorporating the Cumberland line into Sydney Metro will finally allow rationalisation of the complex interactions of the Cumberland line with Sector T2's Innerwest & South line. What are these interactions? There is a tension between whether the stations from Liverpool to Merrylands should have single seat (ie: interchange free) access to Parramatta CBD or to Sydney CBD. As a result, rail planners have tried to do both by having Cumberland line and Sector T2 share tracks up to Merrylands, where the former branches west (via Harris Park) and the latter to the east (via Granville). This has resulted in compromised frequency and increased complexity for both lines. The lack of frequency is a major problem, as with wait times of 15-30 minutes, the Cumberland line is an unattractive option compared to just using interchange at Granville. Likewise, the inner west line only offers frequency of 4-6 trains per hour at Newtown, which is unsatisfactory.
By connecting the Cumberland line to Sydney Metro, the Liverpool to Merrylands stations will get their CBD access via Bankstown, instead of via Granville. As Sydney Metro will have higher frequencies (15-30 trains per hour instead of 8), faster acceleration and also reduced dwell times compared to current trains, travel times to Sydney CBD via Bankstown will be competitive with the current Sector T2 (Innerwest & South) Granville route. The need for Sector T2 (light green line in diagram above) to service these stations drops away and as a result Sydney Metro will have exclusive use of the Liverpool to Merrylands tracks and offer high frequency rapid services to both Parramatta and Sydney CBD. At the same time, Sector T2 becomes a lot simpler and has a lot of capacity freed up to offer a high frequency service for the remaining inner west stations. Sector T2 is still more branched than ideal, but one of these branches is distally located and very short (two stations) and is therefore more of a spur than a full branch.
Finally, this also solves "problems" for Sector T3 (Sydney Metro) itself. If terminated at Bankstown, it's substantial potential 30 train per hour capacity is underutilised, and there have been calls for additional southern branches to Sydney Metro. With the extension to Liverpool and onto Cumberland line tracks, Sydney Metro can avoid the need to add more branches. Branches are undesirable due to increased complexity, as well as causing crowding at CBD stations whilst people wait for the right train. Better to have a simple linear system that is highly reliable and very frequent... this is what makes metros like Hong Kong MTR so successful.
So the extension to Liverpool will be a win for Sydney Metro, a win for the inner west and a win for better Parramatta connectivity, a win for Liverpool and a win for Bankstown airport. Let's hope this idea from Liverpool council gets taken up.
No comments:
Post a Comment