For the case of Macquarie Park, particularly unhelpful is the huge deviation to the north (as far as Lindfield) taken by the Epping to Chatswood link (ECRL), just prior to the junction with Chatswood. This has been panned by numerous observers as a shambolic debacle. However, as we shall see later, this deviation may prove to be a "saviour" in cutting down the Hornsby to CBD journey time from over 40 minutes to 25 minutes or less.
Post commissioning of Sydney Metro Northwest in 2019, the two main routes from Hornsby to Wynyard will be either via the North Shore line ("orbital" route) or via Strathfield ("grid" route). Let's compare these two routes:
A) "Grid route": Hornsby to Wynyard via Strathfield:
- distance: 32km (approximate/"smoothed")
- stops: as few as 7 stops (Epping, Eastwood, Strathfield, Redfern, Central, Town Hall, Wynyard)
- travel time: 41 minutes
B) "Orbital route": Hornbsy to Wynyard via Gordon:
- distance: 22km (approximate/"smoothed")
- stops: 17 stations (typical service pattern)
- travel time: 42 minutes
(Wynyard and not Central is the key stop in Sydney CBD for the purposes of this comparison, as it's the station with the highest quantum of office based land use and hence time sensitive commuting populations).
Note the "grid" route is quicker than the "orbital", even though the latter is 10km shorter. This is because the "grid" route has fewer stops, which in turn is a reflection of the quadruplication of tracks on significant portions of the northern line and the sextuplication of tracks between Strathfield and Central. The multitude of tracks allows service differentiation, with some tracks used for express trains stopping at fewer stops. In comparison, the North Shore line has only a single track pair and has limited ability to offer express services especially when it needs to operate at 20 trains per hour capacity. Another speed limitation to note is that both the "grid" and the current "orbital" route are slowed down by some quite sharp turns and steep inclines, north of Epping and south of St Leonards respectively.
Ironically, the much criticised deviation of the ECRL offers intriguing possibilities. In particular, the ECRL will be temporarily shut down for the large part of a year prior to commissioning of Sydney Metro Northwest in 2019. What if during this time, a tunnel stub was added near Lindfield to the ECRL tunnel. This should be simple to do by bring in a road header from the Chatswood end of the tunnel.
Then also plan for a 3km extension of these stubs to Gordon (alongside existing railway corridor south Gordon, or even continuing in tunnel). At Gordon join up the newly created tunnel stubs to the existing north shore rail line (adding an extra platform at edge of the commuter parking immediately east of Gordon station, so that the total of 4 platforms at Gordon will allow cross platform interchange between the two lines).
Finally, the remaining piece of the "Hornsby to CBD in 7 stops" puzzle is to create an "express tunnel" from Chatswood to the CBD. This is almost exactly what Sydney Metro "City" aims to do, except they are thinking of putting in stations at St Leonards and North Sydney/Victoria Cross before finally reaching the first CBD station at Barangaroo. However, the latter two stations overlap with existing station catchments in the lower north shore area of Sydney, which is an area that is already extremely well connected by public transit and already has very high public transit use.
These two stations are also potentially complex and expensive to construct (Victoria Cross will be especially deep and will cause challenging grades for the tunnel going under Sydney Harbour). So why not scrap these two stations, save significant cost in the process and allowing the proceeds to be used to for infrastructure enhancements elsewhere. (Sydney Metro users can still easily access St Leonards and North Sydney stations by using the cross platform transfer capability at Chatswood.)
So putting these all together, we now have a 22km orbital route from Hornsby to Barangaroo, which will be express south of Gordon all the way into the CBD - a total of only seven stations versus the existing 17 stations. Furthermore, the new express tunnel will be only very gently curved, and have very gentle grades making it very fast and efficient. There is also an operational consideration involved in that Sydney Metro will use modern signalling systems and rolling stock that will be incompatible with the existing double deck system. So initially the express tunnel might terminate at Gordon, until the signalling between Hornsby and Gordon can be modernised, allowing Sydney Metro to extend as far as Hornsby.
However, a major advantage of an express tunnel bypassing North Sydney is that it may offer the possibility of a "double deck" compatible cross harbour tunnel. This is because the gradient of the descent from Chatswood to Sydney Harbour will be much shallower, and suitable for single and double deck rolling stock. If additional openings in the future Chatswood platform screen doors are added, and if double deck rolling stock can be retrofitted to work with both the old and new signalling systems then it may be possible for these trains to still use the new express tunnel.
The Lindfield stubs also keep open the possibility of a Northern Beaches branch of Sydney Metro going to Forestville. Of course, whether it be either a Hornsby branch or a Northern beaches branch, there are disadvantages to branching. In particular, capacity and frequency gets halved with one branching (versus no branching). However, by putting the branch at the Lindfield curve, at least the main trunk route between Chatswood and the CBD gets the full 30 trains per hour frequency, whereas other proposals to add stubs at North Sydney will have the branching come in much closer to the CBD. If there is to be branching, best keep the branches as far out in the periphery as possible.
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