Sydney has nine major trunk routes feeding into the CBD, but only seven routes, including to Sydney Terminal, into or through the CBD itself. The major trunk routes are:-
- North Shore Line
- Eastern Suburbs Line
- Illawarra Line
- Airport Line
- Campbelltown/Macarthur Line (via East Hills)
- Inner West Line (Bankstown via Lidcombe)
- South Line (via Granville and Regents Park)
- Western Line (Penrith/Richmond)
- Northern Line
Each of these trunk routes feeds into the respective CBD lines as follows:-
- North Shore Line – North Shore
- Eastern Suburbs Line – Eastern Suburbs
- Illawarra Main (Eastern Suburbs Line) – Illawarra Line and South Coast Intercity (Erskineville to Central redundant)
- Illawarra Local (City Circle East) – Campbelltown/Macarthur Line via East Hills and Airport Line
- Inner West Local (City Circle West) – Parramatta and South Line via Granville
- Western Suburban (via Harbour Bridge) – Western Line and Northern Line
- Western Main (Sydney Terminal) – Western and Northern Intercity
I would be interested in your thoughts.
I've similarly summarised the problem, but I think it goes further than that.
Once a trunk route has more than 20 stations, traffic needs to be segregated by class (short haul, long haul, possible "middle" haul) otherwise you end up with absurd stopping patterns, like Kiama trains stopping at Erskinville
*A* solution to this issue - and has been fully implemented on Sector 1 - is to standardise the class of traffic into a common vehicle. Sydney long ago merged U-Bahn and S-Bahn into our hybrid double deckers, and with the G/O Sets and the impending retirement of the V sets, we are about to completely incorporate interurban traffic into the common class as well.
*If* you treat all your traffic classes as more or less the same, then you only need to worry about the trunk route geographic directions, and the problem is reduced to 9 into 7.
Similarly, if you treat all your traffic classes the same, it doesn't really matter which routes terminate at Central, just so long as 2 of the 9 do. So on that basis, I'll suggest another solution:
The Revesby-Airport line can operate independently by design - with a short single track segment on the already B-Di signalled road into Central Platform 23. (and a facing crossover just inside the airport line tunnels). Revesby-Airport-Central now an independant system. Peak frequency probably only 10min atm, but could be boosted reasonably easily, mostly just with operating practicies. 1 out of 2 excess routes removed
Other than the location of crossovers prohibits this, a similar thing could be done with the Inner West. It could terminate at Central Platform 20. This needs some actual physical work to implement, but :
2 out of 2 excess routes removed
- Crossover(s) from Inner West to Illawarra Locals *west* of Macdonaltown Jtn. (Through the stabling yard throat)
- Double Crossovers from Illawarra Local to Illawarra Mains between Erskinville and crossover/above (as @Transtopic has suggested)
- Restore old alignment of Illawarra Main Up into Platform 22 (ie Merge with the Airport Up, which will no longer be used)
- Bi-Di Signal The Illawarra Local Up (road into Central Platform 20)
- Trailing crossover on Illawarra Locals at Cleveland St
The resulting HR System is very simple, and no line has more than one junction at each end, with no flat junctions (bar Sutherland)
- Sector 1 (Unchanged)
- Sector 2: Campbelltown/Leppington - Glenfield (Jtn) - Sydenham - City Circle - Strathfield (Jtn) - Hornsby(via Epping)/Glenfield (via Liverpool)
- Sector 3: Penrith(+BM)/Richmond - Westmead (Jtn) - SHB - Nth Sydney - Hornsby(+CC)
I don't pretend that for one second that this makes a great deal of sense. But I'd suggest it makes no *less* sense than almost every other proposal around, and can be implemented with only a few new crossovers.