But isolating a railway and forcing all passengers to change trains isn't a particularly 'friendly' way to deal with the problem.
Saying 'we will only run to Chatswood and make you change trains so the new line can always run on time' is the cheap way of solving the problem.
Although running the NWL as a separate operation isn't the only one - they are also proposing running several branch lines as shuttles and terminating other trains at Sydney Terminal.
That's just more of the same thinking - bugger the passenger/customer, do what ever it takes to get Service Level statistics to look good.
This IS a good way of dealing with the problem.
Just taking as an isolated view, lets looks at what is proposed initially for the NWRL and what is rumored to happen for the Richmond line (run through to Campbelltown).
Scenario 1 - the old way:
With the status quo situation, you have 20 trains scheduled to run through the city from the west in the peak hour but trains often run late as you have trains from different stopping patterns on 3 branches all merging into a common track pair over the bridge (Richmond, Emu Plains, Blacktown stoppers, Lower Northern line).
From the north you have 18 trains scheduled to run from mostly 2 branches, which would become 3 with the NWRL (which would get 4tph at a stretch).
In the CBD in the evening you have congested platforms as people wait on the platform up to 15 minutes for their train to show up.
Complicated = unreliable
Differing stopping patterns = crowded platforms
Unreliable = people building time into their travel plans for inevitable delays (like I mentioned before - there is no use having a 45 minute to work 4 days a week when it takes 60 minutes on 1 day a week - you then need to allocate 60 minutes travel time every day).
Scenario 2 - simplified:
In this situation the NWRL runs to Chatswood as a shuttle at a headway of 5 minutes. Richmond runs to Campbelltown at a headway of somewhere between 6 - 10 minutes. Northern line runs to Sydney Terminal at a headway of 6 - 10 minutes. The Western line runs Emu Plains all to Blacktown, Seven Hills (for cross platform interchange with Richmond line), Parramatta, Lidcombe, Strathfield, Redfern, Central, all to North Shore at a headway of 3 minutes (stopping pattern irrelevant as long as it is consistent and fast).
Single stopping pattern per track pair means that there are no delays at junctions and travel time becomes certain. People change to the express service where needed to get to the CBD.
CBD platform congestion is reduced as every train from the platform will go to the same destination so there is no need to hang around on the platform waiting (people are missing that this is probably one of the biggest drivers of this plan).
You can segregate train types to improve travel speeds by allowing each train type to perform to it's maximum capability - e.g. Tangaras on Richmond - Campbelltown, Waratahs on Western line which could accelerate faster and run 160kph while running express.
Increased time changing offset by reduced uncertainty of travel time and faster speeds on individual sections (45 minute trip could become two 20 minute trips with a 5 minute interchange time but actually achieve that 5 days a week - even if it becomes 50 minutes, it is still below the 60 minutes that needed to be allocated previously due to uncertainty).
There is also the travel time saving of the increased frequency - someone could finish work and head to Town Hall and have to wait average 7.5 minutes for a NWRL train under the first scenario, or wait an average of 1.5 minutes in the second, followed by an average wait on 2.5 minutes at Chatswood, for an end-to-end saving time of 3.5 minutes without even taking into account the fact that the NWRL trains are supposed to run 10% faster than DD stock would have.
Ultimately the 3 minute headway on the Western/North Shore line (which looks like it will become 2.5 minute headway with ATO) will be exhausted and this is when the second harbor crossing will be required. Of all the options for incorporating the NWRL into the network I have seen/heard so far (with the exception of the logical option of building the second harbour crossing before the NWRL as should be happening) the current government plan is one of the best.
Great post. This should be required reading for anyone who wants to participate in this or other similar threads.