A new tunnel is going to be necessary, I can't argue that point. What I can ask is, is it going to be an effective use of infrastructure spending right now? Plans need to be made for a new tunnel, and it should be taken into account for future rail services and upgrades.
But this tunnel should not be a requirement for MARL, because it is not a requirement for MARL.
As for your figures. Many like to use them. These are from the 2012 PTV NDP which was written for the Terry Mulder, the Liberal Transport Minster. The issue here is they dramatically underestimated population growth. Not just in transport, but right across the state. This is from the introduction of the NDP on page 12:
This plan takes into account Melbourne’s expected growth over the coming decades. As set out in Victoria in Future, Melbourne will grow from a population of four million people to 6.5 million over the next 40 years.
Detailed transport modelling undertaken by Public Transport Victoria (PTV) shows that public transport boardings are expected to increase strongly over the next two decades, with weekday patronage more than doubling from 1.8 million to 3.8 million.
As of September 2017 Victoria is sitting at 6.3 Million People; PTV's 2019 annual report has total network boardings at 6 Million per day.
So they were a little off in the projections.
We are already starting from behind the eight ball so to speak. Let's go back to the Sunshine to City issue and break it down.
The Local Government Area of Wyndham Vale currently has a population of 288,212, forecast to 512,000 by 2040. RRL runs through Wyndham Vale, Tarneit & Manor Lakes. With the former yet to have a station. WV & Tarneit currently have a combined population of 72,104, with a projected 2040 population of 176,000. If we add in Manor Lakes that becomes 218,000
Brimbank LGA, which includes Watergardens, Keilor Plans, Albion, Sunshine & Tottenham have a projected 2040 population of 230,000, not much different from the current population.
Melton LGA taking in Melton, Cobblebank, Thornhill Park, Rockbank & Truganina have a forecast population of 485,000 an increase of 182% on todays numbers.
I don't really think 6TPH in the morning peak is going to cut the mustard for Melton, leaving little room for any growth. Which is why the government cut the airport out of MM1 last year. Watergardens currently enjoys a 7/8 minute peak frequency and most peak trains are crush load by Sunsine, thats with half the projected population of Melton. Melton will need to start with something similar to Watergardens leaving room for growth. 12TPH is quite feasible to Melton in the next 10 years. WV is not going to be much different.
Now back to those numbers one last time, let say MM1 is built as planned in 2012 and opens in 2025. Melton has 6TPH and they are at crush load in the morning peak. MM1 is at capacity as the Airport is taking up 6TPH. Where do you get those extra 2 or 3 peak hours services from? Do you steal them from the Airport or Sunbury? Or do those 300,000 people out at Melton & Rockbank need to wait until 2040 because we didn't plan ahead? What about WV, are those 200,000 people still cramming on to a couple of V/locitys? Or have we sparked RRL and Geelong and Ballarat commuters are back to crawlling behind stoppers?
The tunnel may not be a requirement of MARL, but as has been proven time and time again. If you build it on the cheap you are leaving an even bigger mess for a future government to untangle. I'd strongly argue those 52TPH I quoted will be very much needed by 2030, when MARL is expected to be complete. If built with tunnel of course.
Some fascinating big numbers there @Lockie91
You actually understated Watergardens, its more like each 6 minutes.
Pity numbers still don't support your contention for building a tunnel because of a need to double.
Some awkward numbers, with assumptions of what will/is being built.
In due course both WDV and MLT will be sparked, by provision of quad tracks.
An express pair for V/Line and an SAS pair for Metro.
V/Locity capacity = 500 per 6 car set, including standing pax.
Comeng/Seimens capacity = 1500.
HCMT capacity = 1800 (per 7 car), 2500 per 10 car
current 6tph (3 from Geelong + 3 short start).
the 3 from Geelong are 1/2 full before WDV
the 3 short start become 6 Metro tph.
3 trains from Geelong expand as required on RRL
Current capacity = 3 * 1/2 * 500 + 3 * 500 = 2,250 pax/hr
Potential capacity = 6 * 1800 = 10,800 pax/hr (or 15,000 with 10 car sets)MLT
current 4tph (short start MLT or Bacchus). Excludes express from Ballarat.
the 4 short start become 6 Metro tph.
trains from Ballarat expand as required on RRL
Current capacity = 4 * 500 = 2,000 pax/hr
Potential capacity = 6 * 1800 = 10,800 pax/hr (or 15,000 with 10 car sets)SDM (Watergardens)
current 10tph (includes start SBY). Excludes V/Line.
the 10 Metro become 12tph Metro.
Bendigo continue RRL at Albion.
Current capacity = 10*1500 = 15,000 pax/hr
Potential capacity = 12 *2500 = 30,000 pax/hr
So that's a 400% increase for Melton, and 100% increase for Watergardens.
Still haven't needed a tunnel, and the line is only assumed to be 24tph (SBY 12 + MLT 6 + Airport 6) - well short of capacity
WDV is another story.
Clearly WDV and MLT both won't fit. Could interchange which goes where , the numbers don't change.
Building a whopper tunnel, to support only 6tph is fantasy.
When you can find another 18tph in about 30 years, then that is when to plan for it. Certainly not in the middle of a state wide build that is sucking up all available resources.