What you don't appreciate is that I'm suggesting new segregated metro lines be restricted to the higher density inner and middle ring suburbs, which would have to be underground and would be cheaper to build and operate than the existing heavy rail.  Because of their relatively short distance, seating is not a priority.

How about light rail? This could be segregated light rail. While metro-style rail does work best in high density areas like you mention, you still seem to be advocating the metro-suburban devide, and nowhere else in the world is setting out to do that.

Rodd Staples proposed a metro in the dense parts and that proposal was wildly unpopular.

However, for longer distance services to the outer suburbs, then I support the expansion of the existing heavy rail network, which will require further track amplification through the inner city suburbs, mostly underground, such as an express tunnel from Granville to the CBD which I have mentioned earlier.  This could support an express rail link from Badgerys Creek Airport to the CBD via Parramatta in addition to an express link to the CBD via the East Hills Line.  An express tunnel on the Western Line corridor could potentially be extended via the previously proposed City Relief Line to interchange with the metro at Barangaroo.  An underground extension of the East Hills Line from Wolli Creek Junction to the CBD may also be required in the longer term for south west services.  This mirrors what is happening with London's Crossrail.  Many of the major cities in Europe have U-Bahns and S-Bahns, including Paris with the metro and RER.  It's horses for courses.  I don't agree with the North West Rail Link being metro operation BTW, but that's history now.

I don't fully get this but most of the major cities in Europe and Asia were heavily developed before the railways. The metros in these cities mostly run in the old parts, the ones heavily developed before the railways, and in most major cities that have both metro and suburban rail, it was metro that came first. This was the case, for example, in London, Paris and Berlin.

There is still scope to improve reliability and speed of the current network with a goal of reducing the operating patterns to preferably a single pattern on selected lines, cutting the fat from the current timetable and introducing ATO with upgraded signalling.  Dispensing with guards and introducing driver only operation would also greatly reduce costs.  The latest and planned rolling stock is capable of much higher speeds and acceleration/deceleration characteristics.

What operating patterns? What fat from the timetable?

Also, dispensing with guards also seems worrying. It cound create or worsen some problems with what happens on board trains. Sydney trains have a very high capacity per train.

I've used the Paris RER, I think the line that uses the two car trains is the one closest to where we always stay and the local station is quite curvy, like Sydney. Three door trains cannot be used on stations that have excessive curvature track because the middle door could be too far away from the platform. If I recall the station we used the platform was even low set because of the curve.

I didn't know that the R.E.R also had some curved platforms.

The tram will never be returned, no one builds trams on roads anymore apart from short sections and crossing roads. Bradfield didn't reserve a ROW for the line, just visioned one would be needed as none exists, the future line will need to be a Metro, building the line as a DD line would be retrograd and costly with no benefit to anyone. At least the Metro can be built cheaper and longterm lower operating costs.

Building the line to the loading gauge that Dr. Bradfield wanted would mean more comfortable trains with more seats.

The reason 100 years ago they couldn't build tunnels for DD stock or large profile stock was because it was done with pick and shovel efficiently. The TBM's technology is certainly more practical and capable, but still incurs an elevated cost over smaller profile stock. Longer trains are cheaper to cater for than wider and taller trains.

Any idea how much the added cost is elevated? Percentage wise? In hard currency? Longer trains need longer platforms, and tenches for stations are the biggest part of the tunneling cost.

Sydney's abilty to build through corridors for the DD under the city is tribute to the short distance and timing connecting existing lines. Paris wasn't trying to do this, it was trying to build a inner suburban railway network in a growing, very old existing narrow street city. Even trams were of limited effectiveness. The city is also built on ground that is easy to dig by hand. Sydney is built on Sandstone, not so hard to dig by hand and doesn't need extensive shoring up as you dig hence easier to allow for larger profile tunnel.

First of all, at least some, if not most of the C.B.D tunnels were cut and covered. Also, it was done before double decker trains and but it turned out to be large enough for them.

So back to the start again, Sydney is now where Paris was 100+ years ago. Growth will only be under ground corridors and most of this will be Metro type technology.  To try and do otherwise would incur building underground tunnels to connect the parts of the existing network that are not congested that are 20-40km long, commonsense says this isn't going to happen is it. Its not what Bradfield, Rod Staples did or didn't do, its where we are today that matters. Numerous cities build new Metro lines completely technology islanded from existing to grab the latest technology, no need to mix lines as this is inherently poor design for growth and upgrades as Sydney is finding out. Segregation of the Bankstown line to the Metro will enable this line to be moderised more rapidly in the future than the legacy network as backward compatibility is less of an issue.

Yes, inner Sydney has indeed run out of surface options, and the old parts of cities like Paris never had them. But Sydney already has heavy rail, including surface rail in its busiest parts, those older cities did not before they had metro.

And in London, Paris and Berlin, the focus now is on extending (electric) suburban rail into and through the centres. Nowhere else in the world is anyone setting out to recreate the metro-suburban divide. History shows why that divide exists.

You are too busy telling us why the RER is so wonderful, yet you haven't even ridden it or bothered to ask about it


Bradfield lived in a different era, when the suburban network was operated more like a regional rail network. Now its about packing them in. Train loading gauge also doesn't define seat comfort. Passengers don't need seats for journey's less than 30min, 33% of rail users currently don't sit in peak and around similar on buses.

Viaduct construction of the BRisbane Airport line in 1998 was around $212m for 15km of track, most single and only two stations. Viaduct is not practical on terrain with too much gradient which the Victoria Road line will suffer from plus the medium strip is not wide enough.

Note: You have the skyrail project in Melbourne as a comparison.

In Sydney, no! dug as a tunnel.

Sorry you are wrong on last. Most cities including London and Paris are extending their inner and outer communter train lines into the city using what works for them and the technology available. If its greenfield, often they just grab the latest with few concerns of interchangable.

The so called Metro-Suburban divide is a figment of your imagination only. even cities with relatively new commuter rail systems build the next line often with non-compatible technology because they know something you don't.

Back to the OT
There is no one definition of "Metro", often its referenced as Paris due to the original source of the name, but even Paris does not have a single definition with its roughly 14 lines have a number of different designs and technologies, again using the best available at the time or upgraded. Even Paris is a clasic definition of why its better not to have a large scale 100% interchangeable network, as they have automated some existing lines and will do more and in some cases converted the rail to a combined rail and rubber tyre. Again having the line separated means this is relatively quick and cheap.

In comparison for Sydney everything must be backwards compatible and no large scale platform changes are possible. A classic example that keeps coming up is conversion to 25kVAC. Such a project would take decades and cause frequent issues in trying to do so. Longterm I see that Sydney will separate its "sectors" physically. Trains and crews will not share the same tracks or be interchangable.

There is still scope to improve reliability and speed of the current network with a goal of reducing the operating patterns to preferably a single pattern on selected lines, cutting the fat from the current timetable and introducing ATO with upgraded signalling.  Dispensing with guards and introducing driver only operation would also greatly reduce costs.  The latest and planned rolling stock is capable of much higher speeds and acceleration/deceleration characteristics.

What operating patterns? What fat from the timetable?

Also, dispensing with guards also seems worrying. It cound create or worsen some problems with what happens on board trains. Sydney trains have a very high capacity per train.

Question is what are the guards actually benefiting or needed?
They cannot see the whole train, especially at busy and/or curved stations and more so if they are not tall and the move to fixed 8 car sets won't make things better.

If its just train boarding at busy stations then better to redeploy them along the platforms of stations where they are in constant use. Rather than riding train in the outer part of the network where things are much quieter.

For me, they cannot be removed just now, but could be or reduced over time. Again having a large single technology network, actually makes it difficult. Some lines may never see guards removed, others potentially. In Qld the GC to Airport line is the closest, also the line most easily expanded to 9 cars and/or 3 door sets if you factor in the future CRR and upgrading of some existing stations on Beenleigh line, but not the current inner city platforms.

Bradfield lived in a different era, when the suburban network was operated more like a regional rail network. Now its about packing them in. Train loading gauge also doesn't define seat comfort. Passengers don't need seats for journey's less than 30min, 33% of rail users currently don't sit in peak and around similar on buses.

Larger loading gauge means trains can be larger at maximum, and there can be more floor space and more seating.

Most cities including London and Paris are extending their inner and outer communter train lines into the city using what works for them and the technology available. If its greenfield, often they just grab the latest with few concerns of interchangable.

First of all, what does "wrong on last" mean? I did say they are extending their suburban rail into and through the old parts of the cities.

The so called Metro-Suburban divide is a figment of your imagination only. even cities with relatively new commuter rail systems build the next line often with non-compatible technology because they know something you don't.

The metro suburban divide is where one network has smaller trains  with stops every kilometre or so and another network in the same city has larger trains stopping further apart.
These are cases where the metro is largely confined to the old part of the city, and came before suburban rail, or at least before it was electrified.
For example, there is the London Tube North of the Thames, which was already built up by the time of the coming of the railways. Ironically, it was this part of England that gave the world railways.

And in Paris, the metro is largely confined to the peripherique, with mainy the R.E.R serving the newer urban development in Ile de France.

In comparison for Sydney everything must be backwards compatible and no large scale platform changes are possible. A classic example that keeps coming up is conversion to 25kVAC. Such a project would take decades and cause frequent issues in trying to do so. Longterm I see that Sydney will separate its "sectors" physically. Trains and crews will not share the same tracks or be interchangable.

There is plenty of dual-voltage rolling stock elsewhere in the world. If every double decker train in New South Wales had at least a space for a transformer, conversion work could have started once the single deckers were withdrawn.

Bradfield lived in a different era, when the suburban network was operated more like a regional rail network. Now its about packing them in. Train loading gauge also doesn't define seat comfort. Passengers don't need seats for journey's less than 30min, 33% of rail users currently don't sit in peak and around similar on buses.

Larger loading gauge means trains can be larger at maximum, and there can be more floor space and more seating.

Most cities including London and Paris are extending their inner and outer communter train lines into the city using what works for them and the technology available. If its greenfield, often they just grab the latest with few concerns of interchangable.

First of all, what does "wrong on last" mean? I did say they are extending their suburban rail into and through the old parts of the cities.

The so called Metro-Suburban divide is a figment of your imagination only. even cities with relatively new commuter rail systems build the next line often with non-compatible technology because they know something you don't.

The metro suburban divide is where one network has smaller trains  with stops every kilometre or so and another network in the same city has larger trains stopping further apart.
These are cases where the metro is largely confined to the old part of the city, and came before suburban rail, or at least before it was electrified.
For example, there is the London Tube North of the Thames, which was already built up by the time of the coming of the railways. Ironically, it was this part of England that gave the world railways.

And in Paris, the metro is largely confined to the peripherique, with mainy the R.E.R serving the newer urban development in Ile de France.

In comparison for Sydney everything must be backwards compatible and no large scale platform changes are possible. A classic example that keeps coming up is conversion to 25kVAC. Such a project would take decades and cause frequent issues in trying to do so. Longterm I see that Sydney will separate its "sectors" physically. Trains and crews will not share the same tracks or be interchangable.

There is plenty of dual-voltage rolling stock elsewhere in the world. If every double decker train in New South Wales had at least a space for a transformer, conversion work could have started once the single deckers were withdrawn.

Like anything there is a cost:benefit ratio to designing trains.

Any city will use the most suitable technology to extend a line or build a new one based on their individual circumstances. The reason the older type Metro systems were very limited in length because of their high underground cost of construction at some point becomes nonviable due to the reducing population density as you move away from the city. Again the cost:benefit ratio. Less people equals less congestion on roads and other modes of transport, less need for a subway.

Other issue is that in particular PAris in the past station spacing is very close as close as 500m on some lines making longer transit times very slow, so extension of these lines is not practical.


The metro suburban divide is where one network has smaller trains  with stops every kilometre or so and another network in the same city has larger trains stopping further apart.

This is really an ideology of your own making. It applies to a hand full of cities at best.

These are cases where the metro is largely confined to the old part of the city, and came before suburban rail, or at least before it was electrified.

Again applies to a handful of cities and many of these have moved on.

For example, there is the London Tube North of the Thames, which was already built up by the time of the coming of the railways. Ironically, it was this part of England that gave the world railways.


Meanwhile the original tube lines have progressively been extended further afield and the new CRR is different approach again.

Any city will use the most suitable technology to extend a line or build a new one based on their individual circumstances. The reason the older type Metro systems were very limited in length because of their high underground cost of construction at some point becomes nonviable due to the reducing population density as you move away from the city. Again the cost:benefit ratio. Less people equals less congestion on roads and other modes of transport, less need for a subway.

The reason is because the heavily developed areas of the time were limited in size. They did not need a metro within the territory of steam trains.

Other issue is that in particular PAris in the past station spacing is very close as close as 500m on some lines making longer transit times very slow, so extension of these lines is not practical.

Paris metro rolling stock is designed for short haul stop-start runs. Note that there has only been one completely new Paris metro line in the entire postwar period. This one is designed to be a filler line, and it is a deep tube line, going under the river, older metro lines and the R.E.R. This adds to the cost and inconveninece of building stations.

The metro-suburban divide is not an ideaology, some cities really do have smaller trains stopping every kilometre or so in one part, and have larger trains stopping further apart on a separate network.
This is different from having multiple metro lines separate from each other with different technologies, and this itself either only remains for historical reasons or is part of a transition.

Meanwhile the original tube lines have progressively been extended further afield and the new CRR is different approach again.

Look at a map of the tube and you'll see they are still confined to the north side of the Thames. The Jubilee line is also the only completely new line in the entire postwar period, all the others were built before the first world war.

@Myrtone Correction the Jubilee line isnt the only new line built post war. The Victoria qas also built post war, in 1968. My father had worked on the tunnelling.  Secondly the Victoria line was the only entirely new line. The first stage of thw Jubilee line was .mostly the takeover of the Stanmore branch of the Bakerloo line. The only new section was betwèen Baker Street and Charing Cross.

Michael

Most aren't building traditional metros anymore.  They are building more suburban based rail.  No real need for the traditional metro anymore and they are more expensive. (Stations are the most expensive part of underground rail)

The Paris RER lines move far more people an hour than metro lines, and in more comfort

Most aren't building traditional metros anymore.  They are building more suburban based rail.  No real need for the traditional metro anymore and they are more expensive. (Stations are the most expensive part of underground rail)

The Paris RER lines move far more people an hour than metro lines, and in more comfort

Really?

Name one city building large scale expanding underground with RER type technology? RER is not a inner suburban commuter network, its suburban to outer suburb to regional rail network.

The standard densely populated train technology for lines that are predominately underground looks like this picture below (or similar) made with TBM's on straight platform stations, increasingly with platform doors. Typically two rows of longitude seats, occasionally fixed facing forward or back. Designed for standing capacity and fast on/off via lots of doors which prevent high level of seating capacity, not sitting.

More and more are automated and have no drivers cab, just passenger cab with a nice view forward. Stations spaced 750m to 1500m apart depending on location but rarely closely spaced for long distances.

The RER loading capacity is similar to that of Sydney per car, just their cars are longer due to 3 car door trains (mostly) to enable much faster dwell times than Sydney because unlikely Sydney the RER services numerous number of of capacity stations. However Sydney is catching up.



What is correct is no one is building these anymore due to their poor loading capacity driven by tunnels built by hand. With stations 500m apart.

Name one city building large scale expanding underground with RER type technology? RER is not a inner suburban commuter network, its suburban to outer suburb to regional rail network.

Name one city that developed with the railways that is has since built or is building any large scale network that is mostly underground, or an older city where a substatial portion of such a network is within the newer parts of the city that developed with surface railways.

The standard densely populated train technology for lines that are predominately underground looks like this picture below (or similar) made with TBM's on straight platform stations, increasingly with platform doors. Typically two rows of longitude seats, occasionally fixed facing forward or back. Designed for standing capacity and fast on/off via lots of doors which prevent high level of seating capacity, not sitting.

And there are mostly elevated metros that have similar technology. Some metro style networks are mostly underground, others are mostly elevated.
All regional and suburban rail networks are mostly surface or elevated, some have large enough loading gauges for double decker trains, the rest have loading gauges large enough only for single deckers.

@RTT_Rules I would have thought Crossrail is similar to RER (albeit with single-deck trains)?

@RTT_Rules I would have thought Crossrail is similar to RER (albeit with single-deck trains)?

Yes, so why are they doing SD?

The argument floated by Mytone is that typical Metro style trains, which by the way is extremely broad but lets describe them as SD, 3-4 door sets with limited seating in favour of standing is not being built in favor of Sydney DD or RER type trains.

My argument is that Metro style trains as mentioned above previously is the standard for new inner city and often suburban networks. DD RER style or Sydney is expensive and limited to existing legacy networks which are typically outer suburban / inner regional such as Paris. Yes they run through the city centre, but only on lines with high traffic volumes where the higher costs for short routes in tunnels is a cost they are willing to absorb because it works.

However today if you are building a new inner suburban commuter line, especially one underground or even if elevated its Metro style, usually automated and as boring as F__k in appearance. Running usually A-B clockwork timetables with minimal if any branch connections or mixing with other lines.

Example of city building new lines to the above standard ie automated Metro mostly underground or on Viaduct which usually incorporated underground sections in the older parts of the city
Vancouver
Dubai
Sydney Metro
Singapore NE line
Delhi
etc etc
Plenty more in EU and asia for those willing to be bothered to look up.

Now, go and try and find someone doing the same with DD technology? Save your time, you won't and the reason is obvious, its alot cheaper per body moved to build a Metro and few govt's are these days going to invest in larger project costs so most pax sit for a 30min ride, as it is now deemed acceptable to stand for this long whether the community likes it or not and this exists now in Sydney with many stations and even bus stops known that at certain times of the day, you will stand for your journey.

RER most lines are 3 door trains where the stations are mostly straight and even with their extra car length of 24m, they hold the same number as Sydney seated, but have a higher standing ratio. The 3 door design making dwell times short compared to Sydney. There is however 2 door RER trains on tracks where stations have too much curvature and they suffer like Sydney in dwell times and I believe these lines do not run 2min headways, rather 3min (personal observation).

Historically Sydney had but 2-3 slow boarding stations at certain times. Sydney, Town Hall and Wynyard with a few other minor ones. Times are changing, low density housing areas are now high rise with more coming and many of these people forgoing car ownership or usage. Chastwood station on a Saturday afternoon reminds me of peak hour in the 80's.  

Meanwhile the automated Metro's lines are pushing 90sec and typically doing the same route km as above faster if applied to the same stations.

The London Overground isn't one of the the ones that can convert to double decker. And what do you mean by "not being built in favor of Sydney DD or RER type trains".

My argument is that Metro style trains as mentioned above previously is the standard for new inner city and often suburban networks. DD RER style or Sydney is expensive and limited to existing legacy networks which are typically outer suburban / inner regional such as Paris. Yes they run through the city centre, but only on lines with high traffic volumes where the higher costs for short routes in tunnels is a cost they are willing to absorb because it works.

Double deckers like on the Sydney suburban and R.E.R are on the increase on all the busiest heavy rail networks that can convert to double decker.

However today if you are building a new inner suburban commuter line, especially one underground or even if elevated its Metro style, usually automated and as boring as F__k in appearance. Running usually A-B clockwork timetables with minimal if any branch connections or mixing with other lines.

Let's take a closer look at the cities that have these.

Example of city building new lines to the above standard ie automated Metro mostly underground or on Viaduct which usually incorporated underground sections in the older parts of the city
Vancouver
Dubai
Sydney Metro
Singapore NE line
Delhi
etc etc
Plenty more in EU and asia for those willing to be bothered to look up.

Dubai is (I'm told) no normal city and apparently quite spread out as a strip with pockets of development with vacant land in the long gap between stations. The underground section in the old city apparently does have close station spacing. Also, these metro type systems don't co-exist with established and electrified suburban rail networks.
Such networks don't exist in Singapore, Dubai or Delhi. Sydney metro is back-to-front with single decker, 3-4 door sets with limited seating in favour of standing but with stations and suburban spacings running at suburban distances.

The London Crossrail can't run DD trains because of the limited loading gauge of the existing Overground network with which it connects, not that they would necessarily choose to if it was possible.  So it's SD.  Crossrail is essentially a century late in linking up separate surface suburban lines through the centre of London, similar to Bradfield's plan for the Sydney Underground.  While Crossrail is automated through central London, it still has a driver for the existing outer sections where it will share some tracks with other Overground services.  It may have metro style rolling stock, but that doesn't make it a "metro" in the accepted sense of the terminology.  It is still basically a "suburban" system similar to Paris's RER and Sydney's rail network.

Unlike London, all of Sydney's suburban lines now traverse the CBD, so there is virtually no need for any further cross city connections from the outer suburbs.  However, that doesn't mean to say that future track amplification wouldn't be required on existing lines to meet the increased patronage demand for future suburban extensions, such as a link to Badgerys Creek Airport.  The only CBD extensions I would make for the existing network is for an express tunnel from Granville to Barangaroo to augment the Western Line and diversion of the Airport Line from the City Circle to a new terminus (St James perhaps).  All other new inner city lines should be part of a segregated automated metro system.

The London Overground isn't one of the the ones that can convert to double decker. And what do you mean by "not being built in favor of Sydney DD or RER type trains".

My argument is that Metro style trains as mentioned above previously is the standard for new inner city and often suburban networks. DD RER style or Sydney is expensive and limited to existing legacy networks which are typically outer suburban / inner regional such as Paris. Yes they run through the city centre, but only on lines with high traffic volumes where the higher costs for short routes in tunnels is a cost they are willing to absorb because it works.

Double deckers like on the Sydney suburban and R.E.R are on the increase on all the busiest heavy rail networks that can convert to double decker.

However today if you are building a new inner suburban commuter line, especially one underground or even if elevated its Metro style, usually automated and as boring as F__k in appearance. Running usually A-B clockwork timetables with minimal if any branch connections or mixing with other lines.

Let's take a closer look at the cities that have these.

Example of city building new lines to the above standard ie automated Metro mostly underground or on Viaduct which usually incorporated underground sections in the older parts of the city
Vancouver
Dubai
Sydney Metro
Singapore NE line
Delhi
etc etc
Plenty more in EU and asia for those willing to be bothered to look up.

Dubai is (I'm told) no normal city and apparently quite spread out as a strip with pockets of development with vacant land in the long gap between stations. The underground section in the old city apparently does have close station spacing. Also, these metro type systems don't co-exist with established and electrified suburban rail networks.
Such networks don't exist in Singapore, Dubai or Delhi. Sydney metro is back-to-front with single decker, 3-4 door sets with limited seating in favour of standing but with stations and suburban spacings running at suburban distances.

New Inner suburban commuter lines are being rolled as SD at 10 x of more the rate of the small incremental and very limited DD trackage expansion. Usually as new Outer Suburban connections to the city over inner suburban.

It would be best to not speak on authority on places you haven't been too, include the RER, Dubai, Singapore etc. Your perception/information of Dubai and its Metro are very wrong.

I think you'll find Delhi does have an existing HR network as does Vancouver and Singapore had regional trains decades before the MRT. And in the case of Dubai, with a clean slate look what they choose to build??? As did Singapore MRT and Vancover Skytrain and  Delhi.

Station spacing is irrelevant.

The London Crossrail can't run DD trains because of the limited loading gauge of the existing Overground network with which it connects, not that they would necessarily choose to if it was possible.  So it's SD.  Crossrail is essentially a century late in linking up separate surface suburban lines through the centre of London, similar to Bradfield's plan for the Sydney Underground.  While Crossrail is automated through central London, it still has a driver for the existing outer sections where it will share some tracks with other Overground services.  It may have metro style rolling stock, but that doesn't make it a "metro" in the accepted sense of the terminology.  It is still basically a "suburban" system similar to Paris's RER and Sydney's rail network.

Unlike London, all of Sydney's suburban lines now traverse the CBD, so there is virtually no need for any further cross city connections from the outer suburbs.  However, that doesn't mean to say that future track amplification wouldn't be required on existing lines to meet the increased patronage demand for future suburban extensions, such as a link to Badgerys Creek Airport.  The only CBD extensions I would make for the existing network is for an express tunnel from Granville to Barangaroo to augment the Western Line and diversion of the Airport Line from the City Circle to a new terminus (St James perhaps).  All other new inner city lines should be part of a segregated automated metro system.

The term "Metro" is so misused its not funny. There is no 1 size suits all.
Could be
- automated/manual/semi-automated,
- rail powered/rail-tyre powered,
- 3rd rail, O/H, 4th rail, side rail,
- AC/DC, Diesel
- Low voltage, higher voltage
- Low density seating/high density seating

I think the best generic definition is "inner suburban/city rail system".

The option of terminating the Airport train at St James isn't a bad one, would need about 1.5km of tunneling and a new station at Pitt Street.

The option of terminating the Airport train at St James isn't a bad one, would need about 1.5km of tunneling and a new station at Pitt Street.

Just to expand on that.  My initial thoughts were to divert the Airport Line at Central to the unused U/G platforms 26 & 27 and continue on to St James.  Being on the upper level of the station box, it wouldn't be too steep a dive from the existing tunnel portal under Prince Alfred Park.  However, regrettably, part of platforms 26 & 27 are to be used for plant and services for the new metro, so that option is effectively cut off.  It's a shame they didn't have more foresight and left the option open for future use of the platforms for a new rail link.

The advantage of extending the Airport Line to St James and removing it from the City Circle is that it takes the line further into the CBD where it can terminate using the unused centre platforms.  There's already a turnback in place.  This would allow for cross platform interchange to and from the City Circle, or it could even continue around the City Circle in the off-peak.

Unlike London, all of Sydney's suburban lines now traverse the CBD, so there is virtually no need for any further cross city connections from the outer suburbs.  However, that doesn't mean to say that future track amplification wouldn't be required on existing lines to meet the increased patronage demand for future suburban extensions, such as a link to Badgerys Creek Airport.  The only CBD extensions I would make for the existing network is for an express tunnel from Granville to Barangaroo to augment the Western Line and diversion of the Airport Line from the City Circle to a new terminus (St James perhaps).  All other new inner city lines should be part of a segregated automated metro system.

Metro was developed for cities like London, these didn't have mainline railways traversing the historic core, and London still doesn't. Sydney differs from many other global cities in a number of ways:
*Late development with surface rail serving the busiest parts of the city right from the beginning. The suburban railways were electrified before there was a need for underground railways, first through the C.B.D and later out to the Eastern suburbs. This early electification meant that the existing network could be extended underground instead a separate third-rail electric network being started. This was due to the intervention of Dr. Bradfield.
*Generous loading gauge which meant larger trains with more seats and a larger luggage size limit. Again, Dr. Bradfield fought for this before double decker trains.
The Hong Kong MTR luggage size limit is such that a student got into trouble simply for carrying his cello on a train. Larger train size allows means that trains could be fitted with bike racks so that bicycles can be carried onto trains meaning that many commuters can cycle to and from stations instead of walking, a great advantage with wide station spacing. A double decker train with bicycle racks may still have higher capacity than a "cattle class" single decker without them.

Unlike London, all of Sydney's suburban lines now traverse the CBD, so there is virtually no need for any further cross city connections from the outer suburbs.  However, that doesn't mean to say that future track amplification wouldn't be required on existing lines to meet the increased patronage demand for future suburban extensions, such as a link to Badgerys Creek Airport.  The only CBD extensions I would make for the existing network is for an express tunnel from Granville to Barangaroo to augment the Western Line and diversion of the Airport Line from the City Circle to a new terminus (St James perhaps).  All other new inner city lines should be part of a segregated automated metro system.

Metro was developed for cities like London, these didn't have mainline railways traversing the historic core, and London still doesn't. Sydney differs from many other global cities in a number of ways:
*Late development with surface rail serving the busiest parts of the city right from the beginning. The suburban railways were electrified before there was a need for underground railways, first through the C.B.D and later out to the Eastern suburbs. This early electification meant that the existing network could be extended underground instead a separate third-rail electric network being started. This was due to the intervention of Dr. Bradfield.
*Generous loading gauge which meant larger trains with more seats and a larger luggage size limit. Again, Dr. Bradfield fought for this before double decker trains.
The Hong Kong MTR luggage size limit is such that a student got into trouble simply for carrying his cello on a train. Larger train size allows means that trains could be fitted with bike racks so that bicycles can be carried onto trains mean that many commuters can cycle to and from stations instead of walking, a great advantage with wide station spacing. A double decker train with bicycle racks may still have higher capacity than a "cattle class" single decker without them.

I think you will find numerous commuter networks all round the world have limitations on what size objects you can take on the train, especially in peak or peak flow as is (or was) the case in Qld where bikes are prohibited in peak flow. Even the RER prohibits bikes on its trains in peak with numerous other restrictions out of peak. Crowded trains regardless of their size is not the place for bikes or large items. Dubai bans large or multiple suitcases (not sure on actual rule) on its trains despite have airport stations. The reason for these restrictions on busy commuter lines should be plainly obvious and nothing to do with the dimensional size of the train.

Bike racks reduce seating spaces and hence why few networks provide them except in very limited locations which are typical bike/ PT cultures. Most of the DD RER stock would have very few places to put bike racks.

No one is building train and boring tunnels based on the need to carry a few bikes on the trains, so this whole argument pointless.

Metro was developed for cities like London, these didn't have mainline railways traversing the historic core, and London still doesn't. Sydney differs from many other global cities in a number of ways:
*Late development with surface rail serving the busiest parts of the city right from the beginning. The suburban railways were electrified before there was a need for underground railways, first through the C.B.D and later out to the Eastern suburbs. This early electification meant that the existing network could be extended underground instead a separate third-rail electric network being started. This was due to the intervention of Dr. Bradfield.
*Generous loading gauge which meant larger trains with more seats and a larger luggage size limit. Again, Dr. Bradfield fought for this before double decker trains.
The Hong Kong MTR luggage size limit is such that a student got into trouble simply for carrying his cello on a train. Larger train size allows means that trains could be fitted with bike racks so that bicycles can be carried onto trains mean that many commuters can cycle to and from stations instead of walking, a great advantage with wide station spacing. A double decker train with bicycle racks may still have higher capacity than a "cattle class" single decker without them.

Myrtone, you're missing the whole point of this discussion.  Forget about DD v SD.  That's no the issue.  It's about the appropriate form of rail system to service inner city and outer suburban markets.  

Sydney, unlike some European cities, already has a suburban rail system servicing the CBD core, not just the fringe, but it doesn't have a high capacity inner network similar to the so called "metro" systems. Had Bradfield's original proposals for an extensive network of inner city lines serving the Eastern Suburbs, South Eastern Suburbs and Inner West, been realised, then we wouldn't be having this discussion.  Now we're playing catch-up with the latest proposals for metro expansion in the inner city.  I agree with RTT on this strategy.  

Having said that, I don't support the North West Metro as it should have been built as part of the existing suburban network, which was the original intent.  It remains to be seen how well it is received by commuters once it's up and running.  I also don't agree with converting the Bankstown Line to metro. It's a waste and also compromises direct express services to Liverpool.  Now that the North West Metro is a fait accompli, I would have preferred it to be extended from Central to Parramatta as the West Metro Line.  Capacity on the City Circle could still be freed up by diverting the Airport Line to a new city terminus as suggested above.  To service the Bays Precinct, I would build a new metro line along the Victoria Road corridor, say to Epping via Ryde and Eastwood, linking with a previously proposed South East Metro across the CBD.  It could also potentially be extended from Epping to Parramatta.

I think you will find numerous commuter networks all round the world have limitations on what size objects you can take on the train, especially in peak or peak flow as is (or was) the case in Qld where bikes are prohibited in peak flow. Even the RER prohibits bikes on its trains in peak with numerous other restrictions out of peak. Crowded trains regardless of their size is not the place for bikes or large items. Dubai bans large or multiple suitcases (not sure on actual rule) on its trains despite have airport stations. The reason for these restrictions on busy commuter lines should be plainly obvious and nothing to do with the dimensional size of the train.

I didn't say that there weren't limitations on luggage size, I said the limit can be larger with more floor space per passenger.
Double decker trains allow larger luggage size than equivalent single deckers carrying the same number of passengers.

Compare the luggage limit in Dubai with that on larger trains elsewhere that carry fewer passengers per square metre.

Bike racks reduce seating spaces and hence why few networks provide them except in very limited locations which are typical bike/ PT cultures. Most of the DD RER stock would have very few places to put bike racks.

A double decker with bike racks near the entrance doors will still have more seating spaces than an equivalent single decker. The fact is that allowing bicycles on trains, combined with wide station spacing, would actually encourage more bicycle use.

As noted before, double deckers trains are increasingly deployed on all suburban and regional rail networks where they will fit. And one reason for doing so is greater passenger comfort.

One place bike racks can go on double deckers is right near the doors, where the floor level is between that of the decks.

And if even a double decker train doesn't have enough room bicycle accomodation, at least during peak periods, then another solution is to make trains longer, at least if platforms are long enough or could be made longer. 12 car DD; Lots of room for bike racks in the vestibules and still plenty of seating space.

Sydney, unlike some European cities, already has a suburban rail system servicing the CBD core, not just the fringe, but it doesn't have a high capacity inner network similar to the so called "metro" systems. Had Bradfield's original proposals for an extensive network of inner city lines serving the Eastern Suburbs, South Eastern Suburbs and Inner West, been realised, then we wouldn't be having this discussion.  Now we're playing catch-up with the latest proposals for metro expansion in the inner city.

Suburban rail serving the C.B.D core almost since surface rail was electrified, combined with surface rail serving the busiest parts of the city before then, has meant there has never been a need for metro style rail. The original Bradfield proposal was for those inner city lines to be part of the same network as all other lines. He did not propose a separate network with smaller trains where most peak period passengers stand.

Having said that, I don't support the North West Metro as it should have been built as part of the existing suburban network, which was the original intent.  It remains to be seen how well it is received by commuters once it's up and running.  I also don't agree with converting the Bankstown Line to metro. It's a waste and also compromises direct express services to Liverpool.  Now that the North West Metro is a fait accompli, I would have preferred it to be extended from Central to Parramatta as the West Metro Line.  Capacity on the City Circle could still be freed up by diverting the Airport Line to a new city terminus as suggested above.  To service the Bays Precinct, I would build a new metro line along the Victoria Road corridor, say to Epping via Ryde and Eastwood, linking with a previously proposed South East Metro across the CBD.  It could also potentially be extended from Epping to Parramatta.

The North West Rail "Link" is certainly not in metro territory. Metro rolling stock, such as Alstom's Metropolis, is designed for short haul stop-start runs but will be running suburban distances on the Northwest rail "link" with station spacing like the existing Sydney suburban.

Sydney suburban has a large number of express services. Trains from the outer suburbs run express or nearly so in the inner suburbs. On my trips to Sydney, I don't recall any all stations trains.

Dr. Bradfield apparently had a line along Victoria Road which was planned as part of his suburban rail network, with the same saze trains as all other lines.

His intervention has enabled two tier services on almost every line. Less frequent stopping and less dwelling on dwell time.

But one mistake that was definitely made is not building the city railway according to the original plan. For example, building Town Hall station with just one track and platform face per running line instead of two. Another is not making all platforms long enough for twelve car trains.

Mytone,
Obviously you don't understand govt and private railway project management and planning.

For one, they don't build DD trains to give more pax, crush loading is based on floor space and seating capacity. Remove the seats and you have more standing capacity and more capacity on the train. Dubai like many cities running train frequencies based on loading factor and the train technology is irrelevant.

If you have been on a RER you will notice there is almost no mid level seating.

While most govts tolerate bikes on their trains, one bike takes up the space of two pax and can add significantly two dwell times to get on and off crowded trains and platforms as well as significant safety issues, hence why restrictions are in place in many cities.

Now you are contradicting yourself, you are promoting longer platforms.

The NW Metro is being built to typical modern design standards used on commuter railways. ie stations placed based on volume of people due to the very high cost of building and operating stations especially underground stations. ie you need X many people per hour to make the station economically viable. Same approach has been used in both Singapore and Dubai when opening stations on new lines were certain stations were left closed for in some cases years until the surrounding population demands caught up. Also minimising the number of stations on a line saves significant travel time and more attractive.

Sydney has a number of lines all stations to the city (from outer suburban) with no express running due to traffic density. There will be more in the future as the population increases unless extra capacity is built.  The use of using one pair of tracks to run both express and local is a hang up of the past. As in most cases the corridor width is full thus forcing more complex and costly issues such as tunnelling as is happening. The issue being that these corridors are not short, rather 10's of km long thus making these project multi billion dollar projects and adding even 0.5m extra width to the tunnel can add hundreds of millions of dollars to a project.

What Bradfield did or didn't intent is completely irrelevant and honestly I doubt any of us need these never ending regurgitated history lessons (often incorrect) of yours. The govt of today has to work with the infrastructure of today and with the cash flows of today.   Its called the real world where real money from taxpayers is used to build stuff and they face real limitations in project funding.

For the most part I don't give a crap for DD vs SD. Its what I see that is being done by real govts around the world
You say DD is expanding, I only see DD commuter networks expanding in a very limited number of locations and not being used for inner suburban expansion and upgrades. For every new DD carriage that is being built, there is probably at least one train set of SD fully Automated that is being built. China built how many new lines in last 20 years, how many are ?

Finally Mytone
The biggest issue for Sydney Rail transport is not DD or SD as you like to point out its the cost. Its expensive to build, has a history of projects especially tunnel based projects that run over time and significantly over budget, ESR being case in point. A project of such a cluster it took +25 years before the NSW govt would look at a tunnel project again, which was again truncated.  Additionally once built the network is high cost to run. Despite Peak being heavily uterlised with most lines running at above capacity loading and capacity train frequency and very popular and growing off-peak usage, the cost recovery is less than 25c-30c in the dollar. Therefore for rail based transport to expand in Sydney and keep pace with the city growth, it needs to find cheaper ways to build railway tunnels with lower operating costs and SD Automated trains of lengths of 160m is the way forward.

Myrtone, you're missing the whole point of this discussion.  Forget about DD v SD.  That's no the issue.  It's about the appropriate form of rail system to service inner city and outer suburban markets.  

Sydney, unlike some European cities, already has a suburban rail system servicing the CBD core, not just the fringe, but it doesn't have a high capacity inner network similar to the so called "metro" systems. Had Bradfield's original proposals for an extensive network of inner city lines serving the Eastern Suburbs, South Eastern Suburbs and Inner West, been realised, then we wouldn't be having this discussion.  Now we're playing catch-up with the latest proposals for metro expansion in the inner city.  I agree with RTT on this strategy.  

Having said that, I don't support the North West Metro as it should have been built as part of the existing suburban network, which was the original intent.  It remains to be seen how well it is received by commuters once it's up and running.  I also don't agree with converting the Bankstown Line to metro. It's a waste and also compromises direct express services to Liverpool.  Now that the North West Metro is a fait accompli, I would have preferred it to be extended from Central to Parramatta as the West Metro Line.  Capacity on the City Circle could still be freed up by diverting the Airport Line to a new city terminus as suggested above.  To service the Bays Precinct, I would build a new metro line along the Victoria Road corridor, say to Epping via Ryde and Eastwood, linking with a previously proposed South East Metro across the CBD.  It could also potentially be extended from Epping to Parramatta.

The alt to the Metro approach was to build the same NW line as DD spec. However the govt and most of us know a 2nd pair of tracks from Chatswood to Redfern was required to make the NW line viable. The line would have cattered for both the NW and Hornsby via Epping traffic, perhaps replacing Nth Shore as Berowa trains to justify increase in frequency and take some work of the North Shore line. You don't want entanglement of North Shore and trains from Epping sharing tracks from Chatswood. The only part I would have changed is an additional station at St Leonards.

On the south side the New Inner West Bays Line (new line going up Vic Road to Eastwood or West Ryde) and existing Bankstown lines could have been connected to the new tunnel thus allowing for both capacity increase on these lines and balancing the traffic volumes. This would become mostly an operational island (apart from section to Liverpool) which is aligned with clearways perhaps called T10.

Building a separate new line on south side however would have added +$10B to the project and added a few years to full completion but not stopped early truncated operation. The Airport line St James terminus option would give some relief on the city loop tunnels and you still need Pitt Street station to make this viable and minimise changing trains for city bound/sourced flyers. (Personal experience twice to the city in last 3 years). This project would needed to be done in conjunction with the Chatwoods to Redfern tunnel project.  

However it doesn't solve the govts problem
1) Higher and unreliable underground construction costs that other countries
2) Higher operating cost technology
3) Inflexible timetable to match live load capacity needs
4) A very large single platform network that is difficult and costly to upgrade progressively. Everything has to be backwards compatible.

The Metro extension to Liverpool for me has to happen. I know the govt has gone quiet on it, but it has to happen to make the Bankstown Line conversion practical, just like extension to Richmond line.

The Airport to St James Options I still think is an excellent idea, the loss of the unused platforms does nto prevent this from happening as I think only the Airport trains use Platforms 22/23, just need an additional viaduct parallel to existing lines then into a new tunnel, new Pitt Street Station and St James terminus using a shunt neck to enable cross platform changes for City Circle to Circular Quay and Wynyard.

For one, they don't build DD trains to give more pax, crush loading is based on floor space and seating capacity. Remove the seats and you have more standing capacity and more capacity on the train. Dubai like many cities running train frequencies based on loading factor and the train technology is irrelevant.

I don't get this distinction. Train technology does affect capacity.

While most govts tolerate bikes on their trains, one bike takes up the space of two pax and can add significantly two dwell times to get on and off crowded trains and platforms as well as significant safety issues, hence why restrictions are in place in many cities.

Let me tell you something; Bicycles take up less space than wheelchairs. And bicycles can be stored vertically and take up even less space.
You suggested that even double deckers might not be large enough to carry bicycles as well as passengers, so making the platforms longer and using longer trains would leave enough space for them.

No comment on the standards to which the metro is being built.

Sydney has a number of lines all stations to the city (from outer suburban) with no express running due to traffic density. There will be more in the future as the population increases unless extra capacity is built.  The use of using one pair of tracks to run both express and local is a hang up of the past. As in most cases the corridor width is full thus forcing more complex and costly issues such as tunnelling as is happening. The issue being that these corridors are not short, rather 10's of km long thus making these project multi billion dollar projects and adding even 0.5m extra width to the tunnel can add hundreds of millions of dollars to a project.

Maybe on the North Shore line but there's lots of Quaruple track on the south side so express trains wouldn't need to share the same pair of tracks as all stations trains.

You say DD is expanding, I only see DD commuter networks expanding in a very limited number of locations and not being used for inner suburban expansion and upgrades. For every new DD carriage that is being built, there is probably at least one train set of SD fully Automated that is being built. China built how many new lines in last 20 years, how many are ?

Double deckers are indeed being depolyed on all the busiest regional and suburban rail networks where they will fit. Look at Belgian National Railways, Luxembourg state railways, Russia's Aeroexpress, the German state of Brandenburg (which surrounds Berlin), and Zuerich's S-bahn, and Switzerland's other suburban rail network, in Bern.
And get this, the Luxembourg, Brandenburg, Zuerich and Bern orders are all for the same train model - from Stadler. The Russian order is for a Soviet gauge variant.
If a single decker from a European supplier built for an Australian legacy system only needs to be lightly customised, why should a double decker from the same supplier be more so.

No comment on the rest.

There is more to designing a commuter railway line and its capacity than a specific train design. Why not use the Indian Profile, its 6 seats across with arm rests?

Let me tell you something, catering for bikes is optional, catering for wheel chairs is a legal requirement and community expectation.

Nothing to do with size of train meaning there is space for bikes, its loading capacity. of the trains and even Sydney's high density loading would have no room on many services for bikes or if you tried you'd pi$$ alot of people off doing so and add to the dwell time. Fortunately Sydney has yet to have enough problems yet that will require the govt to ban them at certain times.

Longer trains would be nice, but on existing tunnel lines its difficult to implement once built and rarely is as a result. Surface and viaduct is much more viable for extension.

Quad track on south Line
Hex track on western then Quad
Quad on north (partial)
Rest are mostly double track

And even this isn't enough and they are sharing tracks on some track pairs with trains with a different stopping pattern.

DD are being deployed in a very narrow part of the world and Luxembourg is basically a regional station stop for a line from Germany so I wouldn't count it (yes I've been there, I parked at the station). And again dear Mytone, the bulk of what you quoted is regional or outer suburban lines which no one has ever argued against. The rest of the RP forum is talking about inner suburban commuter, mostly underground. One day I hope you actually travel and learn the difference.

DD stock is far more specific in design than SD and modern SD design was more closely unified than DD. Sydney is already a DD stock island in the DD world.  Each batch is designed for only Sydney and basically would need to be rebuilt from ground up to be used in EU due to different loading gauge, length, min curve radius width, platform height etc etc. There will always be something. Sydney is already unqie being only 20m in car length.