Can loop service trains be separated by less than 2 minutes?

 
  Gwiwer Rt Hon Gentleman and Ghost of Oliver Bulleid

Location: Loitering in darkest Somewhere
Computers have replaced human signallers on main line UK railways at many locations with 100% safety records since around 20 years ago.

SSI (Solid State Interlocking) is one such system, firs used IIRC at Leamington SPa, a junction station with reasonable traffic flows and conflicting moves.  In very simple terms three independent computers manage the system and all three must agree with each other before a move is set up or signalled.  If there is a conflict then human intervention is requested from a remote supervisor, again IIRC located in Birmingham.  

No incident has yet been attributed to an SSI failure.  The system is now in wider use and has been modified and developed to take advantage of current software and electronics.

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  psr85 Chief Commissioner

Location: Sandringham Line, Melbourne
Computers may just be safer than people. But I do foresee a problem with their use.

It is a strange thing, but I don't think people will trust computer to get them home safely, even if it is statistically safer. Well not in the near future.

As the kids of today grow up and become the leaders of tomorrow, perhaps we will see a change in this mindset. I'd hazard a guess that most school leavers these days [/old man mode] have a much better understanding of computers than school leavers 5 years ago. Not to mention those who left 15 years ago.

Times will change, but not for a little while yet. I think too many people believe that computers could turn evil and revolt against us all.  Rolling Eyes
  DMU Dave Train Controller

Location: Hawthorn, VIC
The Victoria Line on the London Underground was opened in 1967 with Automatic Train Operation.  Basically the driver just opens and closes the doors and presses an all-clear button, then the ATO system "drives" the train between stations.  As has been pointed out, the Docklands Light Railway is also computer controlled.

Similarly, platform edge doors (PEDs) are used in many underground and metro systems worldwide, including London (Jubilee Line Extension) and Singapore to name just two.

Having said the above, according to Wikipedia (that reliable source!) the Victoria line still only has a 2-2.5 minute headway in peak times.  Does anyone know whether there are shorter headways on other tube lines and, if so, what technology is used?  Having travelled on the tube pretty often it certainly feels like headway is less than two mins when you're standing at one of the busier stations during peak time.  But I've never actually timed it.

Regards
DMU Dave
  Shacks Ghanzel

Location: Sir Big Lens of the Distant Upper Hunter
2 minute running between trains in the loop is old stuff. Get your hands on a timetable from 1988 for the northern loop, from FSS you had the 1512 Williamstown, 1514 Upfield, 1516 Brodameadows, 1518 St Albans, then there was a bit of a gap with a Upfield at 1531, 1533 Williamstown, 1535 Broadmeadows, 1539 St Albans. There were other times where the Northern loop had 2 minute running but I can not recall them. Werribee trains ran the express and went via SSS and North Melbourne.
  Gwiwer Rt Hon Gentleman and Ghost of Oliver Bulleid

Location: Loitering in darkest Somewhere
DMU Dave, refer to my posts just above.  Almost all central parts of the London underground system are now capable of signalling trains at around 45-second intervals and in some cases even closer.  

Station dwell time is the main constraint, but the Central line refurbishment has proven that very close headways can be achieved and dwell times actually reduced.  Fewer people have time to arrive on the platform before the next train, which consequently doesn't get packed to sardine can conditions, and may manage to serve all stations through the central area with only 10 - 15 second stops.

Compared with a standard 20 second stop that equals a saving of around 1 - 2 minutes by each train over the Stratford - White City section permitting at least 2 additional pathways per hour to be created.

The Victoria Line was opened in 1967 using early 1960's technology; the Central Line refurbishment uses mid-1990's technology which is vastly different.  The Victoria Line is also due for a full line refurbishment over the next couple of years prior to the retirement of its original 1967 stock and replacement with 2007 stock.  As part of this the permissable headways will be reduced to around 45 seconds from the present 2 minutes.  The higher line speeds gained by the easy curves of the Virctoria Line comapred with other lines will not permit anything closer.
  The Met Chief Commissioner

Location: 37.55-S /145.01-E


The systems above - do not have any passenger interfering infrastructure (except ticketing and the doors).

Nor do their systems have any barrier (like Hong Kong or Singapore) between station to train.
"The Met"


I'm not quote sure what you mean, but London at least uses a ticketing and entry system almost identical to Melbourne with entry barriers; some tube stations also have sliding doors at the platform edge and a barrier between the train and the platform making it impossible to press up close to the train and to only enter and leave by the doorways.
"Gwiwer"


I more specifically meant station barriers between trains, as mentioned above. sorry for the confusion.


The issue with Melbourne's loop capacity is largely the signalling system, and to a lesser degree the finite capacity of Flinders Street being used as a terminus with trains standing typically for 5 or more minutes at each platform.
"Gwiwer"


I still like my idea of running the system, with more trains terminating at Southern Cross (or at least more of them), running direct Clifton hill and Caulfield Group to Flinders, and run super-frequent shuttles between Richmond - North Melbourne, and another super-frequent shuttle purely around the Loop - not that my idea is over generalised - AND - HAS been discussed threads far away from this, and needs no more further discussion.


High passenger volume is common to many urban systems; some cities expereince better manners than Melbourne where holding doors open is becoming endemic.
"Gwiwer"


Ahhuh...  Evil or Very Mad

]
Station dwell time is the main constraint, but the Central line refurbishment has proven that very close headways can be achieved and dwell times actually reduced. Fewer people have time to arrive on the platform before the next train, which consequently doesn't get packed to sardine can conditions, and may manage to serve all stations through the central area with only 10 - 15 second stops.
"Gwiwer"


Hence our problem is rather worse. We have many who have to stand, or wake quite a distance compared to Londoners... Hence our extended waiting times, and perhaps a little less efficient running.


The higher line speeds gained by the easy curves of the Virctoria Line comapred with other lines will not permit anything closer.
"Gwiwer"


Hmm, well we could always revamp Flinders Street overduct...

But - we'll be saying hello to a mass amount of problems... (Though, it seems that our system could be slightly operable with my idea above of running the system...) - give or take we'll need tracks between FSS/SCS
  DMU Dave Train Controller

Location: Hawthorn, VIC
DMU Dave, refer to my posts just above.  Almost all central parts of the London underground system are now capable of signalling trains at around 45-second intervals and in some cases even closer.
"Gwiwer"


Thanks, Gwiwer - very informative post.  Next time I'll read your previous posts properly as well!

Regards
DMU Dave
  station street Chief Commissioner



The issue with Melbourne's loop capacity is largely the signalling system, and to a lesser degree the finite capacity of Flinders Street being used as a terminus with trains standing typically for 5 or more minutes at each platform.
"Gwiwer"


I still like my idea of running the system, with more trains terminating at Southern Cross (or at least more of them), running direct Clifton hill and Caulfield Group to Flinders, and run super-frequent shuttles between Richmond - North Melbourne, and another super-frequent shuttle purely around the Loop - not that my idea is over generalised - AND - HAS been discussed threads far away from this, and needs no more further discussion.
"The Met"


To my understanding - Sydney had a problem whereby drivers changed trains at a heap of different sttions - whereas in Melbourne it mainly occurs at Flinders Street.

Next - lets compare Melbourne to Sydney in terms of reliability etc... - who wins?

Although I like the idea of terminating at Southern Cross - I think that it would just create problems.

Instead - I would re-do the platform arrangement at Flinders Street and Southern Cross.

Firstly though- Williamstown trains and Sandringham trains.
EVERY Williamstown train should be an extension of a Sandringham train, as both lines are relatively short and don'ttake that long end to end, I think that they should use platform 10 at Flinders Street, and have only 1 minute recovery there.

Next - every second Sandringham train that does not form a Williamstown - will terminate in Platform 13 before turning around and forming another Sandringham.

From this - we have effectively used platforms 10 and 13. Platform 12 will remain a multi-use platform,

Platforms 8 and 9 will become Caulfield Loop platforms. Trains from Pakenham, Frankston and Cranbourne will arrive here, wait 5 minutes then operate to an alternate location, via the City Loop,

Platforms 6 and 7 will receive Direct Richmond traffic. To look in advance - about 7 Caulfield and 10 Burnley trains should run direct in the peak periods. These trains will arrive, turn around in the space of 7-12 minutes, then form another Richmond Direct train.

Platforms 4 and 5 will become wholly Northenr Loop trains. Trains will still have Recovery time at Flinders Street - each train should wait 3 minutes before continuing through the loop.

Platforms 2 and 3 will remain Burnley Loop trains only - with the same 3 minute recovery period.

Platform 1 will also remain Clifton Hill group only - however more sue should be stretched to platform 14.

Southern Cross is where the Northern Group can potentially gain mroe robustability.

Platforms 9 and 10 will remain as now.

Platforms 11 and 12 will BOTH become Northern Loop platforms - however I am still undecided whether it should also take over the Caulfield viaduct or not - subseuently shoving Daulfield over one, onto the new viaduct. However it would have to be bi-directionalised.

Platform 13 will then become the Caulfield platform

Platform 14 will become Williamstown and V/Line trains

Platforms 15 and 16 will also become Williamstown and V/Line trains.

This however creates a bottleneck - if the Northenr Group consumes 2 viaducts. If the Caulfield loop is tobecome high-frequency every 2 minutes tyle of loop - then we really only get one track for Northern Direct trains (With the other new viaduct track being bi-directionalised aswell) - this leavs us with 2 options.

1) Using The New Viaduct plus the two Southern-most Viaduct tracks as 4 bi-directional lines for use by 2 loops and 1 direct service. By consistant alternation we can probably acheive a slightly higher capacity - however our robustability goes down as Caulfield and Northenr Group trains will become interlocked.

2) Leaving the viaduct configuration as is - however with congestion still gaining on the Northern Group Tracks

3) Constructing 1 more viaduct between Flinders Street ad Southern Cross - or 2 to get maximum benefit. The 3 existing loops that run Clockwise would then get a train about every 2 minutes, makign them locked out
The existing 5 would go to:
2 to the Northern Loop
3 to Northern Direct trains
Northern Direct trains include V/Line trains

This would also provide enough capacity for an AirPort rail link - offcourse running direct...

Just my 2 cents worth...

  -   Station   Street
  John of Melbourne The Ghost of George Stephenson

Location: Melbourne suburbs
Track circuits return signals to stop immediatley the first set of wheels pass the signal circuit.
There are clearance points that determine that a train has moved off a section of track and allow the points to be altered.
Air operated points take about .3 of a second to throw. Circuit proving should then happen at the speed of light but with modern technology does not. It should all happen in the space of a few seconds once the previous train is clear.
The old Melbourne Yard area controlled by the West Tower is undoubtedly the fastest I have ever seen things happen. It is very fast if the signaller is 'on the job'.
By comparison the modern signalling technology that has been put in at Clifton Hill, Heidelberg and Ringwood is apallingly slow.
Over to an expert to explain the difference between the signalling at West Tower and Westrace signalling.
"Rocket"

I had put modern signalling delays down to increased overlaps and/or timeouts.  Are you suggesting that there are more factors than those delaying modern signalling?
  John of Melbourne The Ghost of George Stephenson

Location: Melbourne suburbs
As originally signalled the loops are signalled theoretically for 24 trains per hour which is one every 2.5 minutes. IIRC the only loop that is single tracked throughout (no points) is the Burnley Loop.

The others all have Y junctions and dual exit ramps at at least one end - Caulfield loop at Richmond end, Clifton Hill loop (as City Circle under Flinders St currently not regularly used, but will be used regularly again when one way running instituted on Clifton Hill loop in a clockwise direction), and Nth Melbourne Loop at Nth Melbourne station.

The capacity of 24 trains per hour is reduced to something like 16 per hour once the traffic is spread over the two exit points.  Government has announced loop will be resignalled to allow more trains to be put through, but also in future it would seem sensible to run some trains direct to Flinders St in peak hours when loops are at their new higher signalled capacity.
"kuldalai"

I don't know of any reason that a junction in the loop would delay trains exiting the loop.

However, signalling changes a few years back did impose a delay on trains entering the loops with junctions in them.
  northbritish Chief Train Controller

psr85

As a former IT person (now retired) I have always laughed at those scenarios of the "killer" computers because someone would have had to program it and I thought how would you test it, have a small scale test on Fiji LOL.

London transport is great 2 minute headways multiple connections great way to get around and the oyster card is superb.

I have a video of me "driving" a DLR train, (just pressing screw heads that passed for brake and controller).

But we did have a DLR guy come in and unlock the panel and "drive" on account of a disruption.
  psr85 Chief Commissioner

Location: Sandringham Line, Melbourne
psr85

As a former IT person (now retired) I have always laughed at those scenarios of the "killer" computers because someone would have had to program it and I thought how would you test it, have a small scale test on Fiji LOL.
"northbritish"
Don't get me wrong, I would be more than happy with a computer in control of my train, as you say, someone has to program it. But I dare say there would be lots of people out there who believed the computers could develop thoughts and emotions. Hollywood is probably to blame for that.

I guess once the oldies die out and the kids of today know everything about computers, we will see them driving trains. After all they don't call in sick, and they don't have to swap with another computer if they have worked over their allocated hours. I'm guesing by then they won't break down and they will be far more reliable.
  Dreadnought Assistant Commissioner

Location: Oooh, look! [Pointing upwards] An eagle!!
Anyone who is happy having a computer driving their train has obviously never seen the original Thunderbirds TV series.....

Cheers,
Dreadnought

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