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Victoria Line 'slow mode'

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Height106

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This is the second thread I have started about the Victoria Line, but I use it multiple times per week (including for work) so I am very aware of changes to its usually brilliant service.

Over the past 6 months or so there have been periods where some or all trains have been travelling slower than usual, particularly on the approach to stations. When it occurs, it seems completely random - some trains are still travelling at the normal speed, others will go slower for part of the route, while yet more will do so for the entire line. It is also hard to tell whether drivers are actually in control of this or not - I have witnessed duties running significantly late due to earlier or ongoing disruption, but still in the slower mode.

There seem to now be two 'modes' for the trains - the original, high speed one, and a slower one that always involves the exact same amended top speeds and braking routines, so clearly still automatic operation. As I said previously, many trains will jump between modes depending on the section of the line, which in of itself seems random.

This all started around when it emerged that noise levels on parts of the line were dangerous (October last year I believe), and a 'go-slow' strike by drivers was rumoured. However, there seemed to be no correlation between where the trains would go slower than usual and where the loudest parts of the line were. And between then and now, virtually every loud section of the line has now been remedied, so there is no reason for the trains to go slower from a noise standpoint.

The usual journey times can still be maintained in the slower mode, due to less time spent at stations in it, but presumably problems occur when trains are running late and trying to make up time, as well as potentially during peak times where much more dwell time is required at each station due to the chronic overcrowding (why the hell did they 'postpone' Crossrail 2?).

This problem has come and gone during the last six months. It has happened less recently - there was a period of over a month where I didn't witness a single train running slower, but seems to have resurfaced over the past few days, hence my curiosity.

As with my first thread about this line, just wondering if people more knowledgeable than me know why this has been occuring, and how much of it is down to individual driver choice?



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GFE

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There have been some reports that LUL have been trying various methods to prevent or slow down the noise developing in the first place.
It appears that a major factor is that ATO driven trains are very consistent with speed, braking and acceleration at any location - so perhaps they are trying to vary this?
 

notverydeep

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The Victoria has three 'run profiles' for the ATO to use, No Coast, Intermediate Coast and Full Coast. The timetable is designed for Full Coasting to be the normal mode, but the Automatic Train Regulation (ATR) can automatically (by selecting Intermediate Coast or No Coast for a given station to station link, or the controllers can manually recover by turning off the ATR / Coasting functions. A temporary speed restriction (TSR) was in operation south between Oxford Circus and Green Park from 2022 until October 2024 and this meant that recovery with coasting was always tricky, so it was switched off for much of this time. The line is now back to what is planned to be normal, although the coasting will still be off some of the time as the ATR makes adjustments or if there are a number of cancellations. Full Coasting adds between 8 and 10 seconds of run time on any given link, but time is included in the timetable to allow for this. With high frequency and very limited terminus recovery, this is how recovery time is scheduled on the Victoria line. The Victoria line timetable is normally quite effective at staying on time, unless there are incidents or a number of cancellations. In a few locations, the full coast profile was modified to allow a faster run in to high dwell time platforms to maintain throughput, but the previous slower approach is now the Intermediate Coast profile at these locations and can be used by the ATR off peak.
 

Height106

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The Victoria has three 'run profiles' for the ATO to use, No Coast, Intermediate Coast and Full Coast. The timetable is designed for Full Coasting to be the normal mode, but the Automatic Train Regulation (ATR) can automatically (by selecting Intermediate Coast or No Coast for a given station to station link, or the controllers can manually recover by turning off the ATR / Coasting functions. A temporary speed restriction (TSR) was in operation south between Oxford Circus and Green Park from 2022 until October 2024 and this meant that recovery with coasting was always tricky, so it was switched off for much of this time. The line is now back to what is planned to be normal, although the coasting will still be off some of the time as the ATR makes adjustments or if there are a number of cancellations. Full Coasting adds between 8 and 10 seconds of run time on any given link, but time is included in the timetable to allow for this. With high frequency and very limited terminus recovery, this is how recovery time is scheduled on the Victoria line. The Victoria line timetable is normally quite effective at staying on time, unless there are incidents or a number of cancellations. In a few locations, the full coast profile was modified to allow a faster run in to high dwell time platforms to maintain throughput, but the previous slower approach is now the Intermediate Coast profile at these locations and can be used by the ATR off peak.
Thank you very much for this, brilliant response. Knew that somebody more in the know would put my mind at rest on this topic!
 

edwin_m

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Probably not relevant to the fully underground Victoria line, but ATO systems often have a facility to reduce the braking rate on open air sections on days when wheel-rail adhesion is poor.
 

boiledbeans2

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Probably not relevant to the fully underground Victoria line, but ATO systems often have a facility to reduce the braking rate on open air sections on days when wheel-rail adhesion is poor.
On the Jubilee, the braking rate in open-air always seems slower than the tunnel section regardless of weather though.
 

Silent

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On the Jubilee, the braking rate in open-air always seems slower than the tunnel section regardless of weather though.
Has the deceleration rate in these sections been recorded? Do tunnels make the train seem faster because of closer distance between most things in a deep level station compared to outside.
 

Russel

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I recall last year either the drivers or unions said they were planning to driver the trains slower due to the noise, did anything ever come of this, if so, how, given the line is ATO?
 

boiledbeans2

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Has the deceleration rate in these sections been recorded? Do tunnels make the train seem faster because of closer distance between most things in a deep level station compared to outside.
It's noticeable because the "gear change" sounds from the 96TS motor/inverter sound slower in outdoor sections.
 

Height106

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I recall last year either the drivers or unions said they were planning to driver the trains slower due to the noise, did anything ever come of this, if so, how, given the line is ATO?
I don't think anything ever officially took place, most of the loudest sections of the line were remedied soon after the noise findings were released and action was threatened.

The trains are ATO, but a manual override is possible at low speeds - I suspect this is what would have taken place
 

bramling

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Has the deceleration rate in these sections been recorded? Do tunnels make the train seem faster because of closer distance between most things in a deep level station compared to outside.

It’s definitely a harsher brake rate in the tunnels, and same applies on the Northern Line.

I think LU have more or less given up on trying to improve the Seltrac brake rates in the open. Indeed there’s now a software tool that recommends temporary speed restrictions at times when problems are predicted as well.

So much for progress…

== Doublepost prevention - post automatically merged: ==

The Victoria has three 'run profiles' for the ATO to use, No Coast, Intermediate Coast and Full Coast. The timetable is designed for Full Coasting to be the normal mode, but the Automatic Train Regulation (ATR) can automatically (by selecting Intermediate Coast or No Coast for a given station to station link, or the controllers can manually recover by turning off the ATR / Coasting functions. A temporary speed restriction (TSR) was in operation south between Oxford Circus and Green Park from 2022 until October 2024 and this meant that recovery with coasting was always tricky, so it was switched off for much of this time. The line is now back to what is planned to be normal, although the coasting will still be off some of the time as the ATR makes adjustments or if there are a number of cancellations. Full Coasting adds between 8 and 10 seconds of run time on any given link, but time is included in the timetable to allow for this. With high frequency and very limited terminus recovery, this is how recovery time is scheduled on the Victoria line. The Victoria line timetable is normally quite effective at staying on time, unless there are incidents or a number of cancellations. In a few locations, the full coast profile was modified to allow a faster run in to high dwell time platforms to maintain throughput, but the previous slower approach is now the Intermediate Coast profile at these locations and can be used by the ATR off peak.

Must admit I’ve never fully understood how all this works on the Victoria Line. I seem to remember reading that the system as originally implemented calculated a coasting point, depending on how early the train was predicted to arrive at the next station, from where the train would then coast all the way until it met the final platform braking curve.

However I know the system was changed a few years ago. I’m very vague on it as what I’ve picked up is only from skim-reading documentation, however the system was changed from “coasting” to “cruising”, and certainly from then onwards I noticed a change, albeit I can’t really fathom out what the system actually does now!

One way or other, generally the Victoria Line system seems to work a lot better than some of the other ATC systems on LU, so those designing it clearly knew their stuff.
 

GFE

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I understand that a team is actively investigating the factors causing rail head "corrugation" and the resulting noise levels, so a revisit of ATO driving technic/speeds/controls on the various lines is indeed likely. Trials have been announced on the Northern line & ATO driving performing differently has been reported recently by Central line train drivers (on another forum).
 
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notverydeep

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However I know the system was changed a few years ago. I’m very vague on it as what I’ve picked up is only from skim-reading documentation, however the system was changed from “coasting” to “cruising”, and certainly from then onwards I noticed a change, albeit I can’t really fathom out what the system actually does now!

One way or other, generally the Victoria Line system seems to work a lot better than some of the other ATC systems on LU, so those designing it clearly knew their stuff.
The modified 'Cruise Coast' profile (which is effectively a redefinition of the Full Coast Profile) applies to the following links across the Victoria line:
Southbound
Finsbury Park to Highbury & Islington (AM Peak only)
Highbury & Islington to King's Cross (AM Peak only)
Warren Street to Oxford Circus
Green Park to Victoria

Northbound
Pimlico to Victoria (AM Peak only)
Green Park to Oxford Circus
Euston to Kings Cross (PM Peak only)

Each link has its particular timings (basically weekday peaks only) determined by the expected dwell time at the end platform, itself a function of the direction of the main passenger demand, otherwise the Intermediate Coast Profile is the default for these links. The Intermediate Coast profile was also modified in such a way that it became what was previously the Full Coast profile. Only two profiles can be available on each link aside from No Coast, so for these links the previous Intermediate Coast profile is no longer available.

Highbury and Islington Southbound was a significant problem for Victoria Line Upgrade part 2. The signalling of busier stations on the line was designed more, shorter track circuit sections to allow for the track behind a departing train to clear quickly for the next reoccupation* to start and these locations already had better reoccupation times. When the original Upgrade re-signalled, like the majority of the outer stations, passenger traffic at Highbury and Islington was lower than in Central London and dwell times correspondingly shorter. However, the first upgrade came just ahead of the huge expansion of frequency and capacity on the Mildmay (North London) line. That had caused traffic from the stations east of Highbury and Islington from the areas around Canonbury, Dalston and Hackney Central etc. interchanging onto the Southbound Victoria line to grow rapidly, causing a huge increase in Victoria line boarders at Highbury and Islington Southbound. This led to increased peak dwell time, extending the reoccupation time*. Cruise Coasting was the solution to this problem that avoided what would effectively have been a re-signalling of the line through this platform and was applied at the other locations to add throughput recovery.

*Reoccupation time is the sum of Run Out time to the point where the route for the Run In can be cleared, Run In time either from rest at the "home signal" or from line speed at the "sighting point" and the dwell time. Note the conventional signalling terminology with the home signal often being a 'Block Marker' of some sort and the sighting point being the Automatic Train Operation braking point. The shortest reoccupation time is usually from rest (or at least a bit impeded). This is why trains often stop prior to entering busy platforms or terminal stations on Metros. It isn't the only reason on the Victoria line, as with little capacity for recovery time in the terminus platforms, some additional recovery time is often added on approach to the terminus as that is usually the least busy link.
 

ChristopherJ

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The Victoria has three 'run profiles' for the ATO to use, No Coast, Intermediate Coast and Full Coast. The timetable is designed for Full Coasting to be the normal mode, but the Automatic Train Regulation (ATR) can automatically (by selecting Intermediate Coast or No Coast for a given station to station link, or the controllers can manually recover by turning off the ATR / Coasting functions. A temporary speed restriction (TSR) was in operation south between Oxford Circus and Green Park from 2022 until October 2024 and this meant that recovery with coasting was always tricky, so it was switched off for much of this time. The line is now back to what is planned to be normal, although the coasting will still be off some of the time as the ATR makes adjustments or if there are a number of cancellations. Full Coasting adds between 8 and 10 seconds of run time on any given link, but time is included in the timetable to allow for this. With high frequency and very limited terminus recovery, this is how recovery time is scheduled on the Victoria line. The Victoria line timetable is normally quite effective at staying on time, unless there are incidents or a number of cancellations. In a few locations, the full coast profile was modified to allow a faster run in to high dwell time platforms to maintain throughput, but the previous slower approach is now the profile at these locations and can be used by the ATR off peak.
I'm a daily user of the Vic Line.

What's the policy for changing the run profile on the ATR function?

Sometimes the ATO will run at full linespeed (80kph) with no messing around, other days it coasts almost to walking pace before taking power again - very annoying when you're in a rush and the train is just p*ssing around coasting.

Can you tell the line controllers at Northumberland to stop messing about with it and leave it alone!!!
 

bluegoblin7

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Can you tell the line controllers at Northumberland to stop messing about with it and leave it alone!!!
If you’re an expert in railway operations, as the attitude of your post would suggest, you’ll know how to tell them yourself.

If you’re not an expert in railway operations maybe leave it all to those who are.

I’m sure you’d be the first to complain if you missed a train due to early running and extended headways if coasting wasn’t an option.
 

computerSaysNo

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It’s definitely a harsher brake rate in the tunnels
Does anyone know what proportion of braking capacity is used in various circumstances? I assume full service and emergency are both 100% capacity (i.e. maximum regenerative brake plus maximum disk brake, subject to wheel slide protection activity).
I assume the brake rate for normal stops is never set to demand 100% of capacity as each train will respond slightly differently depending on various efficiencies and passenger load etc, so if 100% were planned then there would be nothing left in reserve if a particular train was performing suboptimally.
 

bramling

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Does anyone know what proportion of braking capacity is used in various circumstances? I assume full service and emergency are both 100% capacity (i.e. maximum regenerative brake plus maximum disk brake, subject to wheel slide protection activity).
I assume the brake rate for normal stops is never set to demand 100% of capacity as each train will respond slightly differently depending on various efficiencies and passenger load etc, so if 100% were planned then there would be nothing left in reserve if a particular train was performing suboptimally.

I don’t think ATO uses 100%, simply because if full service braking is selected by the driver most trains will out-perform the braking curve - which is the same for both ATO and PM. That said, this assumes the system has been set up to use the harshest braking rate available in ATO, it certainly doesn’t in the open sections.

There’s certainly variability between trains, hence use of the word most! ;)
 

100andthirty

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THe maximum brake rate in service braking is 1.34 m/s2. The ATO seeks to deliver 1.15m/s2 average brake rate and needs to be able to vay the rate up or down to take account of gradiets and normal variations in the control loop. In manual driving the maximum brake rate available is 1.15 m/s2. The emergency brake rate is 1.34 m/s2.
 
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