What's the fastest accelerating tube stock?

[OneTrackMinded]

What train (revenue service) on the London Underground has the fastest acceleration? The most common go to is the 2009 Stock or full power unlocked mode on the S stock, but there doesn't seem to much information on how the 96 and 95 contend for example.

 

[Nym]

Passenger fleets or including the engineering vehicles and non-passenger carrying vehicles?

 

[OneTrackMinded]

Passenger fleets or including the engineering vehicles and non-passenger carrying vehicles?

Those in revenue service, so passenger fleets

 

[Silent]

What train (revenue service) on the London Underground has the fastest acceleration? The most common go to is the 2009 Stock or full power unlocked mode on the S stock, but there doesn't seem to much information on how the 96 and 95 contend for example.

Not researched but I notice the 2009 stock seems faster accelerating and faster stopping the 1996 stock although the 96 stock has a higher top speed. And I also wonder if the S Stock actually has a different motor or slightly different to the 09 stocks. It might be the platform environment but it seems like the 2009 stocks have a louder whine, as they begin to move, compared to the S Stocks. Also the 2009 stock is louder when standing at a station.

 

[Dstock7080]

2009 Stock and S Stock have slightly different motors being:
LT201 Bombardier Mitrac
MJB_200-93 Bombardier Mitrac
respectively.
They have different gear ratios too.
The louder sound of 2009 Stock while stationary would be the air-circulating fans for the saloon.

 

[OneTrackMinded]

2009 Stock and S Stock have slightly different motors being:
LT201 Bombardier Mitrac
MJB_200-93 Bombardier Mitrac
respectively.
They have different gear ratios too.

According to what I’ve read and specification wise despite the slightly different motors they have the same acceleration capabilities (excluding when s stock is under legacy signalling), although the S Stock can visually appear slower due to its larger size

 

[Silent]

According to what I’ve read and specification wise despite the slightly different motors they have the same acceleration capabilities (excluding when s stock is under legacy signalling), although the S Stock can visually appear slower due to its larger size

Yep, I just saw this with a Beno video I watched comparing S stock full acceleration with a 2009 ts acceleration, it's about the same. Although s stock does have a higher top speed.

 

[bramling]

What train (revenue service) on the London Underground has the fastest acceleration? The most common go to is the 2009 Stock or full power unlocked mode on the S stock, but there doesn't seem to much information on how the 96 and 95 contend for example.

I don’t have any technical info to hand, but I’d suggest that a 95 stock can accelerate not far short of as fast as 09 stock. 96 stock has always felt more sluggish.

Would certainly be interested in some figures comparing these stocks between themselves and to the 09/S stocks.

 

[Silent]

I don’t have any technical info to hand, but I’d suggest that a 95 stock can accelerate not far short of as fast as 09 stock. 96 stock has always felt more sluggish.

Would certainly be interested in some figures comparing these stocks between themselves and to the 09/S stocks.

I hardly use the 95 stock but wouldn’t be surprised. I think the 96 stock accelerates slower than the 09 stock but if s stock has same acceleration and I know the acceleration is capped with older signalling maybe I overestimate how fast the 09 stock accelerates in comparison to a 96 stock? But 96 definitely seems slower on approach although still fast generally. I don’t use the 95 stock so can’t really say.

 

[OneTrackMinded]

Would certainly be interested in some figures comparing these stocks between themselves and to the 09/S stocks.

That’s the aim of this thread

acceleration is capped with older signalling maybe I overestimate how fast the 09 stock accelerates in comparison to a 96 stock

Both the Victoria Line and the Jubilee line have a modern ATO signalling system throughout so they don’t have caps

 

[rebmcr]

Paging @Railperf (who might know)...

 

[Nym]

That’s the aim of this thread

Both the Victoria Line and the Jubilee line have a modern ATO signalling system throughout so they don’t have caps

The ATO used on the Jubilee Line (Also Northern Line and DLR) has acceleration caps built into the software in addition to the physical and software limitations of the train itself.

Given this question is limited to in service passenger fleets, and is I assume relating to the maximum acceleration across the full range, it would likely be one of the four AC traction from new stocks.

It is unlikely to be the 1996TS since the 7th car, and given the GTO Traction drives with very similar to Northern Line motors, that would leave the Northern Line in contention, but the aforementioned ATO limits may cause issues.

2009TS and S Stock both have "Very similar" specification motors at 75MW each (https://www.whatdotheyknow.com/request/1996_tube_stock_technical_drawin/response/590412/attach/3/RS Info Sheets 4 Edition.pdf).

Given the drive systems are essentially the same, but with different software limits, the numbers 1m/s/s and 1.14m/s/s have been thrown around as the hard limits within the systems, with 2009TS does hit (following the jerk rate (rate of change of acceleration) limitations) within around 15-20mph before hitting power limit to overcome the systems resistances.

S Surface is (was) limited to more like 0.5-0.7m/s/s on surface sections in line with lessons learned on 1992TS external running with similar on the tunnel sections to 2009TS, but only when on ATO. Now given the ATO was meant to be DTG-R (Distance to go Radio) a long long time ago, it would have achieved the same system limits (1m/s/s or 1.14m/s/s) as 2009TS before power system limitations. It may or may not now on the 2nd iteration of "CBTC" to be attempted to be implemented on the SSL network, not the right choice for a complex inter-worked network in my opinion, but there weren't many companies left to change the contract to.

So on an even ground, open section, with limits applied as should be for external running, all AC traction motored units should be the same up to around 12-20mph at their respective jerk and acceleration limits (which 2009TS doesn't have technically on the surface as it does not have a surface running mode per-ce).

After that, if we ignore resistances, it would come down to power per unit mass and maybe a bit of gear ratios. If we look at resistances, then it's anyone's game based on air resistance, tunnel profiles and bearing / maintenance quality. Even the strength of the power supply will play into this with some level of significance.

 

[Silent]

That’s the aim of this thread

Both the Victoria Line and the Jubilee line have a modern ATO signalling system throughout so they don’t have caps

Yeah I meant the s8 stocks acceleration is capped in the outer sections and noticeably accelerates slower than Jubilee line Wembley Park to Finchley Road. I probably was unclear though.

 

[J-2739]

Not too related to the total, but I've always felt the 1992TS to have the greatest deceleration of all the tube stock. It is the only line I have used in which the trains seems to enter the platform at top speed. Even the 2009TS appear to slow down earlier, though I don't know if this is a function of the signalling rather than the stock?

 

[Nym]

Not too related to the total, but I've always felt the 1992TS to have the greatest deceleration of all the tube stock. It is the only line I have used in which the trains seems to enter the platform at top speed. Even the 2009TS appear to slow down earlier, though I don't know if this is a function of the signalling rather than the stock?

2009TS enter some platforms at full speed.
You feel it more on DC Motored 1992TS because the Jerk Rate limitation is less errr effective

 

[Silent]

2009TS enter some platforms at full speed.
You feel it more on DC Motored 1992TS because the Jerk Rate limitation is less errr effective

What is jerk rate. Is it how likely you are to feel a motor jerking?

 

[rebmcr]

What is jerk rate. Is it how likely you are to feel a motor jerking?

Jerk is the rate of gaining acceleration, similarly to how acceleration is the rate of gaining speed.

There are also more units continuing down the "rate of rate of rate of..." ladder.

After that, if we ignore resistances, it would come down to power per unit mass and maybe a bit of gear ratios.

Let's come at this from a different angle. The rail speed record of 574kmh was set by a specially-configured TGV train with trailer cars and limits removed.

If you were to pick an LU passenger stock to specially configure, and a section of line to set an acceleration record on, what would be the frontrunner choice?

 

[bramling]

Not too related to the total, but I've always felt the 1992TS to have the greatest deceleration of all the tube stock. It is the only line I have used in which the trains seems to enter the platform at top speed. Even the 2009TS appear to slow down earlier, though I don't know if this is a function of the signalling rather than the stock?

I think this is an illusion, as the 92 stock IIRC never exceeds 65 kph in tunnel sections, whereas the 09 stock certainly reaches 50 mph. So the Victoria Line would have to slow down a bit earlier, whereas the Central Line can quite happily start braking roughly at a tailwall and still have plenty of room to stop. Worth also mentioning that the Central Line tends to have a climbing gradient on the approach to most tunnel platforms, whereas on the Victoria Line it wasn’t always possible to achieve this.

Anecdotally I’d say the 95 stock braking is very slightly sharper than 92 stock, but there’s not much in it. 95 stock has become more inconsistent in recent times however, most trains have really good sharp brakes, but there’s some which are conspicuously weak to the point where they can struggle to meet the maximum braking profile demanded by the TBTC system.

 

[Nym]

Jerk is the rate of gaining acceleration, similarly to how acceleration is the rate of gaining speed.

There are also more units continuing down the "rate of rate of rate of..." ladder.


Let's come at this from a different angle. The rail speed record of 574kmh was set by a specially-configured TGV train with trailer cars and limits removed.

If you were to pick an LU passenger stock to specially configure, and a section of line to set an acceleration record on, what would be the frontrunner choice?

The MPU or D78 RAT on the Met Fasts, cold day, low humidity, early morning.
Scrap size wheelsets, set the tap changers high on the subs and “modify” the volt-amp relay and a few other bits in the traction gear.

Fettling the passenger fleets, same line space, but would be a toss off between 09TS or S Stock

 

[D365]

2009 Stock and S Stock have slightly different motors being:
LT201 Bombardier Mitrac
MJB_200-93 Bombardier Mitrac
respectively.

What does MJB stand for?

 

[J-2739]

2009TS enter some platforms at full speed.
You feel it more on DC Motored 1992TS because the Jerk Rate limitation is less errr effective

I think this is an illusion, as the 92 stock IIRC never exceeds 65 kph in tunnel sections, whereas the 09 stock certainly reaches 50 mph. So the Victoria Line would have to slow down a bit earlier, whereas the Central Line can quite happily start braking roughly at a tailwall and still have plenty of room to stop. Worth also mentioning that the Central Line tends to have a climbing gradient on the approach to most tunnel platforms, whereas on the Victoria Line it wasn’t always possible to achieve this.

Anecdotally I’d say the 95 stock braking is very slightly sharper than 92 stock, but there’s not much in it. 95 stock has become more inconsistent in recent times however, most trains have really good sharp brakes, but there’s some which are conspicuously weak to the point where they can struggle to meet the maximum braking profile demanded by the TBTC system.

Come to think of it, these also corroborates with my experience. I didn't know the 1992TS were that speed restricted in the tunnels, but that's the only explanation that makes sense.

The 2009TS do seem to ride a lot smoother, so maybe I wasn't giving them full credit. Both them and the 1992TS are still great performers in my eyes!