DLR B23 Stock (CAF Inneo)

[DLRnotDave]

I'm also a regular DLR user since I moved to Docklands 27 years ago and I have experienced only a couple of overruns in that time so I can understand what you mean and that you can't equate "normal" with "frequent". However I equate "normal" with a situation which has been anticipated and can be dealt with as part of the day-to-day routine, for which operators have been trained for and doesn't require attention from engineers or other support staff or shutting down the railway.

Spot on, as SelTrac relies on counting wheel revolutions between loop crossovers for positioning so it's particularly sensitive to wheelslip causing them to go NCT.

209 eventually got pulled from service today after going non-communicating multiple times in the rain.

Doesn't exactly bode well

Ths B23s were proving to be very troublesome in the rain, but the overrun that caused the withdrawal from service will have been something more significant.

The 'soft launch' was the month of dawn to dusk reliability proving, 209 is an accepted train running a timetabled service from 6am till past midnight every day with just a PSA onboard.

One of the reasons the fleet was so delayed was ATO adhesion issues, so for it to be failing now is disconcerting even if it is (hopefully) an easy fix.

The system doesn't have the luxury of breathing room at the moment, a reduced timetable is already in operation due to its rolling stock shortage, with more B92s getting closer to their millage limits as time ticks on.

Any further issues that disturb the aggressive rollout over the coming months (not that I'm implying there will be) will cause a massive headache.

Oof...

 

[Taunton]

Not only a reduced timetable, but many of the services have been knocked back from 3-car to 2-car. Along with the timetable reductions it's a notable capacity reduction; compared to before this started the Beckton branch now only has one third of previous capacity, a 2-car train every 10 minutes compared to two 3-car trains, which causes particular issues with major Excel exhibitions. Given that City Hall is now on that line, someone has surely noticed.

Seltrac is quite widely used across the rest of the TfL network, and indeed around the world, without stopping position issues, so one wonders what the uniquely DLR aspects are.

 

[JCO1406]

I wouldn't be surprised if Lewisham services go down to 2 cars as more B90s need to be withdrawn. Lets just hope that the issues with the B23s gets resolved soon! I would love for the Beckton line to go back to 12tph. Lets just say the current 6tph isn't exactly pleasant.

 

[Snow1964]

I wouldn't be surprised if Lewisham services go down to 2 cars as more B90s need to be withdrawn. Lets just hope that the issues with the B23s gets resolved soon! I would love for the Beckton line to go back to 12tph. Lets just say the current 6tph isn't exactly pleasant.

Do they need to be withdrawn, or is it just saving money by not doing maintenance and repairs at this stage, and withdrawal could be later.

It is not like the 1987 hard deadline for asbestos, or non compliance with a disability rule which has absolute deadline date.

 

[35B]

Do they need to be withdrawn, or is it just saving money by not doing maintenance and repairs at this stage, and withdrawal could be later.

It is not like the 1987 hard deadline for asbestos, or non compliance with a disability rule which has absolute deadline date.

It's technically the former, but where the practicality of doing the repairs when overhauls are due is a major part of the issue. That's not just about cost, but also about the ability to procure what would be required.

 

[Thirteen]

It's technically the former, but where the practicality of doing the repairs when overhauls are due is a major part of the issue. That's not just about cost, but also about the ability to procure what would be required.

Overhauling the B90s is not going to happen at this stage.

 

[35B]

Overhauling the B90s is not going to happen at this stage.

I didn’t suggest it would, merely the nature of the “must”

 

[DGP]

I didn’t suggest it would, merely the nature of the “must”

I thought I'd read somewhere that the existing overhaul facilities had been demolished to make way for stabling the new stock and a replacement overhaul facility could not be built until the existing stock had been scrapped.

There now follows an interesting speculation thread about what could happen if more of the B90/B92 stock had to be scrapped before sufficient B23 stock was available.

 

[ScotGG]

How many of the older stock has already been scrapped, and how much miles do the remaining units have in operation until exams I wonder?

Autumn is often the busiest time of the year and running around with short trains isn't helping at all.

 

[Taunton]

Given the bulk of the new trains have been stored in Spain for some years now, one wonders how this will impact on their reliability. Those airlines that stored aircraft over lockdown in supposedly "ideal" conditions nevertheless reported significant component failure rates and increased costs once they brought them back. In London the Standard Tube stock for the Central Line extensions which were stored in WW2 were real maintenance hogs when brought back, even in comparison to their fellows which had worked with minimal maintenance throughout, and by some accounts never worked with proper reliability again until final replacement and withdrawal in the early 1960s.

 

[DLRnotDave]

Do they need to be withdrawn, or is it just saving money by not doing maintenance and repairs at this stage, and withdrawal could be later.

It is not like the 1987 hard deadline for asbestos, or non compliance with a disability rule which has absolute deadline date.

The plan had been to replace B92s as they approached their scheduled heavy overhaul (a big job for a train you're about to scrap) the delay in B23s mean lots of B92 are coming up on their millage limits hence the control measures like the timetable reduction and 2-car services

Seltrac is quite widely used across the rest of the TfL network, and indeed around the world, without stopping position issues, so one wonders what the uniquely DLR aspects are.

Wheelslip causing trains to go non-communicating is an know flaw of SelTrac, that's why the Jubilee and Northern lines have such slow breaking rates on the open air sections, the DLR is not any worse off from it AFAIK, but the B23s specifically were very susceptible to it (again, outside of the overrun incident)

 

[NCT]

Is it the case that the B23's braking curves need to be further adjusted to Northern/Jubilee open air section levels of gentleness, or is the issue a bit more complicated / fundamental than that?

 

[IslandDweller]

I moved to the Isle of Dogs one week before the DLR opened, and have been using it ever since. Overruns are not normal (in most people's understanding of the term) but nor are they unknown.
When the system was brand new, using the single car stock that was long ago shipped to Germany, overruns happened in slippery conditions and I suspect the issue was crude anti lock braking system. One the current stock, overruns still do happen occasionally. If I guessed, I'd say I experience one or two per year, and are only a very small distance. The train captains are used to this and are slick at resetting the train and repositioning it (if needed - sometimes they appear to be able to open the doors if the train is only slightly off the correct mark).
My working career was not in railways but it did involve major change projects with massive software dependency. Project teams by their nature are short term entities and don't have the "collective memory" of what went wrong on previous projects. They also often have an "optimism bias". It is a failing of big projects the world over that too few managers are given the time and resources to properly study the issues that were encountered in previous deployment phases. And while I have no knowledge of the personnel leading this project, I have encountered many examples where the top man (and it usually is a man) makes it clear he doesn't want to hear bad news, so problems get concealed instead of solved. And then those problems blow up badly when they can't be concealed any longer.

 

[torontoaddick]

Is it the case that the B23's braking curves need to be further adjusted to Northern/Jubilee open air section levels of gentleness, or is the issue a bit more complicated / fundamental than that?

In general the B23 brake rates are already set to be lower than on the Jubilee/Northern open sections.

 

[NewcastleBrown]

What I don't quite get is why the mileage limit for the old trains is so 'hard' a barrier - it's not like a magic switch is flipped at that point, and you would imagine with potentially an enhanced inspection routine and a greater tolerance for failures you could keep them running for a bit longer

 

[Taunton]

Seltrac was initially designed for systems without driven wheels. Intended originally for the German Maglev, its first main application was on the two intermediate rapid transit systems in Canada, in Toronto and the Vancouver Skytrain, both of which use linear motors and a centre-track reaction rail. I remember the Vancouver system from the year it opened in 1986, and being struck by very close headways and reversing in about 5 seconds, all things the system seems to have lost (though the DLR can do a very quick reversal at the termini if they have to). But surely with their widespread adoption since then they are not thrown by wheelspin.

 

[35B]

What I don't quite get is why the mileage limit for the old trains is so 'hard' a barrier - it's not like a magic switch is flipped at that point, and you would imagine with potentially an enhanced inspection routine and a greater tolerance for failures you could keep them running for a bit longer

That often depends on what the manufacturers will underwrite, if they will. Where components have fatigue life, the inspections required may well be a challenge. If that’s on a component where failure is liable to mean a derailment, those asked to sign off on this are likely to be very cautious

 

[ChristopherJ]

My understanding this 'overshoot' was more of a fault with the CBTC / ATO system than the physical train brakes. The B23s need a slighty longer and lighter braking distance coded into SelTrac, then good to go.

I've travelled regularly on the DLR for 35 years and overshoots do occur - especally in wet or leaf fall weather - it's not unknown. They're not called 'light' rail vehicles for nothing!

Remember when LUL introduced the Central Line ATO system, 92TS trains would run at full speed and braking in all weather conditions outside to Epping/West Ruislip. Platform overshoots happened on an hourly basis.

 

[TRAX]

My understanding this 'overshoot' was more of a fault with the CBTC / ATO system than the physical train brakes.

I agree with you. Narrowing it down to just the brakes was the easy and only explanation the general media was capable on giving.

 

[DLRnotDave]

Christmas service cuts:

• Bank/Lewisham route reduced to 2-car operation from 13/12 till 04/01
• A Saturday service will operate on weekdays between 22/12 and 02/01
• Sunday service on New Year's Day
• Current service restored on 05/01

 

[Snow1964]

My understanding this 'overshoot' was more of a fault with the CBTC / ATO system than the physical train brakes. The B23s need a slighty longer and lighter braking distance coded into SelTrac, then good to go.

There is a comment on page 20 of the Commissioners report in the papers for next weeks TfL Board meeting.

It says happened on one isolated occasion, on one train, whilst wet, and that the three new trains have been temporarily withdrawn whilst it is investigated as a precautionary measure.

https://board.tfl.gov.uk/documents/s25368/board-20251203-item05b-Commissioner%20Report.pdf

No indication to the Board, if just the one train had a fault reducing braking, or the location had stopping distances too tight.

 

[Thirteen]

This weekend's DLR closure mentions signal testing as a reason which makes me wonder if they're planning to test the B23s in order to return them to service,

 

[burneside]

Christmas service cuts:

• Bank/Lewisham route reduced to 2-car operation from 13/12 till 04/01
• A Saturday service will operate on weekdays between 22/12 and 02/01
• Sunday service on New Year's Day
• Current service restored on 05/01

Operating 2-car trains on the Bank-Lewisham branch will be horrendous, they are already much more crowded because of the suspension of the Stratford-Lewisham service

 

[Taunton]

This weekend's DLR closure mentions signal testing as a reason which makes me wonder if they're planning to test the B23s in order to return them to service,

This has been going on at weekends for a very considerable time now - nearly 3 years.

 

[torontoaddick]

This weekend's DLR closure mentions signal testing as a reason which makes me wonder if they're planning to test the B23s in order to return them to service,

This weekend is planned axle counter upgrade works, not related to B23 testing.

 

[Taunton]

This weekend is planned axle counter upgrade works, not related to B23 testing.

There seem to be a range of disruptive works all going on. For example Tower Gateway station is closed every weekend from now to the middle of January (at least). It's almost as if engineering has forgotten that the purpose of the system is to actually provide a service to the travelling public.

 

[Mattplans]

There seem to be a range of disruptive works all going on. For example Tower Gateway station is closed every weekend from now to the middle of January (at least). It's almost as if engineering has forgotten that the purpose of the system is to actually provide a service to the travelling public.

Not the end of the world! Just wish they diverted the Beckton trains to Bank instead of restarting them from Poplar

 

[Geogregor]

Christmas service cuts:

• Bank/Lewisham route reduced to 2-car operation from 13/12 till 04/01
• A Saturday service will operate on weekdays between 22/12 and 02/01
• Sunday service on New Year's Day
• Current service restored on 05/01

So, do they hope to have the new trains running in January?

 

[Snow1964]

So, do they hope to have the new trains running in January?

In theory, if they need to ration the mileage of existing fleet, have the option of putting a few new trains out on days where weather forecast says will be dry all day. The TfL Board papers confirm just a single event when wet, so appears to be no problem when dry.

But no doubt will be deemed too difficult operationally , or someone would say not enough caution and high risk so can't be done (even if risk is lower than dangers of overcrowded 2car units)

 

[DLRnotDave]

So, do they hope to have the new trains running in January?

This service reduction during a quieter part of the year is to buy more time that the existing fleet can sustain the current (already reduced) timetable into the new year AIUI.