New DLR rolling stock

The new trains probably had to have more bogies to share the extra weight of air-con kit without increasing axle weight on some of the historic structures.

"Inflexible, fixed rakes" is regarded as an advantage in this case. The inter-unit gaps waste space that could be used for passengers and the couplers are wearing out from coupling and uncoupling. The DLR needs more capacity, the only reason they don't run all the current services as three-car trains is they haven't got enough rolling stock to do so at the desired frequency. Previously passenger circulating capacity at Bank was a limiting factor on running more trains there, but this has now been resolved.

Regarding non-articulated stock. Remember that the DLR has some very tight curves and steep gradients. Articulation points are inherently less flexible than couplers between cars, so this may have been a factor.

I guess cab systems are a major cost of a train, and having a spare one or two riding around in a train much of the day is not a good use of funds!

I think either your choice of 90% is low or your definition of "modern" very loose. The TransPennine Express Mk5 stock worked in fixed rakes, though I'm not sure about the Caledonian Sleeper carriages. Prior to that it's the 1990s Mk4 stock, which operate in fixed rakes. Bringing it back on topic for this forum, everything currently operates as fixed rakes, indeed on the Central Line cabs have been harvested for parts and are now condemned to being within a train.

It looks as though the biggest problem with articulated stock, ie fixed rakes, is no longer an issue.

We should be able to look forward to some reduced-weight, highly-flexible trains for the DLR in future, once the message gets out.

Tube train cabs of the 1938 era were only a couple of feet deep, so narrow that I had to ride side-saddle to get my knees within the control desk. They only really featured a brake handle and a power controller. Modern trains provide a comfortable workstation, with controls for radio communications, passenger address, signaling interface, platform interface, safe door operation, etc etc. So they take up more space, and require a lot more investment in equipment which then requires maintenance. The fewer the better in a train. It's hard to imagine a time when shorter trains could operate as demand has increased throughout the day, and off-peak service intervals still allow travelers to turn-up and go. In the past a 30-minute service off-peak might have met demand on a branch, but was operated as a 15-minute service of half-length trains.

Almost but not quite. Even after the full deployment of the B23’s, including the extra Housing Infra Fund funded trains, the Stratford Int - Beckton service is planned to continue to be operated by short formed B07’s all day.

At the moment, I believe B23s will only operate from Beckton depot, so all "runs" that operate from Poplar will be B2007s. On the current schedule, the only route where all the trains operate out of Poplar depot is the Stratford (High Level) route. On all other routes, trains operate from both Poplar and Beckton depots. 

This is, of course, subject to change

Anyone heard the latest? The B23s seemed to be out and about during this weekend's closure, wondered if anyone knew whether we might see them in service next month as was hinted.

The two parties (customer and manufacturer) will have agreed a delivery schedule for test train(s) and production trains, but I expect that the choice of when to manufacture them is entirely the manufacturer's. The customer will only make the final payments for the train once the agreed acceptance criteria are met, and so it's not generally going to be financially relevant to them whether the trains are modified post-production line or not (unless there are significant differences in life expectancy and/or maintenance requirements).

Whoever makes the decision, it will include consideration of the likelihood and likely significance of required hardware modifications. My guess is that the DLR's much more modern, relatively compact, relatively homogenous network was seen as having a lower risk of this than the Piccadilly line. The differences from the manufacturer's platform (and how established that platform is) will also make a difference.

I've not had chance to watch this yet, but it has been recommended to me

Introduction of the new trains will not happen until "later this year", although this phrase is not narrowed down further in the report
www.fromthemurkydepths.co.uk/2024/06/05/new-dlr-trains-now-delayed-until-later-this-year/

My understanding is that the issues aren't related to the physical availability of the trains - all but about 11 could be in London now if they were all built (stabling space being the issue with those 11). The issue is that mechanical and/or software problems mean that has not been verified they are safe and ready to operate. It is unlikely that staff training can begin before the issues are resolved and testing has been completed, and public service definitely cannot begin before testing is complete.

Earlier today I had a little chat today with a DLR PSA.

Anyway, yes there are B23 trains here - but we knew that. He reckons it could be 2025 before they start carrying passengers. So far even the staff trainers have not been trained on them!

What was not discussed is the reason for the delay. I felt that it was better to not ask and he did not volunteer any information.

Alas, the days when new rolling stock arrived on Monday morning and was carrying passengers the same afternoon are long past.