What’s in a name? ‘Driverless’, it seems

During early October I visited the small display about the design of the new deep tube rolling stock that London Underground had put on view in the spacious north ticket hall at King’s Cross. It was interesting enough, for a design at such a formative stage and which has not yet been tendered to the train manufacturers who might (for practical reasons) have their own ideas. Most of the intended features had previously been aired in the press so, in truth, the amount of new information was not great, but it was interesting to study the many visuals at leisure. In any case, the display was not intended for the technical press so much as Piccadilly Line passengers, who, if all goes to plan, will be the first to sample the new trains.

Just to get the details out of the way, it is proposed to form up the trains from relatively short carriages which will reduce platform gaps that would otherwise occur, there may be nine or ten such carriages, producing a train a little longer than a 1973-stock that will occupy the whole of the platform area. Intermediate carriages will share ‘bogies’ (LU technical people call them trucks) with neighbouring carriages, so that (say) ten carriages would have just eleven trucks, compared with the present six carriages having twelve. This not only reduces weight substantially, but provides more room under the car bodies for equipment. It also makes it easier to provide through connections between all cars (like the S stock), making the train interior continuous.



The reduction in weight, caused by clever design and modern materials, means that the new trains will use usefully less energy than the 1973 stock. The LU thinking had been to re-invest this saving into providing air-cooling of the car interiors, meeting a perceived demand to make trains running through central London cooler, especially in summer. Unfortunately the huge growth in tube traffic means that a much more intensive service will be needed by the time the new trains enter service, so that total energy usage will unavoidably rise – increasing, not reducing, heat input to an already over-warm system. It is therefore recognized now that improvements to LU’s tunnel ventilation systems will still be necessary if the tunnels are not to warm up further, and the ‘energy balance’ equation doesn’t address the concerns of anyone who feels that the existing station temperatures are already much too high.

It can be hard to understand why the ‘simple’ issue of train cooling is constantly referred to as ‘challenging’ when most other metros are cheerfully addressing the issue or thinking about it. Unfortunately it is a basic rule of physics that this ‘low grade’ heat energy can only really be pumped around, and if you try and chill the temperature inside the train the only place you can pump the heat is to a point outside the train, raising the tunnel temperature. More importantly, it raises the air temperature in the narrow annulus between the train and the tube tunnel rings; this is not a problem when the train is moving and there is a huge passing airflow, but it gets quite interesting if a train becomes stationary for any length of time. First the very warm and perhaps static external air gets progressively less able to accept the pumped heat (reducing in-carriage cooling effect when perhaps it is most wanted) and then it will want to leak back inside the train in some form, so the carriages need good sealing at a time where on older trains people would already have opened all the windows, and older trains were notably leaky anyway. We then have to consider what would happen in the event of a major power failure stranding sealed trains in tunnels – there are of course a whole range of things that could be done to mitigate such risks, and which are being looked at, but the only point I want to make here is that ‘simple’ it isn’t, at least in 12ft bore deep tube tunnels (another reason for not persisting with them indefinitely – see my last blog item).

We must then consider that the equipment can be quite bulky. On a normal train the air cooling (or even more bulky air-conditioning) equipment goes in the roof, next to the air ducting used to distribute conditioned air where it is needed. This is quite impossible in the deep tube where passengers are already banging their heads against an equipment-free roof. The reduction in trucks deployed does increase the space under car floors though, so it will have to go here. It will almost certainly mean rejected heat will be dissipated from beneath the train.

What did strike me about the display was the carefully crafted set of words used to describe the future of train drivers. I must start by saying it is the intention for the new trains to be delivered with a driving cab at each end, but to make the cab ‘demountable’ so it can be converted to passenger space in the event that it is decided no longer to have a member of staff in a driving cab (not something likely any time soon, as I have observed elsewhere).


The display made the quite proper observation that the new trains will be introduced ‘from the early 2020s’ [six or seven years hence seems a long time given tenders are being prepared now] and last for forty years or so, so the design should be future-proofed – they will last till at least 2060. So far so good – wish this had happened with some of our older stock.

The future-proofing message explained: ‘… this also means having trains that could one day be used in fully-automated mode. We would only consider implementing such a step following extensive engagement with our customers, stakeholders, staff and trade unions.’ The message continues: ‘TfL is committed to having a fully-staffed Tube network, on hand to assist customers and ensure safe operations.’ And then: ‘Given our existing train fleets, all drivers currently working at London Underground will be able to continue to drive trains for the rest of their careers’. It will be noted that though thrown together to imply some connection, these statements are each quite independent of each other and do not say that trains will remain fully staffed indefinitely. Options are obviously being kept open (and in any case what transport professional would be daft enough today to make a definite statement about what might be seen as desirable some thirty years away?).

Now, what to make of this. What I pick up on is the expression ‘fully-automated mode’, which isn’t explained and leaves certain questions (understandably) hanging. Whatever it is, though, seems to mean that a driving cab is not necessary. In that context, what does fully-staffed tube network mean? If it means a member of staff on every [Piccadilly Line] train it doesn’t actually say so.

The press (oh dear) found the display of sufficient interest to report about, though seemed to have difficulty with writing connected statements themselves. Many of the papers took the angle that ‘driverless’ trains were on the way, as though they were imminent and in some why connected with a threatened ‘tube’ strike which in the event didn’t happen and was nothing in any way connected with train operations. The word ‘driverless’ did not appear at the exhibition, by the way and is a word the press seems to have latched onto without having any real idea what they are talking about.

Perhaps I could offer up the actual options that are open to LU, based on a slightly academic concept called Grade of Automation (or Goa).

GOA 1 means a manually driven system with some kind of automatic train protection (rather like traditional Underground).

GOA 2 means what is now called a semi-automatic system with an operator in the cab operating the doors and providing a start signal, the train driving automatically between stations. This is akin to the operation on Victoria, Central, Jubilee and Northern Lines.

GOA 3 means a fully automatic system with no need for a conventional driving cab and with the operator able to move around the train (usually, but not necessarily on every system, operating the doors and providing assistance). This is akin to the system on Docklands Light Railway.

GOA 4 means a fully automatic system without the necessity for any member of staff on board; it is sometimes called Unattended Train Operation of UTO.

Needless to say, each Goa level requires successively more sophisticated and reliable equipment that must address progressively more challenging tasks. It is accepted by transport professionals that the challenges of Goa 4 mean that because emergencies can arise (not all of which can be foreseen) staff must either be able to get to a stranded train very quickly or provide for a train being driven by remote control. In the deep tube getting to a train ‘quickly’ can be very difficult and some failures will inevitably occur where a train cannot be driven at all.

Goa 4 must perhaps be a very long term goal, but nobody yet has the answers to how to achieve this in the deep tube and quite rightly are not committing to anything that cannot at present be done (though this does not stop the politicos from mouthing vague threats about it).

So in that context, what might ‘driverless’ mean? The four lines already operating to Goa 2 are ‘driverless’ in that the train operators do not ‘drive’ in ordinary passenger service, yet Goa 4 (in the deep tube) is manifestly unachievable for at least 15 years and I suspect rather longer.

That brings us to Goa 3 then? Well I have been told by senior staff that LU has already considered Goa 3 and for exactly the same reasons I set out in my Modern Railways article on ‘driverless’ trains concluded that it isn’t really practicable in today’s busy deep tube network. I have seen odd references by LU to this form of operation, but I do not give them much credibility. In fairness, one can conceive that the more obvious practical problem of train despatch might be achievable in Goa 3 if it were managed from the platform rather than from the train, but this has its own problems and doesn’t get away from some of the other shortcomings of cabless Goa 3 in a crowded deep level tube (and does not necessarily save much cost). I’ll believe this is the approach only when I see it.

The problem with the word ‘driverless’ is that is has newspaper appeal, even if nobody knows what it means. We can hardly expect the papers leaping to explain Goa levels either – so the industry really needs to come up with some appealing terminology itself. As it happens ‘Unattended Train Operation’ is fairly self explanatory, and is the level likely to cause the most concern, upset or savings, depending on who it is being asked about it. 

That leaves us with the need to think of terms for Goa 2 where perhaps the term semi-automatic operation is descriptive enough. Goa 3 appears to be the problem area for a decent term, perhaps calling for something like mobile train operator operation or the like. I’m sure someone else can do better than these though.


This graphic of a doorway on one of the new trains shows level access (not done on the Victoria Line, requiring platform humps). We do not yet know if this implies narrower trains in order to achieve this, but if platform edge doors are in mind for Goa 4 operation then it is easier if trains are ‘level’ – but as we’ve found on S stock can increase gaps on curves. Another issue that needs a long term fix. Implications for door height I do not yet know.

In any event, the problems of maximizing automation in the deep tube and keeping the public and safety authorities on side are surely magnified by the need to operate trains in 12ft diameter tunnels, warming to an earlier theme. It would be good to think that by the time these ‘new tube for London’ trains are ripe for replacement our successors will have more space to work with.

If you want to know more about the complications of bringing these new trains into service, then click HERE. Meanwhile I note that the London Infrastructure Plan 2050 is quoting the following dates for Goa 4 operation (and note Goa 3 isn’t mentioned): Piccadilly 2029, Central 2032. Silence for the rest. 


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About machorne

I have always lived in London and taken a great interest in its history and ongoing development. This extended into the history of its transport services, about which I have written a number of books - I have spent most of my working life working in the industry and observing changes from within, mostly to the good, but not always so. I continue to write, and have a website with half finished stuff in it so that it is at least available, if not complete. Several new books are in hand. I have many 'works in progress' and some of these can be found on my website; the we address is http://www.metadyne.co.uk
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