What of the differences between LU’s network and NR’s?
“The basic laws of physics and electronics still apply. The big difference is that you’ve got mixed fleets, whereas on the Underground it’s largely a captive fleet on a given line, with some notable exceptions. The sub-surface lines are more challenging because you have Met, Jubilee and Picc running. You have Triangle Junction, which I think is one of the busiest junctions in the world - that’s Aldgate way with 1,400 train movements a day. TfL is having to face some very complex junctions.
“On the Northern Line: everybody was dead scared about some locations, specifically Kennington and Camden - they are difficult junctions - high-capacity, very difficult junctions, but it shows DR can work on difficult junctions. The Jubilee Line has shown it can work with screen doors and lots of different other applications, junctions and sidings - Wembley, Stanmore, at Stratford, for example.
“You know, these are complex layouts, so it shows it can work with that. It shows it can work with massive capacity and lots of people, lots of issues and high passenger demand. It also shows that you need to harmonise this with the operating ‘spec’. It shows you have to link in to how you manage stations, dwell times, how you manage your staff and how you turn trains round in terminal stations. All that is positive experience, but the big difference with the main line is the mixed traffic.”
Waboso’s summary neatly and effectively counters the common - and rather dismissive - view that LU lines are simple when compared with main lines. Yes, the Victoria Line might be essentially only a twin-track railway with crossovers at each end and a uniform fleet of trains. But those trains pause only a few minutes at their termini before reversing. The trick for the main line railway will be to improve capacity and turn-round times at termini and capacity through junctions, to ensure the benefits of the easier job of running more trains over sections of plain line are not lost in delays at those termini and junctions. The pay-off for DR is getting to this potential nirvana from where our railway is right now.
Waboso: “The end-state is always fantastic, how you get there in a very busy operational railway is the challenge. So the migration would probably be: do you first create shorter blocks as part of your resignalling, buy your trains with ERTMS fitted, overlay ETCS, and put your block marker boards down for your shorter signals that then benefit the fitted trains, because they have computers and can take advantage of that, while the unfitted trains are still driven and controlled according to lineside signal indications.
“So you’re not getting a disbenefit for the unfitted trains, but you are getting a benefit for the fitted trains. Then, at some point, when you equip enough trains (and I always have these two dials in my head - the infrastructure dial and the trains dial), you are able to take the decision to remove the signals. You’ve already invested in the shorter tracks , so they never come out.
“So you move from full digital benefit for fitted trains to benefit for ALL trains. And the price for that is to equip all trains. So that’s an option for track and train rollout but at that point, as well as benefit for all trains, you get ‘opex’ savings because you also take down all signals. So, it’s more an incremental benefits realisation.
“Now, what I’m saying is that that gives you a lot of the benefit of Level 3 because you’ve started to reduce your infrastructure. But it’s true to say that you still have to detect the shorter blocks. You have to put in the block layout. Now, the question I’ve got is: ‘Does taking out the shorter blocks, because Level 3 does not have a block layout, give you the big benefit that is claimed?’ Because you will still need to have detection around points. There is potentially still a requirement for unfitted trains unless you are absolutely able to guarantee that absolutely all trains will be fitted.
“You have to look at the facts. You need to be careful about how you then deploy the migration strategy and understand how it’s going to work. So that’s why I’m not going to build this plan on Level 3 as a fantastic thing, because I think that Level 2 with no signals takes me a long way down the Level 3 road. The key issue is to have onwards compatibility with Level 3.
“Your specification for Level 2 must be such that you can build Level 3 on it at very small cost. You don’t want people to say ‘oh blimey, all those computers need to come out’ because it’s a big processing change. That’s probably more the trick, if I’m honest. So that’s one of the things we’re looking at.”
One major difference from LU to NR is the variety of trains running. LU has, by and large, a uniform fleet per line with very little crossover of train types. You won’t find a Northern Line train at Hainault, and a Met train is never going to appear at Southwark. The trains on each route are effectively uniform in terms of speed, acceleration, braking and so on.
It prompts a question from Waboso: “Do you fit all the trains and go to ‘no signals’ quickly? Or do you leave - as in Thameslink - an overlay solution so that you can still run unfitted trains? These are all the options that we have to look at in the forward plan.
“And you have high speed, you have 125mph. On the Tube you don’t get much beyond 60kph or 70kph . The basic rules of ‘it does work and it can work’ have been proven. The question is how you apply it to the main line.
“And so for Level 3, you get issues on the main line such as variable train lengths. So with Level 3, where you don’t have a lot of train detection, how do you manage that? What are the operating rules?
“On the Underground, the big lesson is to spend a lot of time working out what the operational rule set is, because all that is then coded into the software. You spend a lot of time marshalling all the various parties to define that and then you go for preliminary design review (PDR). It’s a big thing. This alone could take two years. You get your people and you fly them out to the software developer - because every minute spent on that is worth a thousand minutes downstream.
