NB signals covered up for testing

Just a guess, but surely if your train passes a red aspect on a signal relating to the line you are travelling on, it's a SPAD?

The whole line is shut for ATO testing 2-5th April. The tripcocks are being cut out, have seen a few trains go through reds. In this instance they wouldnt be classified as SPADS, and they would have prior approval.

AFAIK its ATO.

Thanks for that

I notice that the signals are covered up again today and I enjoyed watching a train with its tripcock cut out accelerate away through the raised trainstop for the Finchley Rd SB starter....

I hope no-one minds me asking - how has the testing been going this weekend compared to back in April?

How much of the line is able to be run under ATO these days?

If I might chuck in a few comments about this:

ATO - automatic driving that is - does improve performance and allows more trains to be run over a manual system, even if nothing else changes. For example, if you improve the braking rate into stations by just 0.1m/s/s, you can get an extra train per hour through the line. The average driver, driving manually, won't get much better than 0.7m/s/s, whereas a modern train on ATO will get 1m/s/s. Even the 67TS gets 0.9m/s/s and a smooth stop with the new NADB.

You are right to be concerned about terminal operation. Brixton is the pinch point on the Victoria Line and effectively restricts the throughput to 28.5 trains per hour. Having an efficient point layout with sectional release is essential. Dwell time at busy stations will also restrict throughput. Any more than 40s wheel stop to wheel start is death to a 2 minute headway.

As for moving block, I would question the assertion that the Thales S40 system is true moving block. If you have a system with a fixed, track-based loop, crossing every 25 metres to provide location updates, it's hardly moving, is it? It's more like "very short fixed block". Leaving that argument aside, it is a mature system though. It's been around for over 20 years in one form or another and it works. The problem is that its previous installations have almost always been on new railways, not overlays as they're doing on LU. That's where the trouble lies - trying to put new wine into old bottles.

Stepping back is indeed effective, but when something goes wrong and trains come in the wrong order you have a problem - imagine the driver that's supposed to take your train is behind you, and can't come in to the station because both platforms are taken.

Points at Stratford are air operated

It will all revolve around the magic 4 minutes - in/out/shake-it-all-about, terminal stand time cannot be directly compared between the Vic. and the Jubilee; of course these days you've got to factor in the sloooooooow electric points too![/quote]

What you are describing is stepping back, which already takes place on the Victoria Line. The dwell times at Brixton are still restricted by the crossover (i.e a train in the SB platform has to wait for a train to depart and arrive in the NB platform before it can depart.)

Your opinions of Thales S40 seem very negative. It is the most mature and commercially successful "moving block" signalling system available. Moving block signalling can have platform re-occupation times approx 10-20 secs better than fixed block ATO signalling - thats quite a few extra tph! Paris Line 14 (Siemens moving block) has platform re-occupation times of 40secs!

would you rather have a system that is adequate for now or one that has the capacity required for the foreseeable future? If you choose option 1 then you must accept further disruption as the system is replaced within a decade.
It isn't just about which is cheapest but which gives the best value over the lifetime of the assets.