Issues with Northern line TBTC

You make them sound like Micro$oft... (actually, like a great many vendors these days)

It amazes me that organizations will set up things like this- let's get everyone together to watch the new system fall over. I do hope nobody dresses you down for doing what they said.

A lot of the trouble is that technically they have delivered what they were contractually required to do so. My own view is LU lacks the expertise to identify and/or challenge issues, which then makes it hard to chase up. It’s ridiculous that consultants have been brought on board to progress issues on the Jubilee and Northern. The Thales attitude seems to be very lackadaisical - “send it over to us and we’ll have a look when we can be bothered”.

The worst issue is brake rate in the open (and many tunnel locations too) which causes time to be lost and is one of the reasons trains fail to arrive on time at Barnet and Edgware. There seems to be no resolution to this.

There’s still loads of software issues where the system doesn’t behave as it should, and a list of operating restrictions as long as your arm to go with those which are known. New issues still get found from time to time.

Finally th PM driving experience is still poor, again with many behaviours and issues which shouldn’t happen. In practice this leads to poor driver confidence, which means many drivers lose time when in PM, which contributes to late running when it has to be done for any reason. An issue in PM is also likely to be an undesirable behaviour when in ATO.

The Northern may appear okay when everything is running fine, but all these issues make their presence very known when the job is up the wall. Look at the day when platform 5 was out of commission at Golders Green and everything had to run through the middle - by the afternoon the service was running over an hour late - mainly due to poor TBTC behaviour than any other reason. Or see how much blocking back occurs through Camden when the service is running late, the system seems incapable of pushing trains through efficiently - for example if a train is leaving platform 2 the following train won’t start to enter the platform until the preceding train is well clear of the points. Or how trains still get a pointless stop between Golders Green and Hampstead under certain conditions.

I guess there comes a point in the contract where both parties have to agree the contract has come to an end, presumably having reached a point where it was capable of delivering a certain level of service. LU for their part simply don't have the urge or expertise to challenge, and in my view there's various reasons for that. There are now consultants involved, and I bet that's not coming cheap.

I'm not getting my hopes up with regards to these, "consultants", just after Thales got the botched SSR Upgrade contract, it emerged that TFL employed (and perhaps still does employ) consultants whom as it turned out were also working for Thales. Network Rail also have digital railway consultants whom are also part of Thales.

Seems like a very unhealthy relationship between operator and contractor which means challenging the aforementioned issues is unheard of in some departments whom still believe it's job done with regards to the Northern line.

Well the 96 stock already seems to be falling apart now thanks to TBTC, so the 95 stock probably won't be far behind if they start running them at 60mph.
A lot of people praise TBTC but imo it isn't a very good way of signalling a tube line.

The best ATO system is still the Central line one. It recovers quickly, does a good job keeping trains to time and what also makes it far better is the fact that unlike TBTC, it keeps trains moving not holding them close together in a queue; Yes I know sometimes you can see a train ahead on the Central, but there is less likelyhood of stopping as the trains are kept further apart. As a passenger I would rather be moving not sitting in a tunnel every 30 seconds because of a train 1m in front of me.

TBTC can run a lot of trains but what good is it when they just keep sitting in tunnels when there are too many trains on the line.


Central line Ato - Gets you from A to B asap
TBTC - Can hold a lot more trains in a queue.

I know which I prefer.


Keeping this post in line with the subject though, I remember when the Northern was manually driven and the train would pull out of Euston City NB and accelerate to about 20/25mph. Obviously because of Camden being ahead trains could be held outside and occasionally the train would stop at a signal. However most of the time a good manual driver would drive at the perfect speed to give time for the signal ahead to clear and the train would go straight in to Camden platform.

Since TBTC every time I have used the line around that section, the train accelerates to the full permitted speed only to then slow down and be held at the signal... How is this an improvement?!

The Northern Line was once the misery line. With very old signals and very old trains. It's not perfect, but its better than it was (in terms of frequency and reliability) than 20 years ago.

Could any of the reliability issues be due to the budget on which it was installed? Negotiating the cheapest contract possible. For example, I am guessing that the option for bidirectional running would have been more expensive, so wasn't procured, but may have been useful to recover from a problem?

Both are good systems, DTG-R was an evolution of Westinghouse's previous products and experience. Both are essentially fixed block, DTG-R differing from the previous generation in that the system is brake assured therefore calculated overlaps are not required, just a nominal (50m) safety distance which allows the train to draw up to the marker boards.

People shouldn’t really be hanging back in that way. If the train is early (although how would the driver know for sure without having a copy of the WTT in front of them) then it’s acceptable to coast a bit, but generally under signals green means drive at line speed and that’s what the driver is expected to do. Yes it’s possible to adjust speed to avoid stopping, but do this too much and it simply messes up line capacity. Having said that there are a couple of places where it’s undesirable to come to a stand in PM - as due to gradient and enforced brake rate there’s a risk of rolling back - it’s very hard to get a smooth stop and avoid a roll back, so best to try not to stop.

Agree with Simon here. I *hate* the way the Northern line is set up now; it really is "on/off" and it's noticeable. When in manual the t/ops were able to coast then gently apply power to maintain speed as necessary; the new system seems to be completely unable to do this. As someone who is somewhat mechanically minded, I can see how this would impact the trains much harder - more wear on components, especially bushes and suspension components that take the brunt of the constant changes in power delivery. Certainly if I drove my car the way the computers drive the trains, I would expect to wear through engine mounts and suspension components at a much higher rate! From a passenger perspective, I don't usually get travel sick; it's very rare. However there have been a few times on the Northern line when I've felt decidedly "off". Never happens on the Vic or Central, both of which seem to have far superior systems.

This idea of it killing the trains is a bit of a misnomer - modern trains don’t really have a problem with being driven in an on/off manner, although it has certainly caused an issue with irregular wear on the 95 stock brake blocks, which is the main reason 60mph running hasn’t yet been achieved. 95 stock has always responded well to being driven quite aggressively, and there hasn’t been a noticeable dip in reliability since ATO came in, in fact I’d say if anything it’s a little better. 95 stock does have a big advantage over 96 stock in that there’s a few more spare trains each day.

In some ways the trains are simply a little high performance for the Northern, which is a torturous alignment compared to some other lines. Even in PM it’s hard to avoid an on/off driving style. There are areas where the TBTC could do better however, especially nonsense like the velocity ceiling when running early.