Northern line TBTC

Know it's early fays yet, but does anyone know when NMA3 is scheduled to be completed?

Am guessing it would be a more protracted delivery stage due to junctions around Camden and Euston.

I went on my first trip on the Northern Line for a long while and I was distinctly unimpressed with the ATO. The TO had to drive manually from MHE to Finchley Central for some reason (about 3pm yesterday) and then the journey from Finchley Central to Highgate was a series of acceleration, coasting, braking, coasting, acceleration etc etc.

Coming back the other way was just as bad. Highgate to East Finchley bearing in mind the gradient was the same pattern of go, coast, slow, go again. We came out of the tunnel at a rate of knots, probably faster than manual driving. Leaving Finchley Central for Mill Hill East, we accelerated and then slowed to a crawl over the points and then took off again! Hopefully this can be smoothed out in time.

Well just been on the ITV news looks like problems with TBTC already www.itv.com/news/london/story/2013-07-10/head-on-tube-collision-avoided-says-rmt/ or was they testing to see how close they can really get

The RTM are wrong on this.

Remember that Seltrac is inherently a bi-directional system - for example the DLR is fully bi-directional.

This capability was not provided on London Underground because under the old signalling most points were only designed to be locked in the normal direction of travel. Adding this locking would have incurred additional cost for little operational gain.

However the Mill Hill East branch was always bi-directional, and this capability was simply carried over into the new signalling.

Like all technology, this additional capability is only as clever as the human operating it. The system would have issued an "are you sure?" type message before routing a second train on to the branch.

The separation of trains is then under the control of the Seltrac Vehicle Control Centre. I am sure the signaller intervened because he realised the situation was now going to be inconvenient, however had the second train been left to run then it would simply have been safely brought to a stand, under normal braking, a safe distance from the first train. It would then have been a simple case of signalling the second train back to Finchley Central.

If one looks at Chalfont & Latimer, the same situation is provided for under conventional signalling. If a train is already on the Chesham branch, a second train can be signalled onto the branch as far as signal J.T.83 (for example to reverse back into the bay road). This would happen for example if the shuttle train needed to be changed over. This is basically the same setup as at Mill Hill East now, except that under Seltrac the system is not bound by the position of fixed signals.

No. They were hoping to get it going a couple of weekends ago and apparently testing went well but the necessary (large amount) of paperwork wasn't signed off so it wasn't able to go live. Apparently the next date is 26th October.

I see virtually the entire line is closed this weekend - more TBTC testing?

Why do they need to close so much of the line? If it is for TBTC testing, couldn't they just detrain at Angel/Mornington Crescent as per last time?

Apparently it did indeed go live - the main difference was that it's said each train came into stations much much quicker.

Highgate – Euston (charing cross) and Angel was the plan I saw in another thread. I took a ride this morning and the train absolutely flew along from camden to Angel, ride seemed a bit smoother than it has been from Highgate to Finchley Central too. I guess they are gradually fixing the gremlins. Looking forward to whole line going live and new timetable next year!

So far so good. Very few problems in the first two days except for some adhesion issues today probably due to the stormy weather bringing down more leaves.

Under TBTC, the train does seem to brake and accelerate in some rather inexplicable places. For example, upon leaving Angel northbound, it accelerates up to around 20mph, then seems to hold that speed for some time before accelerating. I'm not aware that there is a TSR in place at that location, so what is the reason for this? As others have mentioned, the trains enter the platform at a higher speed, and some of the inter station runs are quite speedy.

I'm assuming that the system is not yet running under full capacity in order to keep the trains to the current timetable. I remember when they istalled ATO on the Central, it caused a problem because the trains were running ridiculously early when they rolled out ATO section by section on the (then) pre ATO timetable. Central line ATO, unlike TBTC, doesn't have the ability to tailor the train's speed to match the timetable. If it has a proceed code, it will drive at the maximum permitted speed for that location.

Is there a target for NMA4 to go live yet?

As far as I know NMA4 is planned to go live in January time and apparently the project as a whole is about six months ahead of schedule at the moment. Camden junction seems to have gone fairly smoothly, the hardest is Golders area, which they're leaving until last. 

This weekend test trains are working between Morden and north of Stockwell. These trains will be running empty. No passenger trains are running on the line between Kennington and Morden.