Northern line driver's eye view

Tehe I was thinking more in terms of signage and RS1, RS2, etc. and stuff!

Okay thanks So what is it one sees in the cab?

CTN (the location) is Camden Town? And MOR-Y (the destination) is Morden via Bank?

The 95s have a new screen just like the 96s, the screen you see in the picture replaces the old-fashioned speed indicator, I believe the screen on the left is the TOD (Train Operator Display) which works pretty much as it did before, although it now obviously displays all kinds of TBTC related info as well and the one on the right remains for CCTV. I think both screens on the 96s are for CCTV aren't they?

Thanks everyone, so when the train is on the move, what is displayed? I've seen pictures with a blue rounded rectangle with a distance in it where the dwell time countdown is in the above picture and an image of a speed limit sign like you have on a road or much of national rail (white disk with red border showing speed in black text) where the AS is. But I obviously don't really know what one is meant to do with this information.

So you'd be driving along and the red bar in tridentalx's picture would be at - let's say 50. That's to say that the end of the red bar - where it rises in height - would be here at 50, of course, and then the rest of the red bar would continue to the end of the display. And you'd also have a yellow bar indicating your current speed, right? This (the end of it) must be at or before the red bar, right? If it gets too close, the bells and whistles dom mentioned go off, I take it?

Would you have a distance until target speed is required in this case, where there's a steady target speed? When is the change in target speed transmitted to the train and when is it displayed to the operator?

Leaving that aside, let's continue. All is well in the life of you until you hear - let's say - a falling tone and a new target speed is displayed where the AS is in the picture. Let's say, as you have, the new target speed is 20. The distance until target speed is required will start to decrease as the train nears the point where the new target speed is required, am I right? As it decreases, does the red bar creep down, guiding the deceleration of the train, or does it stay at 50 until the distance reaches 0 and then immediately drop all the way down to 20? In other words, is the rate of deceleration at the T/Op's discretion, or is it guided by the TBTC?

When a train stops in a station, does the target speed drop to 0 for the station stop, guiding the train to the correct stopping mark, or does it stay at the appropriate speed - like on the Central - and leave the actual stopping to the operator or to the ATO (which has a map on the Central, as I understand it)? Do you still have the stopping boards on the platforms?

And a correction to my earlier post, based on what proji has said. Dom: The screen shown in tridentalx's picture is apparently the TOD. The left hand screen in the middle remains the screen for the *TMS (Train Management System). I was confused - I thought that TOD was actually the name of this, older screen, displaying various information and warnings - as it always did, but now with TBTC-related info presumably also displayed. In fact, TOD seems to be the name of the new, retrofitted TBTC screen displaying what we've been talking about and replacing the old-style speedo

Basically, the TOD will show a target speed, which the Train Operator should aim to achieve. As you approach this speed there will be persistent 'Overspeed imminent' warnings, I can't recall off the top of my head the exact design but I think it's something along the lines of if the VOBC predicts you are within 3 seconds of exceeding the maximum safe speed. Likewise, if there is a new lower target speed the target speed will drop accompanied by a downward-sounding chime, then soon after the 'hand' will start coming down, and the Train Operator should ideally match their braking so that the actual speed is more or less in line with the hand. If braking to a stand, or if there are a number of speed restrictions close together (as I understand), the TOD will instead show a down arrow instead of a speed. When the down arrow appears generally you aim to stop, here the distance comes in to play as this will progressively count down to 0m. The driver should stop on 0m or 1m. Stopping on more than this can cause all sorts of issues in some places!

From a realistic point of view, basically there are two ways to drive. You can either match the target speed exactly (and it *is* possible, especially if you know the gradients!) and have to endure 'overspeed immiment' warnings every few seconds, or go just below it and get a more peaceful journey - but lose a few seconds in each section. When the target speed drops, I normally tend to ignore it until a few seconds later the 'overspeed immiment' alarm sounds, then brake down to the new speed. In the tunnel sections this will require fairly heavy braking (just like the ATO), in the open sections the brake rate is more gently so generally lighter braking is adequate. With experience, it is more than possible to brake almost exactly to the hand, and drive in PM as quick or even very slightly quicker than the ATO does.

The reason it can be quicker in PM is that the ATO has a messy habit of overbraking for speed restrictions, particularly when going uphill. So if for example braking from 35 mph to 25 mph, the ATO tends to go down to about 21-22 mph, then wait a couple of seconds and then motor back up to 25 mph. An experienced driver can get it down to 25 mph spot on.

All that is the theory. In reality, PM driving is not a particularly user-friendly experience. It's not uncommon for the target speed to drop with no warning (leading to the VOBC detecting a speed violation and applying the emergency brake), and the variety of brake rates used in different locations means the driver has to keep on his toes to avoid speed violations. No one yet seems to have provided a convincing explanation for these occasions when the target speed drops with no warning, there are still issues with the system which are being ironed out - my understanding is that PM issues are generally not the top priority. Speed violations are not uncommon in PM, with the way the system is performing at present if you aim to match the target speed exactly then you will get a speed violation from time to time. It's not a big deal if it does happen, as the train can normally be got moving again immediately - though it's undesirable as it results in a sharp stop for the passengers.

Initially the driver has to keep a very close eye on the TOD, which can be unnerving finding little time is spent looking out at the line ahead, however with time and experience reliance on the TOD becomes less - however even this can be problematic as you can spend a month getting used to the system behaving in a certain way, then a new speed restriction or software drop comes along and suddenly the speed or braking has changed without notice! The Central Line system is a million times better in many respects.