Signal approaching Grange Hill

Three aspect signals are fairly common place on the Central line with Red, White, and Green aspects permitting various modes of Automatic, Semi-Automatic and Manual Train Operation.

Just beyond Grange Hill (Outer Rail Direction) are 9300 points (Outer Rail) and 9307 (Inner Rail) which give access to/from Hainault depot.

Signal GRH9262 does indeed have a Remote Secure Aspect.

I'm not precisely sure why it's necessary at this location, but the only plausible cause is 9300 points which are presumably in the overlap.

On the Central line manual driving is encouraged in the open sections on Sundays. This is so that the drivers maintain their manual driving skills. They are still expected to use ATO in the tunnel sections.



+1. The points are close to the starter and are included in the overlap. Therefore they are in the limit of control for the home signal.

There are no preliminary (repeater) route indicators on the Central line. The only repeaters of any sort on the Central are for Rail Gap Indicators (RGIs).

You're right, I was spewing utter gibberish there, the kind I was thinking is almost exclusively found on NR, have no idea why I though this somehow linked to the Central!

Rather than "encouraged" on Sundays and Bank Holidays drivers on the Central Line are required to operate in Coded Manual west of White City and east of Leytonstone, if we don't then occasionally Wood Lane control centre will remind us that is what we're supposed to be doing.

At other times we are required to stay in Automatic whenever possible, there was a flurry of posters a couple of years ago reminding us of this so I guess too many drivers were going Coded Manual for management's liking

I seem to recall it may be easier to drive in Coded Manual on the Central line ATC system without losing time or having other troubles than it is to drive in Protected Manual on the Jubilee/Northern ATC system. Any practitioners like to build on that?

On the central line, when would the route secure indicator light up?

Would it only light up if the route has been physically secured in some way, e.g. clip and scotch?

Would somebody have to press a button manually to make it light up?

I am sorry if I am asking a stupid question...

Would the purpose be to prevent a set of points from moving if a train was over them? Surely that couldn't happen anyway, e.g. even under ordinary circumstances ATO in the rain might cause a train to stop over a set of points due to the unreliability of ATO in poor rail adhesion conditions, and the train is just restarted? (I am asking from the perspective of a complete amateur but curious passenger...)

IIRC it was because in ATO there's no OPO alarm, therefore with multiple stations closed the train would just continue on and on.

It's for this reason that the "drag & drop" feature of the TBTC system isn't allowed to be used for more than one station at a time. It's a command used on the system where a train is taken off its timetable, and the signaller simply clicks on the train and then drags the mouse to the place where he wants it to go. The train will then run non-stop, including through platforms. To be fair, I've had it done a few times on the proviso that the train remains in PM, but off the top of my head I don't think there's a rule which specifically allows this (although there isn't one which prohibits it either!). Some very quick overnight runs from one end of the line to the other are possible this way.

Yes and no.

Whilst the Central Line system is undoubtedly better, in reality it's more a case that the biggest issue is simply that driving on the ATO lines requires driving in a certain way, and some people adapt better to this than others. Firstly there is a requirement to focus more on the speedometer, both in terms of identifying what the target speed is, and then complying with it. Secondly you will then be needing to drive the train quite hard, so chasing speed more aggressively than you would on a conventional line, and generally being prepared to use full motoring and full braking often. On the Northern this means coming into platforms and being prepared to be using pretty much full braking for most of the length of the platform. Again, some people are more comfortable with this than others. Meanwhile some people simply don't like being told what speed to drive at.

The issues with the Jubilee/Northern are as follows:

1) As well as supervising speed, the system also supervises braking curves, which means the system is breathing down your back a lot more. On the Central as long as you're doing the right speed in the right place you are left alone to do your own thing.

2) To add to (1), it doesn't help that the brake rates vary in different locations. All open sections are set to a very light rate of braking, which even the slowest drivers find too light. Meanwhile tunnel sections normally use a much heavier rate of braking, however lighter rates of braking are set in different locations for various reasons. Needless to say there's nothing to tell you what applies where, so the only way you know is through experience - and of course it doesn't help that software drops happen from time to time which can change things. Furthermore, no one has actually trained drivers on all this, so most people don't actually know the subtle differences that occur from place to place, let alone why they exist.

3) On the Central if you have an overspeed the system will simply EB the train down to the correct speed. With TBTC it will insist on bringing the train to a stand.

4) Unfortunately, (3) then increases the likelihood of the great Seltrac design flaw cropping up, which is namely that a train experiencing wheelslide is likely to become non-communicating. This then requires the train to be re-entered into the system, which can take anything up to about 10 minutes depending on location. There's then the possibility the driver might be held accountable for that delay.

5) On top of all this, TBTC - and especially the Northern - is littered with issues and glitches all over the place, where the system behaves in ways it simply shouldn't. There are places where the target speed can start dropping with zero warning, in which case if you're driving on the limit then you are very likely to get an overspeed. A favourite for this seems to be if you catch up with the train in front and the location coincides with change in permanent speed restriction - the system gives warning of the latter but completely ignores the former. So, for example, at places like Clapham Common NB, Bank NB, Euston CX SB, Euston City SB, Borough SB, Charing Cross SB, to name but a few which spring to mind, you've basically got to make an educated guess as to whether you are likely to have caught up with the train in front, and if you think the answer to that is yes then drive 5-10 mph under at the places concerned. Get it wrong and you will get EB'd, although in the tunnel this is very unlikely to result in the train going NCT. There are also loads and loads of spurious downward chimes which pop up momentarily, which you have to ignore, although of course if you get used to ignoring then the one time you get a real one and don't react then you might get EB'd.]

6) Finally, if driving on the limit then you will get loads and loads of "Over Speed Imminent" warnings on the TOD, all accompanied by warning beeps played loudly in the cab. These even occur if you're on target speed and coasting on an uphill gradient. It's not uncommon to have something like 10 to 20 of these warnings pop up on each station-to-station run. The regular PM drivers find their brain tunes out in the same way drivers do to the half-hourly service update messages, but get a visitor in the cab and they find the tones extremely annoying!

By contrast, the Central Line has none of this nonsense. The only real risk is that some of the signals aren't wonderfully sited. There's a particularly nasty one approaching North Acton WB where the signal is on a left-hand curve with a retaining wall to the left. It's simply a case that if you get a zero target speed then one needs to drop to walking pace unless the signal or BMB is already clearly visible. Obviously one also needs to religiously check starting signals just like on a conventional line. Apart from that there's little to catch you out on the Central.

Despite all the issues with TBTC, driving around in PM can be a pleasurable experience once one is used to it - as it does have one good feature, namely that it's possible to drive around like a bat out of hell without there being much risk of making an error with consequences attached (e.g. a SPAD). I think most people would still prefer to return to signals though!

Could it not also be used in lieu of manually securing points in the event of a track circuit failure or some other failure preventing a proceed aspect from being displayed?

Could someone tell me what it means to be 'EBd' please?

Exactly - it was originally an HMRI requirement for deep-level One Person Operation, allowing a second train to rapidly draw up to the one ahead whose driver was in trouble. In practice it was found to be very useful in working around track circuit failures which is what it is most often used for.

Although to be pedantic the "lever" exists only in the brain of the WESTRACE interlocking computer at GRH. The N (& V) style frames are and were a thing of beauty! I can't remember whether the original interlocking at GRH was a slave frame operated from HAI, a la Harrow or whether there was just 1 frame covering all of HAI & GRH, IIRC the cabin was adjacent to the HAI entrance to the depot.