ATO in the rain

When the ATO first came in on the Central Line it was terrible. Trains were over shooting stations and SPADDING signals left right and centre in the rain.
Having been modified several times, the trains now stop when they lose data.
A minor inconvenience to the driver but better in the long run.

What sarcastic dig?

The "banned for life" comment would only be sarcastic if the mods had been unnecessarily heavy handed about unexplained abbreviations - which they haven't.

Theoretically, the wheel slide protection system should prevent wheel flats.

There are no communications or waypoints between stations? I'd expect at least a few, otherwise it would kill the tph count; the train would have to expect the track is clear to the next station. (Or are there other systems that look forward and adjust speed on the fly, as it were?)

345, 346, 347, Hey! that waypoint's at 353 (...skipping mentally to 353...), 354, 355 etc

(It's also entirely possible that I don't understand the ATO system in question.)

Edit- some of my questions are touched on in the consecutive-stations-closed thread.

I believe as a counter-measure to this very problem, there is a kind of 'top up' loop midway down the platform, but there are two things going on here.

Okay so we need to differentiate the ATP, the Automatic Train Protection, from the ATO, the Automatic Train Operation.

The ATP provides the signalling information and the train protection. Coded signals are injected into the rails and picked up by a receiver on the train. These signals give the train the maximum safe speed at which the train can be driven *now* and the target speed that the train ought to be doing when it enters the next section. So you see the ATP provides this information, but it also enforces it. If the train is being driven by man or machine the ATP is comparing the actual speed against the maximum safe speed. If the maximum safe speed is exceeded, the ATP steps in and applies the emergency brake. This prevents the train from being driven in excess of the speed limit and will also bring the train to a rapid half if it goes past a red signal, or equivalent, and into a section of track which it is not permitted to enter, due to the presence of the train up ahead. The ATP is provided continuously by signal generators and is not downloaded at a station stop.

The ATO drives the train automatically. In order to do this, it needs to know things like the gradient profile of the line, the lengths of the block sections, and the distance to the next station stopping point. It needs to know the lengths of the block sections, because the ATP will tell it the target speed it should be doing on entering the next section (possibly 0 - i.e. do not enter the next section), but that's it. The ATO needs to know where the next section actually is! The human, on the other hand, can see either a block marker board, or a colour-light signal out of the window and they will have their route knowledge as well, so they will know when to expect these signs. Obviously the ATO needs to know how far the next station's stopping point is, so that it can stop in the right place at the next station - indeed, so that it can stop at the next station at all. It is this information, for the next two stations ahead, that is transmitted to the train through the PAC, for the Automatic Train Operation - so that it can drive the train automatically.

The track does not need to be clear to the next station, the ATP provides continuous coded signals to the train. Say a train is stopped ahead in track section 1100. Because the ATP can only really put the anchors on if a train passes a red signal (or equivalent), it can't prevent a train from passing the red signal (or equivalent). Therefore a following train may not enter section 1098, we need to stop it before it enters 1098. Then, if it fails to stop, it will be stopped in 1098 by the ATP, will not enter 1100 and cannot hit the train stopped ahead.

So, we want to stop a train before it enters 1098 (assuming a sequence of ... 1090 1092 1094 1096 1098 1100 1102 ...). The maximum safe speed in 1098 will be zero. That is, do not go into 1098. In 1096, the target speed on entering the next section (1098) will be 0, i.e. don't enter the next section. The maximum safe speed for 1096 will be, say, 15. In 1094, the target speed on entering the next section (1096) will be 15, the maximum safe speed will be, say, 35. In 1092, the target speed on entering the next section will be 35, the maximum safe speed will be, say, 55. In 1090, the target speed on entering the next section will be 55, the maximum safe speed will be, say, 55. So (this is simplified, by the way), a train approaching a stopped train ahead will be going along at maximum line speed and will then see its speed checked down sequentially. The target speed on entering the next section will drop section by section as the train goes along, and it will be slowed down in steps. If, at any point, it fails to achieve the target speed before it enters the next block, it will exceed the maximum safe speed when it enters that block and the ATP will step in and brake the train until it is doing the correct speed. Now, the ends of blocks are marked by block marker boards, or coloured signals. So a driver will see the target speed displayed on their speedo fall and will know they need to be doing that speed before passing the next block marker board or signal. If they can't see it yet, they should know where it is from route knowledge. The ATO needs to be told where the block marker boards and signals are in order to drive the train. This information is picked up at each station from the PACs. Makey sensey?

(Please note this is an astonishingly simplified explanation with numbers chosen that are based on reality but are not necessarily actual reality. The blocks may not be limited to one track circuit section either, and I chose numbers of track circuits that are also based on reality, but I didn't actually bother to look up where they were, so don't expect this to conform to reality, because reality is complicated Also I'm only an enthusiast so, I'm sure there are a few errors, but you get the idea).

Would the number of wheel revolutions required not change depending on how worn the wheel is though?  

So, the reason the train stops more often in the rain isn't because of wheel revolutions, it's because the low adhesion causes the wheels to spin faster, the ATP reads this as an 'overspeed' and possibly passing it's last possible braking opportunity so the fail safe dictates that an emergency brake must be applied

All the LUL passenger fleets currently fitted with WSP continue to have it active in Emergency Braking, having been validated/verified to meet relevant standards.
Both types of WSP fitted in the early days of 1973TS (the Picc line fleet) were set up after testing so as not to be active in emergency braking. For this and reasons of general limited effectiveness the equipment was withdrawn from use after a short time.

Had a pig of a train on my first half, it started raining as I left Leytonstone, the train stopped about two cars short at Snaresbrook, just about crept in at South Woodford and then stopped less than halfway into Woodford. That's when I give up and switched Coded (and I didn't call Wood Lane).

Must admit all these manual driving shenanagans amuse me. On the Northern it's quite simple - if one fancies driving manually then one does, any time and any place. As long as the train is not losing time and nothing goes wrong then everyone is happy.

One or two of the controllers do very occasionally try it on though, for example once was 3 late leaving Barnet platform 1, having sat in the platform for ages waiting to get the road whilst a train was signalled into platform 2. There had been more than enough time to leave without either train conflicting with each other, but evidently Seltrac thought otherwise. By Totteridge the signaller called up requesting the train go into ATO as "you're losing time driver". The train stayed in PM and was 2 minutes early by Kennington.

You would've thought that the central line had got through the teething problems by now, but when their lords and masters at the ES stick their noses in then they feel the compulsion to do something, when the fact is the ES created a sensational story out of thin air 🙄

As far as I'm aware, not seen any notices to the contrary, they are supposed to, it was just a convenience for them to take that stance to show the ES that they disciplined the driver from the door open incident, but to clarify, nothing has happened to that driver, he is still driving trains and 'thinks' they might do something, but as yet all he has had is an 'advisory' to contact the controller in future to let them know