Upcoming Games


Full list
Add a game

Point normalisation alarm

You are here: Home > Forum > Simulations > Released > Brighton > Point normalisation alarm

Page 1 of 2

Point normalisation alarm 10/07/2013 at 21:35 #46968
Oddjob
Avatar
116 posts
What is a point normalisation alarm and how do you deal with or stop them?
Last edited: 10/07/2013 at 21:36 by Oddjob
Log in to reply
Point normalisation alarm 10/07/2013 at 21:38 #46969
Peter Bennet
Avatar
4772 posts
It's covered here

Peter

I identify as half man half biscuit - crumbs!
Log in to reply
The following users said thank you: Oddjob, Farcical
Point normalisation alarm 10/07/2013 at 21:41 #46972
Oddjob
Avatar
116 posts
Most grateful thanks
Log in to reply
Point normalisation alarm 10/07/2013 at 21:44 #46973
Steamer
Avatar
3264 posts
Out of interst, if the designer has included a circuit to tell the signaller to restore the points, why not make the points self-normalising? Surely it can't require much more wiring?
"Don't stress/ relax/ let life roll off your backs./ Except for death and paying taxes/ everything in life.../ is only for now." (Avenue Q)
Log in to reply
Point normalisation alarm 11/07/2013 at 07:57 #46975
clive
Avatar
2112 posts
Online
The alarm can be non-safety-critical logic (note that nothing on a signalling panel is safety-critical; it's all checked in the interlocking). Self-normalizing the points is safety-critical and so requires a higher standard.

Also there may be situations where it is reasonable to leave the points reversed. The first time I saw one of these in anger, it was at a depot entrance (Three Rivers, I think, on Derby panel anyway) and the main line was blocked beyond them, so there was no point (sorry) in having the points motor back and forward for every train.

Log in to reply
Point normalisation alarm 11/07/2013 at 08:59 #46976
Hooverman
Avatar
301 posts
Well at least it makes this sim realistic to the real thing. We have no self normalising points at Brighton. In fact there are only four sets of self normalising points in the whole of the main horse shoe panel (panels 1a to 6), these being located at South Croydon, Caterham, Tattenham Corner and Gatwick Airport. On panel 7 (Horsham Panel) all of the points that join the Up and Down Main/Horsham lines from either the platform loops or sidings will self normallise.
Log in to reply
Point normalisation alarm 11/07/2013 at 11:55 #46988
Steamer
Avatar
3264 posts
" said:
The alarm can be non-safety-critical logic (note that nothing on a signalling panel is safety-critical; it's all checked in the interlocking). Self-normalizing the points is safety-critical and so requires a higher standard.
What's the difference between an electrical signal sent from the points switch operated by the signaller and an electrical signal sent from the alarm system? Also, what's the difference between safety critical and none-safety critical logic?

Just to be clear, I'm trying to get my head around how the system works in real life, I'm not complaining about the simulation.

"Don't stress/ relax/ let life roll off your backs./ Except for death and paying taxes/ everything in life.../ is only for now." (Avenue Q)
Log in to reply
Point normalisation alarm 11/07/2013 at 12:32 #46993
Stephen Fulcher
Avatar
1560 posts
In terms of Western Region E10k interlocking, there are essentially two levels - safety and non-safety.

The safety functions are all either BR930 series signalling relays or equivalent and are built to a very high engineering standard to ensure that only EITHER front or back contacts can be made at any one time respective to whether or not the coil is energised. The safety functions are basically anything that does the actual interlocking (points, signals, route locking, approach locking, timers etc.). Anything that actually moves points, alters the aspect of a signal or level crossing will be a safety relay.

The non-safety functions are generally Post Office 3000 style relays which are much cheaper to buy. They are however nowhere near as reliable and the older type ones even have exposed contacts. They are only used for functions that are not safety-critical such as indications to the panel and controls from the panel, plus some other non-vital issues such as earth leakage, filament failure and intruder alarms.

If a non-safety relay fails wrong-side (for instance the front contact of a UR remaining made with the route not set on the panel) then the absolute worst that could happen would be the interlocking calling a route the signalman did not want. There is no safety issue with this as the route will only prove and the signal clear if the safety circuits allow it. Ironically, self normalisation of points in E10k is triggered by a non-safety circuit, although the points will only call normal once the safety side of the system deems it safe.

Vital and non-vital logic is essentially the same as I have detailed above. I am not an expert in data preparation for IECC and SSI but my assumption would be that the non-vital probably requires only one computer to decide it is right, but the vital is either duplicated or triplicated. There will be people with more knowledge of this issue than me.

There is a general move against self-normalisation on certain safety grounds anyway, as it is considered safer for the signalman to manually call the points normal as opposed to automatically doing so at the interlocking level.

Log in to reply
The following user said thank you: Steamer
Point normalisation alarm 11/07/2013 at 16:17 #47005
Late Turn
Avatar
660 posts
" said:
If a non-safety relay fails wrong-side (for instance the front contact of a UR remaining made with the route not set on the panel) then the absolute worst that could happen would be the interlocking calling a route the signalman did not want. There is no safety issue with this as the route will only prove and the signal clear if the safety circuits allow it.

I'd beg to differ on that point - it could present a significant safety issue if the signal was being maintained at danger to, for example, protect a line blockage (or possession), or because the driver needed to be given instructions (examining the line, AHB on local control, cows on the line and so on) when the interlocking called a route of its own accord.

Log in to reply
Point normalisation alarm 12/07/2013 at 14:29 #47047
Stephen Fulcher
Avatar
1560 posts
That is true and I agree with you.

It is more from a signalling perspective that I was referring - namely that no route that was not available could set itself, nor would a signal clear that was not safe to do so as far as the interlocking was concerned.

Log in to reply
Point normalisation alarm 12/07/2013 at 21:34 #47060
Firefly
Avatar
521 posts
Probably not a lot more that I can add here.

As Stephen says in E10k a different standard of relays are used for the vital/non-vital circuitry. A BR930 series relay cost a minimum of £200, a post office relay could probably be picked up for £2 or less.

It's not only about the relays, panel functions are very often transmitted to the relay room via a panel multiplex. This enables all of the functions to be sent down a single pair of wires. A panel multiplex is not guaranteed to fail safe.
Sometimes rather then using relays to control the route setting we use ERSE (Electronic route setting equipment). Once again ERSE is not fail safe.
FInally when using relay interlockings we have remote interlockings which are some distance from the panel. Take Brighton as an example. The push buttons and switches operate non-vital relays in three bridges relay room. The non vital relay state is then transmitted along a TDM system (Time Divisional Multiplex) to Brighton which is also non-vital. The TDM receiver in Brighton relay room controls non-vital relays which repeat the state of the relays in Three Bridges relay room. These non-vital TDM repeat relays then give commands to the Vital geographical relay interlocking. Only the interlocking has the safety integrity to be considered failsafe. SIL3 or 4.

In relay interlockings self normalising points took a lot more relays and a lot more testing so they were used sparingly. A point normalisation alarm is fairly cheap and as Clive said is done in the non-vital circuitry at the panel end. These days with electronic interlockings they're used more extensively, however there's still a greater cost for design and testing.

FF

Log in to reply
The following user said thank you: Steamer
Point normalisation alarm 19/08/2013 at 10:23 #48586
Charlytos
Avatar
267 posts
Read replies from this theme. Question is, points P1830B and P1830A, which is its location? Aren't shown on screen with that name.
I looked that entrances L11 and L21 have flashing the short track. Is that red normalization alarm problem?. Found window with key F11 over different problems, points, tracks,...
Open points selected P1830A, appears small screen then put, where is selected auto as normal, then white line flashing is out, but junction point is flashing and appear more points normalization alarm: 1839 and 1851, making same action. Is correct how I made it?.
After than trains have passed by other route points appear new normalization alarm messages for those points. Please clarify how to make correct normalisation points. Thanks.

Last edited: 19/08/2013 at 10:56 by Charlytos
Log in to reply
Point normalisation alarm 19/08/2013 at 11:43 #48588
DriverCurran
Avatar
547 posts
Carlos

You need to left click either end of the crossover that is flashing, but when you do this make sure you are clicking on the point itself, once you have clicked the point they will show blue (this indicates that you have pegged the points normal) at this stage the flashing track circuit will go out and cancel the normalisation alarm. However you now have to left click the points again in order to un-peg them back into operating when a route is set (at this stage the track around and including the point should be grey in colour)

Paul

You have to get a red before you can get any other colour
Log in to reply
The following user said thank you: delticfan
Point normalisation alarm 19/08/2013 at 12:06 #48589
Charlytos
Avatar
267 posts
Thanks Paul to clarify how to make it! I shall prove it now that detail!...
Log in to reply
Point normalisation alarm 20/08/2013 at 00:49 #48619
DriverCurran
Avatar
547 posts
Did you manage to get that issue sorted out Carlos?

Paul

You have to get a red before you can get any other colour
Log in to reply
Point normalisation alarm 14/11/2013 at 21:02 #51553
DaveBarraza
Avatar
76 posts
General sim-engine question:

How much of the vital logic is simulated by SimSig?

I've built panel simulations for a US property, and it was agreed that the only way to make the simulated panel work exactly like the real one was to take all of the vital logic and write it into the simulation software.

For a relay plant, that was a non-trivial task!

Log in to reply
Point normalisation alarm 16/01/2015 at 15:46 #67933
delticfan
Avatar
476 posts
I'm just having my first run with Brighton, and have just proved that it's good to check for answers to queries before raising a question. I've just had a couple of 'Point Normalisation Alarms' and have never come across this on any other Sim. Thanks to those who raised this and who also answered the query.
Another interesting Sim, and reasonably controllable by single player.


Mal.

Log in to reply
Point normalisation alarm 16/01/2015 at 16:35 #67937
Jersey_Mike
Avatar
250 posts
" said:
General sim-engine question:

How much of the vital logic is simulated by SimSig?

I've built panel simulations for a US property, and it was agreed that the only way to make the simulated panel work exactly like the real one was to take all of the vital logic and write it into the simulation software.

For a relay plant, that was a non-trivial task!
I don't know why they would require that. Panel signaling simulators are all well and good, but at the end of the day there is no substitute for on the job training. Past a certain point the tower operator simply isn't going to remember all the corner cases unless they encounter them in a real life situation. Then you have the quirks caused by physical hardware errata. The simulator should focus the trainee on the basics of moving trains through their territory, leave the rest to experience.

So take the real life example of a race condition on a number of Amtrak interlocking panel interfaces where the switch blocking device immediately cuts the 120v power to the point machine, even if the points are still on center. An inattentive or rushed operator can leave a switch in a derailing position while physical steps (throw and block) needed before they give permission past a stop signal. By rule they should observe the point indication, but point failures are rare and giving permission past a stop is uncommon. So yes that is something that could be simulated, but on the other hand the situation could just be explained a good reason to follow the rules and double check all switch positions before giving permission past a stop signal.

In your case would it really be necessary to simulate the Key-by logic? The tower operator isn't even involved with that process.

Log in to reply
Point normalisation alarm 16/01/2015 at 17:48 #67943
GeoffM
Avatar
5089 posts
" said:
General sim-engine question:

How much of the vital logic is simulated by SimSig?

I've built panel simulations for a US property, and it was agreed that the only way to make the simulated panel work exactly like the real one was to take all of the vital logic and write it into the simulation software.

For a relay plant, that was a non-trivial task!
(Sorry I didn't see this before)

SimSig interlocking logic is based on SSI (and by extension Westlock and Smartlock). The majority of the functionality is encapsulated but there are bits which aren't worth doing - red-retaining logic for comms failures, for example. There was an issue with preset shunts for years which didn't affect the functionality at all except in a particular corner case, and nobody spotted it (or mentioned it) until a couple of years ago. I was aware of it but didn't "fix" it until it was raised. Nobody else noticed.

Several years ago, for my former employer, I wrote software which simulated Westpac geographic units (presealed cases of relays performing a certain function, such as a signal or point, connected together with multi-core cable). That proved interesting because of the way current could flow in either direction - in some cases energising the same relay with the positive and negative terminals reversed. I proved it could be done but we didn't take it any further.

In the above case it was far easier to copy the vital logic directly from the circuit diagrams than to try to redraw it without bits that would not be essential for simulation purposes. If you were drawing your own relay diagrams from first principles then yes I'd say to drop the non-essential bits.

SimSig Boss
Log in to reply
The following user said thank you: DaveBarraza
Point normalisation alarm 16/01/2015 at 20:56 #67949
Muzer
Avatar
715 posts
" said:
I'm just having my first run with Brighton, and have just proved that it's good to check for answers to queries before raising a question. I've just had a couple of 'Point Normalisation Alarms' and have never come across this on any other Sim. Thanks to those who raised this and who also answered the query.
Another interesting Sim, and reasonably controllable by single player.


Mal.
This is explained in the manual. Many of the points that lead onto lines onto depots should be set "normal" manually after each use. They flash red when the alarm goes off, the alarm is just a reminder to normalise the points (there is no penalty for seeing the alarm). I don't know why they don't normalise automatically, maybe it would be too hard in the interlocking?

Log in to reply
The following user said thank you: delticfan
Point normalisation alarm 19/01/2015 at 04:06 #68066
DaveBarraza
Avatar
76 posts
Appreciate the response! I guess I'm not familiar enough with the UK platforms to know how "pre-packaged" they are, and by extension how much the sim developers need to deal with the development of interlocking logic to support the sims. I'm used to a world that you guys would call "free-wired" (Free Range?!?)

Quote:
In the above case it was far easier to copy the vital logic directly from the circuit diagrams than to try to redraw it without bits that would not be essential for simulation purposes.


Completely agree. No one gets into arguments about relevancy!
There's a trap in the all-encompassing approach: You just can't set interns loose translating the more complicated networks. If they don't understand which variables are mutually exclusive then they write code for a path over the points normal and reverse at the same time!!!

Quote:
That proved interesting because of the way current could flow in either direction - in some cases energising the same relay with the positive and negative terminals reversed.
That does sound intriguing... Many of the sensible economizing tricks in relay designs don't translate well (or at all) into processor logic (for good reason!!! )

I had to check someones valiant attempt at putting a bidirectionally fed signal control network into ladder logic. They had done a tremendous amount of work on something that was ultimately fruitless: logic can't solve backwards... And they wound up with a vastly increased amount of logic for the processor to solve.

Log in to reply
Point normalisation alarm 19/01/2015 at 04:27 #68067
DaveBarraza
Avatar
76 posts
" said:
I don't know why they would require that.

You're preaching to the converted. From what I understand the labor costs involved with posting tower operators were deemed excessive. They are only entertaining a *reduction* in posting time. It's better anyway to have them send an instructor and an operator over the day the plant is placed in service, and while everyone waits all night for the test train to show up I just go over the moves, and other new stuff with them on the actual panel.


Quote:
In your case would it really be necessary to simulate the Key-by logic? The tower operator isn't even involved with that process.

A key-by triggers the over-run alarm, which the tower operator must acknowledge. The acknowledge button is piped into the event recorder. If permission for the key-by was not granted, and the tower operator does not bang in the train operator, the tower operator gets in trouble. It's a sad state of affairs overall, but now the tower operator is involved in a simple key-by.

Log in to reply
Point normalisation alarm 20/01/2015 at 10:34 #68160
Hooverman
Avatar
301 posts
Buzzer to remind us to normalise the points is broken in real life at the moment, so the amount of times we must forget to normalise the points into and out of Lovers Walk depot and lock it up so they can't move things around must be doing the shunt panel operators head in by now.
Log in to reply
Point normalisation alarm 20/01/2015 at 12:58 #68172
Jersey_Mike
Avatar
250 posts
" said:
A key-by triggers the over-run alarm, which the tower operator must acknowledge. The acknowledge button is piped into the event recorder. If permission for the key-by was not granted, and the tower operator does not bang in the train operator, the tower operator gets in trouble. It's a sad state of affairs overall, but now the tower operator is involved in a simple key-by.
Where, in the RCC or in the towers? That sounds like a non-vital check to me.

If I am not mistaken the NYCTA's entire system of signal overlap protection is designed around allowing trains to use automatic key-by, but the practice is effectively not employed anymore. In Philly the trips deploy as soon as the train clears the block and all key-by is of the manual variety.

BTW if you are wondering "why" things are the way they are, my friend worked in the TA's front office. Management considers the signaling system a form of "manual ATO" that aims to reduce the amount of skill necessary to safely/effectively operate a subway train. They have also proactively slowed the system down to prevent rulebook slowdowns. In Boston the unions have much more clout because if the Green Line is operated to rule the service completely breaks down. In NYC the TA has basically gotten the public used to bad service as the standard taking away the union's only weapon in a no-strike state.

Last edited: 20/01/2015 at 12:59 by Jersey_Mike
Log in to reply
Point normalisation alarm 20/01/2015 at 17:12 #68184
Muzer
Avatar
715 posts
" said:
Buzzer to remind us to normalise the points is broken in real life at the moment, so the amount of times we must forget to normalise the points into and out of Lovers Walk depot and lock it up so they can't move things around must be doing the shunt panel operators head in by now.
Oh, is that the reason? I assumed it was for safety reasons, to do with preventing runaways!

Log in to reply