British signalling for Zusi 3

[Christian Gründler]

Fortunately the principles of railway signalling do not differ much between Germany and the United Kingdom (guess why ). The signal logic of Zusi 2 allows to create British signals which work at least approximately as in reality. But there are some details which need special progamming if they shall be represented correctly. I shall deal with these later; first some remarks about the British

multi-aspect signals:

Multi aspect signals may display red, yellow and green (3-aspect signal) or red, yellow, double yellow and green (4-aspect signal). The former are combined signals like the German Ks signals, the latter are multi section signals like the German Hl signals. But there is one big difference: british running signals never indicate the permitted speed!

Nevertheless 4-aspect signals can be realized with Zusi 2 by using fictitious speeds (about 500 km/h) for the different aspects. This works perfectly during the simulation, but has the slight drawback that the graphics of the assessment at the end of the journey looks funny (not wrong, but with a maximum speed of 500 km/h).

By now I know that it is possible to control the working of these signals by using the ID instead of speed. Alas, we will need the ID also for

approach control at junctions:

As there is no British signal aspect similar to the German Hp2, the driver must be warned in an other way that facing points are set for the diverging route. One possibility is to hold the junction signal at danger until the train is near and has slowed down sufficiently. This can be done in Zusi by using the event "1000 m vorher keine Fahrstraße" and works fine.

Another possibility are "flashing aspects": when approaching the junction, the driver sees the sequence green, yellow flashing, yellow (3-aspect signals) or green, double yellow flashing, yellow flashing, yellow (4-aspect signals).

Please note that with flashing aspects 3-aspect signals can display 4 different aspects and 4-aspect signals can display 6 different aspects, which must be represented by the signal matrix! This can be done by using fictitious speeds (has been done for Zusi 2 and works), by a combination of speed and ID or by ID alone:

Code: Alles auswählen

Matrix of a 3-aspect signal:
                         0              -1              -1              -1
1st line: Stop         r,v=0           r,v=0           r,v=0           r,v=0
2nd line: Proceed      y,v=-1,ID=2     g,v=-1         yf,v=-1,ID=3     g,v=-1

Matrix of a 4-aspect signal:
                         0               -1             -1               -1              -1
1st line: Stop         r,v=0            r,v=0           r,v=0           r,v=0           r,v=0
2nd line: Proceed      y,v=-1,ID=2      g,v=-1         yf,v=-1,ID=3    yy,v=-1        yyf,v=-1

signal aspects: r   = red
                y   = yellow
                yy  = double yellow
                yf  = yellow flashing
                yyf = double yellow flashing
                g   = green

You may be surprised by "ID=2" and the last column in the matrix of the 3-aspect signal. The reason is, that 2-, 3- and 4-aspect signals may be mixed in arbitrary sequence. Whereas 2-aspect signals will (hopefully) ignore the IDs, 3-aspect and 4-aspect signals must work correctly in any arrangement.

The matrix of the junction signal has a third line for the diverging route. In this line "ID=2" must be changed to "ID=1". Moreover the first signal at the diverging route beyond the junction must not be cleared before the train has passed the AWS magnet in front of the junction. This can be realized by the event "1000 m vorher keine Fahrstraße"; if 4-aspect signals follow at shorter distance, an event "500 m vorher keine Fahrstraße" may be needed.

Questions @Carsten: Do you think that my idea will work? What does Zusi 3 do if an ID is reported by the following signal for which there is no column in the signal matrix? Is the result unforseeable or well defined? If an ID which cannot be "satisfied" is always interpreted as zero, we do not need the last column in the matrix of the 3-aspect signal.

Regards
Christian

(To be continued.)

[Christian Gründler]

Now for something more complicated which cannot be realized with Zusi 2 and needs special programming in Zusi 3:

Rule 39(a) alias (TS1)4.6.1

In the words of the current rule book, this rule says: "If you cannot clear a stop signal, you must not clear any associated signals on the approach to it until the train has stopped or nearly stopped at each signal in turn."

This rule applies only to semaphore signals.

Let me explain it by the example of a signalbox which controls (in each direction of a double line) the following signals:

• distant signal ("Einfahr-Vorsignal")
• home signal ("Einfahrsignal")
• advanced starting signal ("Zwischensignal")
• starting signal ("Ausfahrsignal")

Suppose the line is clear up to the starting signal, but not beyond. In this case all other signals may not be cleared at once, but only one after the other when the train is near to the respective signal. (The distant signal is never cleared, as the home signal is at danger when the train passes the distant signal!) The obvious reason for this rule: there are no distant signals for the advanced starting signal and the starting signal. By clearing the signals late, the train is forced to move slowly. (Same principle as the first type of approach control mentioned above.)

(to be continued)

[Carsten Hölscher]

Zusi3-signalling is based on "Fahrstraßen" (english expression?). So you can't transfer the Zusi 2-concept directly.

Carsten

[Stefan_K]

Zusi3-signalling is based on "Fahrstraßen" (english expression?). So you can't transfer the Zusi 2-concept directly.

Carsten

I think "Fahrstraße" translates into "route" or, a bit more specific, "pre-set route".

[StefanSchmidt]

Fahrstraße :
Schaut mal hier:
http://dict.leo.org/ende?lp=ende&lang=d ... &relink=on" target="_blank
StS

[Rui Fonseca]

"pre-set route".

If that is what I think it is, it is how trains are controlled here in Portugal by CTC. The train actually tells the CTC computers the way it wanst to go when entering a control region and the CTC computer just plots it's itinerary if no incompatibilities are found. Of course the operators can override this for a number of reasons.