Model Railroad Signals


Union Kingdom Railway Signaling System for modelrailroad


Youtube movie of Model Railroad Signaling System Part 9-2

Youtube movie of Model Railroad Signaling System Part 9-1

Note : Some following pictures were taken from RailPictures.Net

I love UK railway and have been in UK but not familiar to UK signal rule in the real railway. This signaling system is based on my researches of some articles and web sites (thanks to RailPicturesNet for taking some next photos from there) but I don't exactly know if my understanding is strictly correct. If you have any comment and advice, please mail me. My mail address is shown on the top area of the top page of this web site. Thanks.



Signal types observed in Union Kingdom Railway

The next figure shows the typical color signal aspects in UK railway. There are some variations of signals like this. Single and Two-apertures signals are modern types and equiped with multi-color LED lights which can show more than two colors. From the left, Red(R), Yellow(Y), Double-Yellow(YY) and Green(G). Single and Three-apertures signals work under the three-aspects signal rule. Two and Four-apertures signals can work under the four-aspects signal rule.

Fig.1 :  In June 2013, this figure was modified by Paul Harman ( see his DCC stationary signal decoder SC1 at  http://www.coastaldcc.co.uk/products/productinfo.php?id=1859 ),

where two-apertures signal shown above is classified into 2- or 4-aspects types which are different for the distance between the LED lights.

The 2-aspects signal will be operated in a combination with a distant signal.

Thanks to P.Harman.

 

 

 

The next picture shows the single-aperture signals showing R (Stop). The base board is similar to that of two-apertures signal.

Photo 1:  UK's railway signal is based on the route signaling. On the next picture, the left signal has a feather route indicator which consists of straight-lined five white lights. This indicates which diverging route is set just beyond this point. The right signal has not a feather route indicator but, instead, has a theather route indicator which is a square box beside the signal.

Photo 2: Theather route indicator can show numbers or alphabets which can specify each diverging route. The small triangle box beside the signals is the shunting signal which is usually dark (non-lit) excepting shunting operations.

Photo3:

Photo 4:

The feather route indicator is applicable for six diverging routes at max. The upward and downward feathers are not assigned. The rightward and leftward feathers respectively can have three-angles by 45 degrees. The next picture shows a case of three diverging routes in addition to a straight route.

Photo 5:

In the next picture, the shunting signal observed on the right looks standalone and is showing Red(Stop) at this time. If the shunting signal is located just beside a main signal, it will be dark excepting the shunting operations.

Photo 6:


The next shows the basic signal-aspects sequence. The upper two patterns are usual and modern cases. A piece of signal is located in each block. The lowest pattern is an old style signaling system used since the age of the semaphore signals. In this pattern, normal and distant signals are combined in each block, like this figure. The square signals are called the distant signal which is directly operated (syncronized) together with the next normal signal. Note that the shape of distant signal may not be, in fact, square.

Figure 2 : Basic signal sequences


Approach Release from XXX operations:

As one of unique signal operations in UK, "Approach Release from XXX" is known, where XXX may be either R or Y. When a train approaches a diverging point with any speed limit slower than the track speed, entry signal Sg4 shows R or Y, until the train passes Sg3 and then approaches Sg4. Hence, the train's driver will reduce the train speed. When the train approaches Sg4, Sg4 is upgraded to G (Clear) at point P1. Hence, the train's driver will pass the diverging point at the safe speed. The next figure shows the example of "Approach Release from Red".

Figure 3:  Approach Release from Red

The next figure shows an example of "Approach Release from Yellow". This may be used in less-restrictive diverging route than "Approach Release from Red". This must be applied in four-aspects signaling section which can show YY at Sg3.

Approach Release from Yellow.

The next figure shows an example of "Approach Release from Yellow" with flashing-Y at Sg3 and -YY at Sg2.

When Class 253 & 254 called as High Speed Trains or InterCity 125s was introduced, this signal sequence including these flashing-aspects was introduced. When there are more than two diverging routes, these flashing-aspects only refer to the highest speed diverging routes.

Figure 4:  Approach Release from Yellow with Flashing-aspects


splitting distant signal operations:

At present, I don't exactly know about this operation. The following explanations may be partially incorrect. If you know about that, please mail me, thanks.

The next shows an example of splitting distant signals. In this case, note that "Approach Release from XXX" shown above is not applied. Instead, Sg2 and Sg3 have additional signal heads called as splitting distant signals shown as square boxes in this figure.

In general, "Approach Release from XXX" does NOT let the train driver know which diverging route is set. Rather, he can only know the diverging limit speed set there. However, originally, signals Sg3 (and Sg2) in the route signaling system may have to indicate which diverging route is set, rather than the diverging limit speed. To do so, signals Sg3 (and Sg2) may have splitting distant signals just beside the signals.

When Sg4 works for the straight route, the splitting distant signals at Sg2 and Sg3 show respectively YY and Y, as shown in the upper pattern. Because, Sg4 is assumed to be Red for the diverging route.

While, when Sg4 works for the diverging route, the splitting distant signals at Sg2 and Sg3 show G, as shown in the lower pattern. In addition, main signals at Sg2 and Sg3 respectively show YY and Y because Sg4 is asummed to be Red for the straight route.

If Sg4 shows either R or Y, the splitting distant signals at Sg2 and Sg3 may change from these patterns shown in this figure.

Figure 5:  Outer and Inner splitting distant signals

(Sg2 is Outer and Sg3 is Inner)

Table 1:   UK signal rule implimented in this signaling system


Download PIC16F648A Hex-code for Union Kingdom Railway

 

Circuit Diagram of type-A board:  This board can operate two-signal masts (i.e. bi-directional)  in  no-diverging (straight) route.

R=220ohm,  PC=TLP521(e.g. Toshiba),  SW1-1,1-2,2-1 and 2-2 set the signal type of RA6 and RA7 explained below.

For the details of this board, see the Japanese version or North-american version.

 

How to assemble this signaling system is the same as that of Japanese version and North-American versions such as UP, BNSF, CROR and CSXT, which are shown on the other pages. To assemble this signaling system, you must register the next HEX-codes in Microchip's PIC16F648A on type-A and -B signal boards, by using PIC writer, such as PICkit3 released from Microchip.

The next HEX-codes are the latest UK version. In contrast to the other countries versions, the slow change mode in which signal aspects slowly change is not yet installed.

Downdload of hex-code for Type-A board:

uk-signal-a13.HEX for type-A board

This program linked above is operatable under one of the following four signal types. Jumper plugs for (RA6,RA7) on type-A signal board must be set, corresponding to the signal type you want.

 
(RA6,RA7) must be switched to select one from the next types. 
(1,0)    ; 3-aspect signal type for 1-aperture 3-colors signal
(0,1)    ; 3-aspect signal type for standard 3-colors signal
(0,0)    ; 4-aspect signal type for standard 4-colors signal
(1,1)    ; 4-aspect signal type for 2-apertures multi-colors signal
 
 

Type-BL board (Leftward diverging version)  This board can operate to select one of diverging routes in the serial communication of signal operations.

For the details of this board, see the Japanese version or North-american version.

 

 

Type-BR board (Rightward diverging version) This board can operate to select one of diverging routes in the serial communication of signal operations.

For the details of this board, see the Japanese version or North-american version.

 

 

Downdload of hex-codes for Type-B board:

A Type-B board which is a route selector unit can connect three diverging routes and can select one of them by operating DCC stationary decoder. The DCC stationary decoder is also homemade (see below) and mounted on the signal board.

Routes-B and C are assigned to one of "Aprch Release from XXX". While, Route-A is assigned to straight (non-diverging) route.

For more than three routes at a diverging point, some type-B boards can be connected in a series, which is called as the cascade connection. When the cascade connection is formed, the selection of "Aprch Release from XXX" works only for the first nesting type-B board. On the other type-B boards, the selection of "Approach Release from XXX" is disable (ignored) and follows the setup of the first nesting type-B board.

Downdload of asm-program for Type-B (pattern-1):

"uk-signal-b13-auto1.HEX" for Type-B board

 
;;;;;; Route-A connected to (RB6,RB7) is activated, when (RA6,RA7) is (0,0)
    ; This must be non-diverging (straight) route. 
 
;;;;;; Route-B connected to (RB4,RB5) is activated, when (RA6,RA7) is (0,1)
    ; Diverging route for Approach Release from Red 
 
;;;;;; Route-C connected to (RA4,RA5) is activated, when (RA6,RA7) is (1,1)
    ; Diverging route Approach Release from Yellow (Y)
 
;;;;;; Non-Red route is automatically selected from route-A,B,C, when (RA6,RA7) is (1,0)
 

Downdload of asm-program for Type-B (pattern-2):

"uk-signal-b13-auto2.HEX" for Type-B board

 
;;;;;; Route-A connected to (RB6,RB7) is activated, when (RA6,RA7) is (0,0)
    ; This must be non-diverging (straight) route. 
 
;;;;;; Route-B connected to (RB4,RB5) is activated, when (RA6,RA7) is (0,1)
    ; Diverging route for Approach Release from Red 
 
;;;;;; Route-C connected to (RA4,RA5) is activated, when (RA6,RA7) is (1,1)
    ; Diverging route Approach Release from Yellow (Yf)
    followed by Flashing-Y and Flashing-YY 
;;;;;; Non-Red route is automatically selected from route-A,B,C, when (RA6,RA7) is (1,0) 
              

The difference between these HEX-codes is only for Route-C. Both rules of "Aprch Release from Yellow" and "Aprch Release from Yellow followed by Flashing-Y and Flashing-YY" cannot be simultaneously applied to a diverging point.

At present, 3-aspect signal type for standard 3-colors signal and 4-aspect signal type for standard 4-colors signal are only available, in contrast to type-A boards. Hence, 1- and 2-apertures signals are not available.


HEX code for DCC stationary decoder

This code is registered on PIC16F648A for homemade DCC stationary decoder mounted on type-A and -B boards. For how to assemble the homemade DCC decoder and its circuit diagram, refer the pages for Japanese and North-american versions.


Photo 1a

Photo 2a

The signal boards Type-A and Type-B are the same as those of the other conutries' versions. The signal wirings are shown below.

Fig1a: Wirings of 3-apertures and 4-apertures signals.

Fig2a:  Wiring for single and two-apertures signals. For single-aperture signal, remove the upper aperture in this wiring. At present, single and two-apertures signals are not yet available on type-B board. Available only for Type-A board.

For type-B, feather signal (indicator) can be attached like this.

Fig3a:

Photo3a:  On the trainsition stage from Red (the left) to non-Red (the right), which is during a short time (1sec), Feather is indicated above Red (the middle).


Photo4a: Approach Release from Yellow. Before releasing.

Photo5a: Approach Release from Yellow. Before releasing.

Photo6a:  Approach Release from Yellow. After releasing

Photo7a: Approach Release from Yellow. The signal is released to YY because the next signal is Yellow (invisible in this photo).


Photo8a : Approach Release from Red. Before a train approaches the entry signal. The 1st intermediate signal is showing Yellow (Caution)

Photo9a: After releasing.

Photo10a:



Splitting Distant Signal Operations;

Instead of "Apprch Release from XXX" mentioned above, the Splitting Distant Signals may be located and operated. This setup is simply possible. To execute the operations, for each diverging route, connect some type-A boards in a series, without Type-B board, as follows.

Assume that trains proceed leftward and there are three-diverging routes-A,B,C. (1st) entry signal Sg1 is mounted on type-B board. This Type-B board must be programed by the next HEX code because of non-use of "Apprch Release from XXX".

Downdload of asm-program for Type-B (pattern-0):

"uk-signal-b13-auto0.HEX" for Type-B board

This HEX code is the same as "uk-signal-b13-auto1.hex", excepting "Apprch Release from XXX" is disable for Routes-B and -C.

As train proceeds, the train driver encounters Sg4, Sg3, Sg2 and then Sg1 in the order.

In above figure, the most-left three type-A boards for (route-A), (route-B) and (route-C) are normally connected to type-B board by solid lines which is 10pin flat cables. Then, the type-B board is normally connected to the preceding type-A boards along the main track. This setup is normal. But, note that type-A boards for Sg2" and Sg3" have no signal to be operated. Note that Sg2" and Sg3" are signals for opposing (i.e. rightward) travels. Then, Sg4 is normally mounted on the preceding type-A board along the track, as shown on this figure.

For splitting distant signal operations, some additional type-A boards for Sg2, Sg3, DSg1, DSg2, DSg3 and DSg4 must be employed "without occupancy detection units". Inner distant signals DSg1 and DSg3 for (route-B) and (route-C) must be respectively attached beside (below) the 2nd home signals Sg2 and Sg3. Outer distant signals DSg2 and DSg4 are also beside Sg2 and Sg3.

Points c1, c2 and c3 just mean the parallel connection of the 10pin flat cables. E.g., the most-left type-A board (route-B) may affect type-B board when Route-B is selected on the type-B board. Simultaneously, the type-A (route-B) board directly also always affects type-A board for DSg1 and then DSg2.



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