GENERAL NOTES
SUMMARY OF XSF FLAGS
XSF1 - Allow AØ to close down if detector 3 is occupied/alarmed when FORCE is received.
XSF2 - When set enables detector 3 to call BØ when its presence timer has expired
SUMMARY OF MSS FLAGS
MSS1 - Set on receipt of the “CALL” and remain ON until the “RELEASE” is received.
MSS3 - Set by Abnormal Condition 1 – “Force before TLR”.
MSS4 - Set by Abnormal Condition 2 – “Late Release”.
MSS5 - Set by Abnormal Condition 3 – “Force without Call”.
MSS6 - Set by Abnormal Condition 4 – “Break in Cable Monitor”.
MSS7 - Set by Abnormal Condition 5 – “Booms not Horizontal”.
MSS8 - Set for the duration of the Booms Horizontal input being ON.
MSS9 - Set when the “CALL” is deemed to be established until the “CALL” is removed.
MSS10 - Set when the “FORCE” input is received – used to monitor the “CALL”/”FORCE” interval.
MSS11 - Set when the “PRE-RELEASE” input is first terminated – used to monitor the “PRE-RELEASE”/”RELEASE” interval.
MSS13 - Set when Queue detector 3 places a non-looking call for BØ.
MSS14 - Set when presence time of detector 4 has expired and remain ON for the duration the detector 4 is occupied.
MSS15 - Set when Queue detector 3 is alarmed.
GENERAL OPERATION
The traffic signals operate as “Metering Traffic Signals” to keep the side road railway track clear.
The controller will rest in AØ until BØ is demanded.
·         BØ can be demanded : (a) by Railway input when FORCE is received or 
(b) when presence time for detector 3 expires and XSF2 is set.
SIGNAL GROUP OPERATION
Signal Group 1
SG1 is a 2-aspect (R/Y) circle LED displays.
SG1 is Blank during AØ green.
Signal Group 2
SG2 is a dummy signal group (no displays on site) that operates during BØ.
DETECTOR OPERATION
Detector 3
Detector 3 places a non-looking call for BØ when its presence time expires and XSF2 is set.
When detector 3 is alarmed, MSS15 flag is set to inform TMC for priority for loop repair.
Detector 4
When presence time for detector 4 has expired, set MSS14 for the duration the loop is occupied. 
ALARM STATUS – QUEUE DETECTORS 3 & 4
If detector 3 and/or detector 4 are on continuously for a time greater than the time specified in Special Purpose Time Setting No. 9, cancel its call functions (apart from when it was first activated) until the detector again changes state.
When the controller is on-line to SCATS and a queue detector is continuously ON for the periods as specified by the SCATS TDA message, then a detector Alarm (DA) will be generated.
RAIL LINK NOTES
1 GENERAL INTERFACING REQUIREMENTS
Electrical interfacing between the traffic signal controller and the level crossing controller is provided by a multi‑core telephone‑type cable having at least 10 pairs.  The wiring is detailed in the Standard Rail-Link Cable Termination Chart (Refer page 4/7).
1.1 STANDARD RAIL LINK INPUTS
For a standard installation, the following five inputs are generated by the rail crossing control system and fed into detector inputs in the traffic signal controller:
·           CABLE MONITOR  via Detector 8 (normally ON)
·           PRE‑RELEASE  via Detector 9 (normally ON)
·           RELEASE/FORCE (R/F)  via Detector 10 (normally ON)
·           CALL  via Detector 11 (normally OFF)
·           BOOMS HORIZONTAL  via Detector 12 (normally OFF)
Each of these inputs is generated from a rail level crossing relay. Each can be in the On or Off state.
1.2 STANDARD RAIL LINK OUTPUTS
The traffic signal controller generates the following two outputs, which are sent to the rail crossing control system through a special signal group:
·           TRAFFIC LIGHT RESPONSE (TLR) via SG4
2 BASIC OPERATING PROCEDURE
The TYPICAL SEQUENCE CHART on page 4/6 shows the sequence of events and the change in state of each input and output.
2.1 CALL 
When the "CALL" input is received (i.e. Detector 11 has been activated for the time specified in Presence Timer No. 11), carry out following actions:
-            Start CALL DELAY timer (Special Purpose Timesetting No. 10). When the CALL DELAY timer expires, the CALL is deemed to be established. Operation of BØ (Track Clearance Phase) is described below.
-            Set MSS1 at the point when the CALL is received. MSS1 will remain on until the "RELEASE" is received.
2.2 TRAIN PHASE SEQUENCE
2.2.1 Track Clearance Phase
BØ is the track clearance. It operates after FORCE is received before the booms are lowered in order to clear off the tracks any vehicle which may inadvertently be on them.
When XSF1 flag is set, BØ can only operate if Detector 3 is occupied or Detector 3 is alarmed when FORCE is received.
2.2.2 Train Phase
AØ operates following the track clearance, BØ.
2.3 TRAFFIC LIGHT RESPONSE (TLR) 
The controller provides phase status information to the Rail Authority in the form of the TLR output (SG4). The TLR output is commenced at the end of AØ minimum green and is maintained until the PRE-RELEASE input is reinstated.
2.4 FORCE
The FORCE is indicated by the RELEASE/FORCE input going off.  This occurs when the train enters the control section causing the red lights at the crossing to flash and bells to ring. 
When FORCE input is received:
-            No XSF1 set: Close down AØ without violating its phase minimum green whether detector 3 is occupied / unoccupied.
-            XSF1 set: Close down AØ without violating its phase minimum green provided detector 3 is occupied / alarmed only.
2.5 BOOMS HORIZONTAL
On receipt of this input is an indication that all the booms have reached horizontal. On receipt of the BOOMS HORIZONTAL input, the MSS8 flag is set and remains set until the BOOMS HORIZONTAL input turns off. MSS8 is used to monitor the duration of the booms closure.
Terminate BØ when detector 3 is vacated without violating BØ minimum green after Booms Horizontal input has been received.
Terminate BØ after its minimum green if detector 3 is alarmed after Booms Horizontal input has been received.
Terminate BØ without violating BØ minimum green after the Special Purpose Timesetting No. 13 expires. This time is used if the Booms Horizontal input is not received due to a fault.
2.6 PRE‑RELEASE
2.6.1 Normal operation for one train
The re-activation of the PRE‑RELEASE input (detector 9) is an indication that the train has cleared the control section of track and that the booms are about to lift.
When PRE‑RELEASE input is received, TLR will change to yellow.
The re-activation of the PRE‑RELEASE input will not affect the operation of AØ.
2.6.2 Second call during train phase or during train phase intergreen
Following receipt of the PRE-RELEASE input, if a second CALL is received when the booms have moved off the horizontal, carry out the same operation as when CALL is first received.
2.7 RELEASE
The Release is indicated by the Release/Force input going to the ON state. This indication releases the traffic signal controller to resume normal vehicle operation.
3 SPECIAL PROCEDURES
3.1 ABNORMAL CONDITIONS
These conditions should not occur in normal operation. However, when they do, appropriate steps should be taken to register the event and to take action as follows.
3.1.1 Abnormal condition 1 ‑ Force before TLR
Although 20 seconds at least should elapse between receipt of a CALL input and the FORCE (termination of the R/F input), there may be occasions when the FORCE occurs prior to the controller issuing the TLR output. This will not force a ‘BLACKOUT’ response and will generate ABNORMAL CONDITION message No. 1 via MSS3.
3.1.2 Abnormal condition 2 ‑ Late Release
The RELEASE TIMER (Special Purpose Timesetting No. 12.) commences counting from receipt of the PRE‑RELEASE.  If the R/F is not reinstated before expiry of this timer, then the controller will generate ABNORMAL CONDITION message No. 2 via MSS4.
3.1.3 Abnormal condition 3 ‑ Force without Call
If the R/F input is terminated without a previous CALL input, the controller will generate ABNORMAL CONDITION message No. 3 via MSS5.
If detector 3 is occupied/alarmed when MSS5 flag activates, immediately close down AØ without violating its phase minimum green and transition to BØ
3.1.4. Abnormal condition 4 ‑ Break in Cable Monitor
If there is a break in the CABLE MONITOR input, the controller will generate ABNORMAL CONDITION message No. 4 via MSS6.
3.1.5. Abnormal condition 5 ‑ Booms not Horizontal
If the BOOMS HORIZONTAL input is not received during the train sequence, the controller will generate ABNORMAL CONDITION message No. 5 via MSS7.  This flag is set at the start of the first phase following release from the train phase sequence if this condition occurs.
3.2 CALL TERMINATION TIMER
When a CALL input terminates prior to the FORCE (in the presence of the R/F input), a timer will begin to count down (Special Purpose Timesetting No. 11).  Any further CALL inputs will reset the timer.  Once the FORCE is received (R/F terminated), the timer is ignored.  If the R/F input is not terminated prior to expiry of the timer, then the controller will AUTO‑RELEASE from the train phase sequence and resume normal vehicle operation. The purpose of this facility is to prevent the traffic signal controller from being "locked up" indefinitely by spurious inputs (in the case of automatic track circuits) or by inadvertent or excessively early calls (in the case of manned signal‑boxes).
3.3 OPERATING MODES
When the CALL input is received, the MSS1 flag is set which can be used to force the controller into ISOLATED operation if the intersection is in other mode of operation.
No compensation technique is required at this intersection.
4 MSS FLAGS – SUMMARY OF OPERATIONS
4.1 MSS1
Set on receipt of the “CALL” and remain ON until the “RELEASE” is received. This flag can be used to force the controller into ISOLATED operation.
4.2 MSS3 to MSS7
These are described under Abnormal Conditions (see 3.1.1 to 3.1.5)
4.3 MSS8
MSS8 is set when BOOMS HORIZONTAL input received. MSS8 remains set until the BOOMS HORIZONTAL input is removed.
4.4 MSS9
MSS9 flag is also set from the point when the CALL is deemed to be established until the CALL is removed. This flag is used to monitor the duration of CALL.
4.5 MSS10
MSS10 is set when the FORCE input is received. This flag can be used to monitor “CALL” and “FORCE” interval.
4.6 MSS11
MSS11 is set when the “Pre-Release” input is terminated. This flag can be used to monitor “Pre-Release” and “Release” interval.
5 VARIATION PARAMETER TABLES
1 Abnormal Condition Message No. 1
A:  "DCL %1 RAIL LINK: FORCE BEFORE TLR
VP11 = 5    ‑ test MSS 
VP12 = 0    ‑ current slot
VP13 = 3    ‑ MSS flag
VP14 = 36   ‑ read Action List
VP15 =     ‑ true Action List No.
VP16 = 0    ‑ no action if false
2 Abnormal Condition Message No. 2
B:  "DCL %1 RAIL LINK: LATE RELEASE
VP17 = 5    ‑ test MSS 
VP18 = 0    ‑ current slot 
VP19 = 4    ‑ MSS flag
VP20 = 36  ‑ read Action List
VP21 =     ‑ true Action List No.
VP22 = 0    ‑ no action if false
3 Abnormal Condition Message No. 3
C:  "DCL %1 RAIL LINK: FORCE WITHOUT CALL
VP23 = 5    ‑ test MSS 
VP24 = 0    ‑ current slot
VP25 = 5    ‑ MSS flag
VP26 = 36  ‑ read Action List
VP27 =     ‑ true Action List No.
VP28 = 0    ‑ no action if false
4 Abnormal Condition Message No. 4
D:  "DNC %1 RAIL LINK: BREAK IN CABLE MONITOR
VP29 = 5    ‑ test MSS 
VP30 = 0    ‑ current slot 
VP31 = 6    ‑ MSS flag
VP32 = 36   ‑ read Action List
VP33 =     ‑ true Action List No.
VP34 = 0    ‑ no action if false
5 Abnormal Condition Message No. 5
E:  "DCL %1 RAIL LINK: BOOMS NOT HORITONTAL
VP29 = 5    ‑ test MSS 
VP30 = 0    ‑ current slot 
VP31 = 7    ‑ MSS flag
VP32 = 36   ‑ read Action List
VP33 =     ‑ true Action List No.
VP34 = 0    ‑ no action if false