Signalling Safeworking Procedures · Effective Date: 01 April 2015 . Preface . The Asset Standards Authority (ASA) is an independent unit within Transport for NSW (TfNSW) and is the
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Mandatory Requirements for Signalling Safeworking Procedures
4. Terms and definitions ........................................................................................................................... 9
5. Network rules and procedures ........................................................................................................... 11
6. Principles of signalling safeworking ................................................................................................. 11
7. Authority to work on the operational signalling system ................................................................. 137.1. Signalling permit to work ................................................................................................................................... 13
8. Authority to operate signalling controls ........................................................................................... 14
9. Testing equipment, tools and radio transmitter devices ................................................................. 159.1. Calibration requirements .................................................................................................................................... 159.2. Radio transmitter devices .................................................................................................................................. 16
10. Derailments and collisions ................................................................................................................. 1710.1. Licensed signalling personnel attendance ....................................................................................................... 1710.2. Signal engineer attendance ................................................................................................................................ 18
11. Signalling irregularities and wrong side failures ............................................................................. 1811.1. Examples of signalling irregularities - wrong side failures ............................................................................. 1911.2. Examples of signalling irregularities - not wrong side failures ....................................................................... 1911.3. Effective elements of a safe condition .............................................................................................................. 2011.4. Treatment of signalling irregularities ................................................................................................................ 2011.5. Investigating signalling irregularities ................................................................................................................ 2211.6. Signalling irregularity certification requirements ............................................................................................. 2311.7. Signalling irregularity reporting requirements ................................................................................................. 23
13. Securing signalling apparatus out of use ......................................................................................... 3013.1. Disconnection from interlocking ....................................................................................................................... 3113.2. Requirements for securing signalling apparatus out of use ........................................................................... 3113.3. Infrastructure booking authority ........................................................................................................................ 3213.4. Signalling disconnection requirements ............................................................................................................ 33
14. Temporary bridging of signalling circuits ......................................................................................... 3714.1. Booking protecting signals into use ................................................................................................................. 3814.2. Approval for temporary bridging ....................................................................................................................... 3814.3. Jumper wires for temporary bridging ................................................................................................................ 4014.4. Testing of temporary bridging ........................................................................................................................... 4014.5. Temporary bridging left unattended .................................................................................................................. 4114.6. Reinstatement advice for temporary bridging .................................................................................................. 4114.7. Non-vital signalling circuits................................................................................................................................ 4114.8. Momentary bridging ............................................................................................................................................ 41
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
15.2. Requesting a release .......................................................................................................................................... 4415.3. Precautions before releasing normal indication locks on signal levers ........................................................ 4415.4. Precautions before releasing normal/reverse locks on point or facing point lock levers ............................ 4415.5. Precautions before releasing normal/reverse indication locks on point levers ............................................ 4515.6. Precautions before releasing point lock relays at standard relay interlockings ........................................... 4615.7. Precautions before releasing signal normal indication relays at standard interlockings ............................ 4615.8. Precautions before releasing approach stick relays ........................................................................................ 4715.9. Precautions before releasing signal route normal relays at route control interlockings ............................. 4715.10. Process for releasing route holding in point lock relay circuits at route control interlockings ................... 4715.11. Providing releases for other situations including computer based interlocking .......................................... 48
16. Management of seldom used signalling apparatus ......................................................................... 4916.1. Seldom used point configurations .................................................................................................................... 4916.2. Seldom used track circuits ................................................................................................................................. 51
17. Requirements for re-railing and associated trackwork ................................................................... 5517.1. Licensed signalling personnel attendance ....................................................................................................... 5517.2. Infrastructure booking authority requirements ................................................................................................ 5617.3. Protection of rail traffic ....................................................................................................................................... 5617.4. Traction return arrangements ............................................................................................................................ 5717.5. Requirements for newly installed rails .............................................................................................................. 5717.6. Reinstatement of signalling................................................................................................................................ 5917.7. Control and issue of temporary rail bonds ....................................................................................................... 59
18. Requirements for providing adequate traction return ..................................................................... 6118.1. Exemption to providing alternative traction arrangements ............................................................................. 6118.2. Work affecting negative return at substations or section huts ....................................................................... 6218.3. Work affecting impedance bonds ...................................................................................................................... 6318.4. Temporary rail connections for overhead wiring ............................................................................................. 63
19. Minor signalling additions, alterations and renewals work ............................................................ 6319.1. Risk mitigation requirements for minor additions, alterations or renewals .................................................. 6419.2. Involvement of signal engineer for risk mitigation requirements ................................................................... 6519.3. Work not affecting the design principle ............................................................................................................ 6519.4. Like for like renewal work ................................................................................................................................... 6619.5. Work affecting the design principle ................................................................................................................... 6919.6. Rewiring and wire repair requirements ............................................................................................................. 7019.7. Documents used for the certification of signalling .......................................................................................... 7219.8. Paralleling of contacts in trackside apparatus ................................................................................................. 72
20. Requirements and scheduling of signalling maintenance .............................................................. 7320.1. Maintaining operational signalling equipment ................................................................................................. 7320.2. Safety related examinations ............................................................................................................................... 7420.3. Maintenance scheduling, reporting and recording .......................................................................................... 75
21. Inspection and testing of vital signalling relays ............................................................................... 7621.1. Precautions and requirements for vital signalling relays ................................................................................ 7721.2. Storage and reuse of vital signalling relays...................................................................................................... 7821.3. Maintenance and overhaul of vital signalling relays ........................................................................................ 79
22. Inspection and testing of signals and signs ..................................................................................... 8222.1. Requirements for periodic and responsive signal sighting ............................................................................ 8322.2. Maintenance and inspection of signals ............................................................................................................. 84
23. Gauging of trainstops ......................................................................................................................... 88
24. Inspection and testing of points ........................................................................................................ 88
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
24.1. Principle of point testing .................................................................................................................................... 8924.2. Prerequisite tasks for point testing ................................................................................................................... 9024.3. Requirements for point lock testing mechanically operated points ............................................................... 9024.4. Requirements for point lock testing power operated points ........................................................................... 9124.5. Requirements for point detection testing ......................................................................................................... 9224.6. Provision for lock slide removal and wide cut notch point lock ..................................................................... 9624.7. Provision to extend point detection limits ........................................................................................................ 98
25. Inspection and testing of track circuits ............................................................................................. 9825.1. Objective of track circuit inspection, testing and maintenance ...................................................................... 9925.2. Track circuit records ......................................................................................................................................... 10025.3. Track circuit inspection and tests ................................................................................................................... 10025.4. Track circuit precautions .................................................................................................................................. 10525.5. Safety critical and safety significant track circuit tasks ................................................................................ 109
26. Inspection and testing of level crossing protection ...................................................................... 11126.1. Maintenance and inspection of level crossing protection equipment .......................................................... 11126.2. Treating reports of level crossing failure ........................................................................................................ 113
27. Inspection and testing of signalling interlockings ......................................................................... 11327.1. Authority to test signalling interlockings ........................................................................................................ 11427.2. Testing altered locking on interlocking frames greater than eight levers ................................................... 11427.3. Interlocking test certificates ............................................................................................................................. 11527.4. Periodic testing of mechanical interlockings ................................................................................................. 11527.5. Periodic testing of relay interlockings ............................................................................................................ 11627.6. Periodic testing of computer based interlockings ......................................................................................... 117
28. Inspection and testing of electrical insulation ............................................................................... 11728.1. Detecting earth leakage .................................................................................................................................... 11828.2. Minimum acceptable values ............................................................................................................................. 11928.3. Determination for further testing ..................................................................................................................... 11928.4. Analysis and test records ................................................................................................................................. 12028.5. Inspection and testing of power supply busbars ........................................................................................... 12028.6. Inspection and testing of electrical conductor insulation ............................................................................. 12128.7. Circuits exempt from periodic insulation inspection and testing ................................................................. 125
29. Specific requirements for computer based interlockings ............................................................. 12829.1. Requirements for Solid State Interlocking systems ....................................................................................... 12829.2. Requirements for Microlok II systems ............................................................................................................. 13329.3. Requirements for Westrace systems .............................................................................................................. 138
30. Surveillance inspections ................................................................................................................... 14130.1. Scope of surveillance inspections ................................................................................................................... 14230.2. Scheduling of periodic inspections ................................................................................................................. 14230.3. Surveillance inspection reports and action requirements ............................................................................ 143
31. Housekeeping and protection of signalling assets ........................................................................ 14331.1. Prevention of water ingress to signalling equipment .................................................................................... 14431.2. Prevention of fire around signalling equipment ............................................................................................. 144
32. Control of signalling documentation ............................................................................................... 14432.1. Requirements for signalling documentation control ..................................................................................... 145
33. Control of signalling security locks and keys ................................................................................ 14633.1. Lock types in use .............................................................................................................................................. 14733.2. Major signal boxes and control centres .......................................................................................................... 14933.3. Configuration and key cutting.......................................................................................................................... 149
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
The position of levers/controls, indications, signals, points, relays and other trackside apparatus
which may be applicable to the circumstances shall be noted.
10.2. Signal engineer attendance When signal engineers are required to attend a derailment or collision, they shall perform the
following functions:
• ensure signalling safeworking protection arrangements are appropriate
• gather evidence and investigate the incident where signalling is suspected to be the cause
• provide safe alternate signal engineering arrangements to facilitate train running as
necessary
• facilitate incident recovery and restoration works
• lead testing and certification requirements, including the provision of an inspection and test
plan
• compile a detailed report
• make recommendations to prevent recurrence of this incident
11. Signalling irregularities and wrong side failures All signalling irregularities and wrong side failures shall be immediately attended, protected and
investigated in accordance with signalling safeworking procedures.
Note: Not all signalling irregularities result in immediate failure. Some may remain in
the system as latent defects or errors to the intended design requirement, which may
later emerge, adversely affecting the safe running of trains.
Predictable, common failure modes such as a single lamp failure (example: on a signal or level
crossing) or a trainstop that is falsely in the lowered position due to a mechanical problem are
not deemed signalling irregularities.
A wrong-side failure is where the failure is not protected by the system design or there are
insufficient effective elements of a safe condition for the particular circumstance, which could
directly endanger the safe running of trains or people. Refer to Section 11.3 for effective
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
11.1. Examples of signalling irregularities - wrong side failures Following are examples of signalling irregularities that are wrong side failures:
• point locking: if points are released under conditions when they should be locked
• point detection: if point detection is made when the points are not in their correct position
• facing points: if a signal can be cleared over facing points when the points are not locked or
correctly detected
• signal: if a valid, less restrictive indication is displayed by a signal than is correct for the
conditions allowed
• rail vehicle detection: if a track circuit or axle counter fails to detect the presence of a rail
vehicle
• level crossing protection: if level crossing protection equipment fails to operate for
approaching trains (excluding an insignificant amount of lights out or one failed bell), and
there is no proving of the boom normal position - does not include the level crossing when
in manual operation
• interlocking: if a release can be incorrectly obtained from the locked position
• vital signalling relay: if a vital signalling relay is falsely energised due to internal or external
interference or defect, which subsequently causes a reduction in system safety
• electric lock: if an electric lock is incorrectly free
• dual control: if the restoration of any one control fails to return the signal to the stop
11.2. Examples of signalling irregularities - not wrong side failures Following are examples of signalling irregularities that are not wrong side failures:
• signal indication: if a signal displays no lights or an irregular combination of lights (invalid
indication)
• level crossing protection: if level crossing protection equipment fails to operate for
approaching trains (excluding an insignificant amount of lights out or one bell), and the
system design provides proving of the boom normal position (XNR) causing the protecting
signals to remain or replace at stop - does not include the level crossing when in manual
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
11.6. Signalling irregularity certification requirements Certification of the signalling system shall be made only when the investigation has concluded,
and upon any of the following conditions:
• a genuine cause has been found or determined and the affected apparatus has been
rectified or otherwise addressed
• the alleged report is proven to be unsubstantiated by thorough testing which has verified
the signalling to be working safely and in accordance with the signalling design
The investigating signal engineer shall refer the incident to another signal engineer who holds
the accountability in any of the following cases for instructions:
• a significant incident occurs (mainline or passenger train derailment, collision or near miss)
and the signalling system is suspected to be at fault
• a recurrence of the irregularity cannot be ruled out, which may potentially result in serious
consequences
• the alleged report or confirmed irregularity cannot be satisfactorily explained and the
investigating signal engineer has deemed the apparatus to remain booked out of use
Note: The signal engineers involved should have suitable experience relative to the
complexity of the subject matter.
11.7. Signalling irregularity reporting requirements A comprehensive report shall be compiled by the investigating signal engineer for all incidents
of signalling irregularity. The report shall contain the events and details of the incident, details of
the technical investigation conducted, test results and applicable evidence such as logs, photos,
statements, and so on. The report shall also include rectification measures, either completed or
proposed, including further investigations if appropriate and any recommendations.
12. Signalling failures (fail safe) All signalling functional failures shall be attended and subsequently reported, recorded and
analysed so that the trends can be identified and appropriate measures be taken to reduce
failures to a minimum. A failure management system shall be used for this purpose.
Repairable items with unique serial numbers that have failed, such as vital signalling relays,
track transmitters/receivers, CBI equipment and so on, shall be identified in the failure
management system so that the performance can be tracked once they are returned to service.
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
12.2.8. Failure of electric locks on signal levers When the 'Normal' electric lever lock fails on a signal lever, the lever shall be kept in the normal
position until the failure has been rectified. The associated signal shall be observed to display a
stop indication.
12.2.9. Failure of interlocking relays At standard relay interlockings, relays such as signal reverse relays, point normal/reverse relays
and releasing switch normal/reverse relays shall not be lifted or falsely energised or released.
At route control interlockings, relays such as route reverse lock relays, point normal/reverse lock
relays and releasing switch normal/reverse lock relays shall not be lifted, or falsely energised or
released.
There is an exception in the case of route holding in point lock relays as stated in Section 15.10
of this standard.
12.2.10. Failure of section control relays in single line track control sections In the event of failure of a section control relay in track controlled areas with pilot working, it may
be permissible to temporarily bridge-out the half pilot staff contacts. This can be done at one or
both ends of the section for testing purposes provided the starting signals at both ends of the
section are booked out of use. A temporary bridging authority shall be issued for this purpose.
12.2.11. Failure or damage to signalling cables and wires When failures are caused by broken or damaged signalling cables and wires, no attempt shall
be made to manipulate any relay or equipment affected by the defect. The affected signalling
shall be booked out of use until the items are effectively repaired.
The work of repairing or replacing signalling cables and wires shall be done in accordance with
Section 19.6 of this standard.
12.3. Temporary repairs Temporary repairs shall be done only where the work does not affect the design principle. The
work shall be done in accordance with Section 19 of this standard, which outlines the specific
requirements for additions, alterations and renewals work, and the level of authority required to
undertake such work. The requirement also outlines the associated risks and lists examples for
mitigation.
The testing of temporary repairs shall comply with the requirements prescribed in SPG 0711.
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
13.4.5. Disconnection of releasing switches and electric lever locks Releasing switches and electric lever locks shall be disconnected to prevent their operation by
electrically isolating the coil operating circuit. A test shall be conducted to ensure that the device
is inoperative.
14. Temporary bridging of signalling circuits The principle for using temporary bridging states that the protection defeated by the bridging is
provided by an effective alternate means.
Temporary bridging of signalling circuits shall be done only in exceptional circumstances as
necessary to minimise disruption to trains caused by signalling equipment that is damaged or is
disconnected or disarranged.
Temporary bridging shall not be connected across any contacts which provide protection for the
movement of trains in either of the following cases:
• where it prevents signalling apparatus from properly returning to a more restrictive position
or locked position
• where it allows unprotected signalling apparatus to operate to a less restrictive or unlocked
position when it is not safe to do so
Temporary bridging of signalling circuits shall be performed in accordance with signalling
safeworking procedures.
Signalling apparatus with temporary bridging applied shall be booked out of use. Safe
arrangements shall be made to secure the apparatus concerned so that it cannot be moved out
of correspondence with the interlocking and the bridged-out position. Signals affected by the
apparatus temporarily bridged shall also be booked out of use except where stated in
Section 14.1.
Temporary bridging shall be confined to bridging of closed contacts of trackside signalling
apparatus that indicate the locked, fail-safe position of the apparatus. For example, the 'Normal'
indicating contacts of signals at stop or trainstops in the raised position or the detection contacts
of points in their correct position and locked. The temporary bridging of contacts shall be limited
only to failed or removed apparatus. Jumper wires shall be connected as close as possible to
the apparatus concerned.
Contacts that are temporarily bridged shall be disconnected so that the work does not interfere
with the live portion of the circuit.
Additionally, where 'Normal' detector contacts are temporarily bridged, for example at an end of
points, the circuits that provide the Reverse detection shall be disconnected. Similarly, if the
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
for the bridging as provided by the authorising signal engineer. The name of the authorising
signal engineer shall suffice until a signature is obtained.
Temporary bridging granted by an approved circuit design shall be performed in accordance
with SPG 0711.
14.2.1. Approval of temporary bridging by authorising signal engineer Where temporary bridging is granted by an authorising signal engineer, it shall be performed in
accordance with a documented process and a temporary bridging authority form stating at least
the following information:
• unique temporary bridging authorisation number
• location and listing of signalling equipment to be bridged
• planned date and time for the application and removal of bridging
• reason for the temporary bridging
• a photocopied diagram of circuits to be bridged
• authorising signal engineer approval (name, signature and date approved)
• the responsible signal engineer's advise (name and date advised)
• person nominated to apply bridging (name, signature, time and date bridging applied)
• identification numbers of jumper wires applied
• person nominated to remove bridging (name, signature and time and date bridging
removed)
• identification numbers of jumper wires removed
• time and date of removal advice provided to authorising signal engineer
• authorising signal engineer final sign-off (signature and date)
The bridging authorisation number shall be noted on the infrastructure booking authority as
stated in the network rules and procedures. Additionally, the word 'BRIDGED' in brackets shall
be written along side each of the equipment listing that has bridging applied.
When booking the affected signalling back into use, signing the infrastructure booking authority
shall constitute certification that all the temporary bridging has been removed and the affected
signalling has been tested to be safe and reliable.
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
• momentarily energising a signal normal indication relay at standard relay interlockings, or a
point lock relay at standard relay interlockings (not route control interlockings), or a signal
route normal lock relay at route control interlockings
• momentarily bridging the track stick contact of the approach stick circuit at standard relay
interlockings or at route control interlockings, or the affected track circuit contacts proving
the track locking element in a point lock relay circuit at route control interlockings
15.2. Requesting a release A formal 'request for release' shall be obtained from the signaller before a manual release is
provided. Details of the release shall be entered in the train register book or other permanent
record or by using an infrastructure booking authority. The details of the release shall be signed
by both the signaller and the licensed signalling person.
The signaller shall be requested to place the associated signals to stop and ensure they remain
at stop by applying appropriate blocking facilities before a release is provided. Licensed
signalling personnel shall also receive an assurance from the signaller (recorded on the request
for release document) that all approaching trains have come to a stand and shall remain so.
A separate request shall be obtained for every release given, requiring either a separate entry in
the train register book or other permanent record or a separate infrastructure booking authority.
15.3. Precautions before releasing normal indication locks on signal levers Normal indication (NI) locks on signal levers incorporate indication locking and track locking for
approach locking and in some cases route holding.
The following precautions shall be observed before providing a release of normal indication
locks on signal levers:
• ensure the associated protecting signals are at stop and the trainstops where provided are
in the raised position
• ensure any train approaching the signal involved has been brought to a stand
• ensure any train occupying track circuits included in the normal indication lock circuit has
been brought to a stand and is clear of any points in the route ahead of the signal
15.4. Precautions before releasing normal/reverse locks on point or facing point lock levers Normal and reverse ('N/R') locks on mechanical point or facing point lock levers incorporate
track locking generally for both approach locking and route holding.
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
The following precautions shall be observed before providing a release of normal/reverse locks
on point or facing point lock levers:
• ensure the associated protecting signals are at stop and the trainstops where provided are
in the raised position
• ensure any approaching train has been brought to a stand
• ensure no train is foul of any of the points worked by the points lever
At hybrid installations containing both mechanical and relay interlocking, ensure that all relay
interlocked functions are non-conflicting with the mechanical interlocking. This shall be done
before a normal or reverse electric lock is released on a point or facing point lock lever.
Where it is intended to by-pass a train occupying route holding circuits with another train, the
licensed signalling person giving the release shall be assured by the signaller that both train
drivers are aware of the intended move.
15.5. Precautions before releasing normal/reverse indication locks on point levers Normal or reverse indication (NI/RI) locks on point levers apply indication locking and do not
incorporate track locking.
The following precautions shall be observed before providing a release of normal/reverse
indication locks on point levers:
• ensure the points are lying in correspondence with the point lever and the point switch
blades are in their respective fully closed/fully open positions as applicable, and that facing
points where provided are securely locked by the point lock
• ensure the points will not be unlocked or moved before giving the release - if necessary clip
and SL lock the points
Points that remain out of use following an initial release of the indication lock shall not be
released again unless the points are booked out of use, clipped and SL locked. The failed
indication lock may then be permanently released if necessary. This is done to enable the lever
to be placed in correspondence with the points position in order to obtain the sequence of the
interlocking.
Rail traffic shall not be permitted to pass over facing points while the point lever is in the NI or RI
position; unless the points are secured by clip and SL lock.
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
15.6. Precautions before releasing point lock relays at standard relay interlockings Point lock relays in standard relay interlockings apply track locking, generally for route holding
and in some cases approach locking.
The release of point lock relays at standard relay interlockings may be provided except in cases
of track locking (approach locking). Such approach locking is released by the approach stick
relay.
The following precautions shall be observed before providing a release of point lock relays at
standard relay interlockings:
• ensure the associated protecting signals are at stop and the trainstops where provided are
in the raised position
• ensure any approaching train has been brought to a stand
• ensure no train is foul of any points worked by the points control
Where it is intended to by-pass a train occupying route holding circuits with another train, the
licensed signalling person giving the release shall be assured by the signaller that both train
drivers are aware of the intended move.
15.7. Precautions before releasing signal normal indication relays at standard interlockings The release of signal normal indication relays at standard relay interlockings may be provided
except in cases of track locking (approach locking); such approach locking shall be released by
the approach stick relay.
The following precautions shall be observed before providing a release of signal normal
indication relays:
• ensure the associated protecting signal is at stop and the trainstop where provided is in the
raised position
• electrically disconnect the associated signal to prevent its operation
• ensure any train approaching the signal involved has been brought to a stand
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
15.8. Precautions before releasing approach stick relays Approach stick relays are provided for approach locking of signals that protect points.
The following precautions shall be observed before providing a release of approach stick relays:
• ensure the associated protecting signal is at stop and the trainstop where provided is in the
raised position
• ensure any train approaching the signal involved has been brought to a stand
15.9. Precautions before releasing signal route normal relays at route control interlockings The release of signal route normal relays at route control interlockings may be provided except
in cases of track locking (approach locking); such approach locking shall be released by the
approach stick relay.
The following precautions shall be observed before providing a release of signal route normal
relays:
• ensure the associated protecting signal is at stop and the trainstop where provided is in the
raised position
• electrically disconnect the associated signal to prevent its operation
• ensure any train approaching the signal involved has been brought to a stand
15.10. Process for releasing route holding in point lock relay circuits at route control interlockings In route control interlockings, point lock relays incorporate interlocking functions and shall not be
released except in the following cases and only as permitted by a signal engineer:
• a failure occurs of the track locking element in a point lock relay circuit
• the route holding tracks are occupied by a failed rail vehicle
In these cases, the release of track locking shall be performed in accordance with the process
for energising the applicable point lock relay. This process allows the point lock relays to be in
correspondence with the intended lie of the points. The specific release details shall be fully
explained to the signaller.
The following process shall be observed to provide a release of route holding in point lock relay
circuits at route control interlockings:
1. ensure all signals that interlock with the points are at stop and the trainstops where
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
2. ensure any train that has entered the route concerned has come to a stand
3. ensure any points or releases which interlock with the points concerned are in non-
conflicting positions
4. ensure no train is foul of the points concerned
5. instruct the signaller to operate the point control to the position in correspondence with the
current lie of the points (and the interlocking) and apply a block to the point control
6. manually operate the points concerned to the intended (opposite) position and secure by
clip and SL lock (this will temporarily place the points out of correspondence with the
interlocking and point control)
7. momentarily bridge the appropriate track locking relay contacts in the relevant point lock
relay circuit and instruct the signaller to operate the point control to the centre position and
observe the points 'free' indication
8. instruct the signaller to operate the point control to the intended position (normal or
reverse) in correspondence with the lie of points
9. remove the bridge immediately upon the respective point lock relay becoming energised
10. check that the opposite point lock relay is in the de-energised position
No attempt shall be made to operate the point lock relay or points by operating route set
buttons.
Contacts in the point lock relay circuit, other than those applying track locking, shall not be
bridged.
Point lock relays shall not be manually lifted or replaced with a relay in the 'energised' position.
Where it is intended to by-pass a train occupying route holding circuits with another train, the
licensed signalling person giving the release shall be assured by the signaller that both train
drivers are aware of the intended move.
15.11. Providing releases for other situations including computer based interlocking Other situations may arise when the signalling interlocking has been locked and may require a
release. An example of this is at computer based interlockings where a loss of track circuit input
may cause the interlocking to be locked.
In such cases, where the procedures for providing a release are not prescribed by this standard,
the risks of providing such a release shall be first identified by a signal engineer.
The decision to release the signalling interlocking shall be decided by the signalling engineer
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
Points affected by seldom use for a period greater than nine weeks shall be clipped, XL locked
and spiked.
Points that are inoperable or have other constraints due to seldom use shall be listed at the
relevant signal box.
The portion of a turnout that is rarely used forming part of a run-off not governed by a signalled
approach may be exempt from 'seldom used' requirements and the points may be left
operational.
Where seldom used points become impractical to operate for maintenance purposes and the
points are booked out of use, the maintenance may be reduced to the specific tasks stated in
Section 16.1.4 of this standard.
16.1.1. Specific requirement for emergency crossovers Emergency crossovers, whether operated by ground frames released by a releasing switch,
duplex lock or similar arrangement, shall be clipped and XL locked in the normal position when
the emergency crossover is not in use.
16.1.2. Points at sidings or refuges operated from a ground frame or adjacent control panel Points at sidings or refuges operated from a ground frame or adjacent control panel may remain
operational where the operator can clearly observe the clearance point or other end of points.
16.1.3. Installed points pending commissioning or removal Where a set of points is installed pending proper connection to the interlocking or where the
interlocking is removed from points pending removal, the point switch blades shall be
adequately secured in accordance with ESG 100 Signal Design Principles.
The periodic maintenance of point securing devices for points not properly connected to the
interlocking shall be scheduled as if they were operational points. The maintenance tasks shall
be performed in accordance with Section 16.1.4 of this standard.
The checking of XL locks, point-clips and point-spikes used to secure installed points that are
not connected to the interlocking shall be included in the signal engineer's periodic testing of
signalling interlockings in accordance with Section 27.4.
16.1.4. Specific maintenance tasks where points are impractical to operate due to seldom use Where it is impractical to operate points for maintenance purposes due to seldom use, the
specific tasks listed below shall be scheduled at the same frequency as operational points.
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
effective track shunt, before the 72 hour period commenced. Where the rail condition is in a
lesser state, then consideration to reduce the 72 hour period nominated in the network rules
and procedures may be proposed as an exception to the general requirement. In such cases,
the exception shall be documented and duly issued to the designated network control officer
and relevant signalling personnel.
In certain circumstances, the responsible signal engineer may deem it acceptable to extend the
72 hour period, conditional upon an assessment of the engineering risks and operational
implications being appropriately mitigated. The determination shall take into account the factors
for consideration stated in Section 16.2.3 of this standard. The matter shall then be raised for
acceptance with the signal engineer holding accountability on behalf of the operator/maintainer
and the appropriate network control officer.
16.2.2. Identifying and testing track circuits at risk Where rail traffic has stopped operating for periods greater than 72 hours affecting large areas
of track circuited lines, suitable arrangements shall be put in place to identify and test the track
circuits at risk.
Periods of non-use may be instigated by possession work, industrial dispute, alteration to
normal timetables or varied freight operations.
Proper and timely notification, liaison and planning with the relevant parties are required to
ensure that risks associated with loss of track shunt are managed effectively so as to not cause
a reduction in signalling safety.
Examples of trackwork or possession situations which may cause track circuits to be at risk of
not providing an effective track shunt include the following:
• track circuits directly worked on during trackwork (example: installation of new or rusty
rails)
• track circuits inside a possession area that are not part of any trackwork
• track circuits outside a possession area that are not traversed due to an operational
variance caused by the possession
An inspection and test plan shall be arranged as part of a strategy for testing track circuits for an
effective track shunt following periods of non-use greater than 72 hours.
The method and scope of testing shall vary depending upon the reason for the event, length
and track configuration, type of trains in operation, weather conditions and the period of
non-use.
Testing strategies may require re-evaluation if the scope of work or possession arrangements
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
17. Requirements for re-railing and associated trackwork When re-railing is performed that involves breaking the rails of track circuited or electrified lines,
certain elements shall be considered to ensure all the risks associated with the work are
understood and controlled. These considerations shall include the following elements:
• protection of trains
• provision of alternative traction return
• testing of track circuits and associated signalling
• ensuring an effective track shunt
• certification of infrastructure for operational use
Note: For the purpose of this standard, re-railing includes any trackwork that involves
breaking the rail.
17.1. Licensed signalling personnel attendance Licensed signalling personnel shall attend re-railing when it occurs in any of following situations:
• within interlocked areas, except where outer home signals are provided and the intervening
track circuits do not impact the operation of the interlocking
• in the vicinity of points located at intermediate sites outside an interlocking
• in plain track areas where the length of re-railing is six metres or more
• at any location on electrified single lines
• in the vicinity of insulated joints, tuned loops or any other track interface, including short
sections of rail in the vicinity of converging track clearance points
• adjacent to substations or sectioning huts
• wherever there is potential for traction bonding or track circuit cabling to be interfered with
by the work
In all other cases, licensed signalling personnel may be exempt from attending re-railing. In
such cases, temporary rail bonds shall be issued by signalling personnel to qualified track
workers for them to apply. This is done to allow the trackwork, which would otherwise affect
operational signalling, to proceed with minimum disruption to rail traffic. The track circuits
remain operable by the placement of temporary rail bonds around the rail break. Temporary rail
bonds and their placement shall be in accordance with the requirements stated in Section 17.7
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
same time. For example, it is permissible to have a break in both (opposite) rails of a track
simultaneously, but no other breaks can be made at that time.
18. Requirements for providing adequate traction return Adequate provision for the safe return of traction return current shall be considered and
implemented before performing work that affects its path to the substation or section hut.
The following types of work have the potential to impact the return path of overhead traction
current:
• re-railing in electrified areas
• disconnection of traction bonding including impedance bonds
• disconnection of negative return cables at substations and section huts
Alternative traction return arrangements shall be made to mitigate the risks associated with rail
breaks, disconnected traction bonds or negative return cables. This is done to ensure unsafe
voltages do not develop across the rails or cables.
Similarly, signalling equipment shall be safeguarded against damage caused by the potential
rise in traction return voltage.
In many cases, particularly where complete tracks are removed, the alternative arrangements
may include isolation of the overhead. Where this is the case, the effects of live overhead that
may be adjacent to the isolated section shall be considered.
18.1. Exemption to providing alternative traction arrangements Implementing alternative traction arrangements may be exempt in certain circumstances on the
following conditional requirements:
• ensure traction bonding in the vicinity (on both sides) of the intended work complies with
the specific track insulation plan
• ensure traction bonding in the vicinity has sufficient capacity to safely return the additional
traction return current
These conditions shall be validated by physical inspection of the traction arrangements to
confirm their condition and compliance.
Where the exemption applies, only one rail break shall be permitted in each traction rail.
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
The following circumstances state where the exemption from providing alternative traction
arrangements may apply:
• On lines where there are three or more traction rails in the same corridor that provide the
traction return path to a substation or section hut. In this case, one traction rail may be
broken without providing alternative traction arrangements.
• On lines where there are six or more traction rails in the same corridor that provide the
traction return path to a substation or section hut. In this case, two traction rails may be
broken without providing alternative traction arrangements.
18.2. Work affecting negative return at substations or section huts Where re-railing, or disconnection of traction or negative return cables is done adjacent to
section huts or substations, at least one effective negative return cable shall be retained during
the work. This is to ensure unsafe voltages do not develop across rail or cable breaks.
The following requirements shall be met for undertaking re-railing, or disconnecting traction
bonding or negative return cables adjacent to substations or section huts, as applicable:
• Where substation or section hut negative return cables connect to both sides of a
mechanical joint in single rail track circuits, the re-railing shall be done in two stages. The
first stage shall include re-railing only to one side of the mechanical joint. After the negative
return cable of that portion is reinstated, the remainder of the re-railing shall be carried out
as the second stage.
• Where substation or section hut negative return cables connect to plain rail (no mechanical
joint) in single rail track circuits, the rail shall be first cut so both negative return cables are
not disconnected simultaneously. The first stage shall include re-railing only to one side of
the rail cut. After the negative return cable of that portion is reinstated, the remainder of the
re-railing shall be carried out as the second stage.
• Where substation or section hut negative return cables connect to impedance bonds in
double rail track circuits, the re-railing shall be undertaken on only one rail at a time. During
this time, the other rail shall remain fully bonded with its negative return made via the
impedance bond.
Where the above requirements are impractical, the overhead traction shall be first isolated
before commencing the work. For example, when the complete track is required to be removed.
The electrical operation control centre shall be notified of the intention to disconnect any
substation or section hut negative return cables before the work commences.
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
18.3. Work affecting impedance bonds Before an impedance bond is disconnected, the feed and relay of the affected track circuit shall
be isolated from the track. Temporary bonding shall be provided for the traction return path
between the affected track circuit and the adjacent track circuit traction path.
18.4. Temporary rail connections for overhead wiring Temporary rail connections are permitted for temporary earthing of overhead wiring. This shall
be in addition to permanent rail connections where these are provided in accordance with
signalling designs for installed overhead sectioning and earthing switches.
When temporary rail connections are requested, a signal engineer shall nominate the location
for the connection and provide a marked-up copy of the specific track insulation plan. The
connection shall be made only on the traction rail of a single rail track circuit or the neutral point
of a double rail track circuit. Where the operation of the track circuit is not required, the
connection may be made on any of the traction rails.
In cases where the operation of a track circuit is affected by the temporary earth connection, the
track circuit shall be disconnected and the associated signalling shall be booked out of use.
Temporary rail connections shall be made by a secure connection and located clear of any
trackwork taking place.
19. Minor signalling additions, alterations and renewals work Sustaining the integrity of the operating signalling system at all times is an unconditional
requirement. This is particularly relevant during signalling additions, alterations and renewals
work where the risks from interference caused by the work are increased.
Note: Alteration work includes the installation of any temporary repairs.
All persons performing such work shall be aware of the potential impact of the work they
perform, including the effect on adjacent running lines or operational equipment in close
proximity to the work area. Signalling that has been tested and certified, pending being brought
back into use, shall be secured and treated similarly as if it were operational equipment.
Any work which has the potential to impair the integrity of the signalling shall be booked out of
use, including the signals in the rear of the affected equipment.
Work on signalling equipment which involves disconnection, disarrangement, disassembly,
adjustments, alterations or additions shall be planned and performed with adequate controls in
place. This shall include thorough testing at the completion of the work commensurate with
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
assembly, incorrect type or configuration, improper adjustment and so on. This shall be
assessed and then mitigated by suitable testing in accordance with SPG 0711.
A functional test of the apparatus shall always be included in such testing.
19.1. Risk mitigation requirements for minor additions, alterations or renewals Risk mitigation requirements for minor additions, alterations or renewals shall be prescribed in
signalling safeworking procedures.
The following are examples of risk mitigation requirements to be included in signalling
safeworking procedures for minor additions, alterations or renewals, as applicable:
• electrically isolate the live circuitry of affected signalling from the worked-on portion
• correlate the existing arrangement, which includes apparatus inspection, wire and null
count to ensure it reflects the specific as-built design before commencing work
• ensure the signalling documentation used reflects the latest design
• secure and insulate unterminated wires, including spare cable cores in such a way that
they are unable to make contact with any conductive surface or electrical component
• not connect wires or equipment pending commissioning to working circuits, and as such
shall require two points of connection to take effect
• not leave connected wires and equipment decommissioned from use, to working circuits or
power supplies
• label and tag wires and corresponding terminals before connecting or removing
• treat metal links as wires, particularly when wire/null counting
• disconnect and reconnect only one single wire or one cable type (where the individual
cores can be easily identified) at a time, where possible
• mark matching sides of equipment including air hoses before disassembly
• provide a unique and distinct colour for temporary wiring used on each stage or testing
purpose
• comply with the required standard for the specific location including wires, cable cores,
contacts and other items of equipment which will be utilised in new or altered circuits
• update accordingly, the signalling documentation at the end of each stage
• ensure personnel are competent for the task
• comply with the testing and certification requirements of SPG 0711
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
• ensure adequate lighting and access
• remove distractions or causes of pressure
• apply a methodical and systematic approach
• maintain proper housekeeping of the work area and ensure the housing and all equipment
are made secure when vacated
19.2. Involvement of signal engineer for risk mitigation requirements A signal engineer shall be associated with every signalling addition, alteration or renewal. The
level of association shall be dependent upon the risks associated with the work and the
authority level of the signalling personnel performing the work, which includes inspection, testing
and certification.
Examples of such cases are listed below:
• signal engineer signs off the scope and authorisation form for a like for like renewal
• signal engineer authorises a like for like renewal where the equipment is not exactly
identical
• signal engineer is advised of rewiring
• signal engineer performs inspection and testing of signalling additions or alterations
• the responsible signal engineer is consulted when adjustment made beyond specified or
expected limits
• the responsible signal engineer consulted when temporary repairs are effected
• the signalling commissioning engineer commissions new or altered signalling
19.3. Work not affecting the design principle Licensed signalling personnel are permitted to perform some alteration work on the signalling
system, without the direct involvement of a signal engineer, where the work does not alter the
design principle. The following are the tasks that can be performed by licensed signalling
personnel:
• Transfer of a circuit from a defective contact, terminal, cable core or wire to an equivalent
spare in order to rectify a failure scenario. The wiring work shall be limited to removing one
single wire or cable type at a time. This work shall be treated as a temporary repair in
accordance with Section 12.3 of this standard.
• Replacement of signalling equipment with an identical type. The like for like renewal
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
• shelf relay replaced by a plug-in relay conversion unit
• partial renewal where not all elements are replaced and only a subset of the work
instruction may be applicable
• where a work instruction does not cater for the particular type of work
Where an authorisation is granted, the scope of work and authorisation form shall include a
description of the difference between the equipment types and a listing of any subsequent
actions. The subsequent actions can include updating the asset register, marking-up and
signing the field certified office copy, submission of the certified office copy for updating, and
arranging additional training for signalling personnel. Any pending actions following the
authorised renewal of not exactly identical equipment shall be promptly closed out.
Additionally, the scope and authorisation form shall be signed by the signal engineer before
commencing the work. In cases of emergency, the signal engineer may provide the
authorisation remotely, and provide the signature at the earliest opportunity.
19.4.3. Granting pre-authorisation for like for like renewal work A signal engineer may consider pre-authorising routine equipment changes in advance of an
event. The pre-authorisation shall be documented by providing appropriate local procedures
attached to the relevant work instruction. The local procedures shall mitigate the additional risks
associated with the equipment difference.
The following are examples where pre-authorisation may be granted for a like for like renewal:
• newer version of equipment replaces an earlier version (including trainstops and point
machines)
• a point machine is changed on a triple-end or at independent switches
• shelf relay replaced by a plug-in relay conversion unit
19.5. Work affecting the design principle Additions, alterations, or renewal work that do not meet the like for like renewal requirements, or
any other work that affects the intended signalling design principle or configuration shall
proceed only when issued with an approved design. Approved designs are issued by the
contracted AEO accountable for approving signalling design. A signalling commissioning
engineer shall be assigned to lead this work and the work done in accordance with SPG 0711.
The following are examples where work shall be treated as an alteration, done in accordance
with SPG 0711, and not as a like for like renewal:
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
19.6.1. Additional testing requirements for specific situations In addition to the normal testing requirements stated in SPG 0711, the requirement of specific
testing shall be included in signalling safeworking procedures to mitigate risk that pertain to the
situations stated below:
Signalling cables damaged by excavation works
Where multi-core cables are damaged by excavation works or similar, there is a risk that the
insulation between the conductors can get damaged. This can cause a short circuit current flow
over a sustained period which can lead to deformed Q type relay contacts.
Where the sustained short circuit period exceeds one hour, a signal engineer shall consider the
consequential risk of the sustained short circuit current flow. If determined necessary, the signal
engineer shall mandate, in addition to the normal testing requirements, the testing of all relay
contacts in the affected circuits on the fuse or supply side of the damaged cable. This testing
shall be conducted by either of the following two methods:
• test the affected relay in a relay test panel to ensure all contacts operate (open and close)
in accordance with their configuration type
• functionally operate the relays in the affected circuits to ensure that they are effective in
each circuit function as designed (circuit function test)
Track circuit wires replaced
Licensed signalling personnel are permitted to repair or replace two or more track circuit leads
to a track circuit location by changing over one single wire or associated pair at a time.
The work shall be tested to ensure the following:
• wires have not been cross connected
• track circuit relay de-energises with the correct shunt applied across the rails
• polarity of the track circuit, where applicable, is in accordance with the track insulation plan
A shunt test of adjacent track circuits shall also be performed.
Where cut tracks are involved, a shunt test shall be performed to ensure the track voltage of the
adjacent cut track is removed during the shunt.
Signalling data communication links replaced
Data communication links are utilised to connect vital and non-vital systems such as Microlok II,
Solid State Interlocking, Dupline, Kingfisher, SCADA and other such systems. These links
consist of either copper communication type cables or optical fibre conductors.
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
When changing a spare pair in a copper communication type cable or optical fibre conductor,
the logically correct pair at both ends shall be first established, followed by an end-to-end
continuity test, before certifying the signalling back into use.
19.7. Documents used for the certification of signalling Except as provided for in the like for like renewal requirements, provision for the certification of
signalling shall be achieved by completion of the following signed documents as applicable:
• infrastructure booking authority
• interlocking certificate, design integrity test certificate
• maintenance record; for example, point lock return, insulation test record, track circuit
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
accountable for providing the maintenance. Returns shall be duly submitted to the responsible
signal engineer for review of the certification and compliance elements and actioning any
necessary items.
An additional return shall be required for any out of course safety critical or safety significant
adjustment or test made between periodic maintenance inspections.
Other such records, for example, relay records, battery records, track circuit records, insulation
test records, signal inspection and test records shall be kept on-site as applicable and also with
the responsible signal engineer or maintenance depot.
20.3.1. Maintenance schedule period latitudes The signalling technical maintenance plan defines the tasks and schedules for signalling
infrastructure maintenance. Maintenance frequencies shall comply with the frequencies stated
in the signalling technical maintenance plan and this standard where defined for safety critical
and safety significant tasks. Each task may have a planning latitude which reflects the permitted
variation around the task due date. Planning latitudes shall be no greater than 20% for tasks
with a frequency of up to 42 days, and no greater than 10% for tasks with a frequency of above
42 days, unless authorised by the ASA.
Safety critical and safety significant tasks shall be completed within the defined planning
latitude.
Safety critical and safety significant tasks not achieved by the due date and latitude period shall
be risk assessed by the responsible signal engineer and the risks appropriately and promptly
mitigated. Failure to secure prompt appropriate risk mitigation shall warrant the particular asset
and associated assets to be booked out of use.
The non-compliance of other signalling maintenance tasks that are not safety critical or safety
significant shall be managed in accordance with the contracted AEO's engineering management
system. However the risks associated with the safety elements of these tasks shall be
considered and prioritised by the responsible signal engineer.
21. Inspection and testing of vital signalling relays Vital signalling relays are integral to the safety and reliability of interlockings. Their critical
applications include control, indication, locking, operation, detection and timing. The safety
assurance aspect of vital signalling relays requires a thorough understanding and management
of the various failure modes and associated risks. Persons working on vital signalling relays
shall take the necessary precautions when wiring, inspecting and maintaining, replacing, and
overhauling. These safety assurance requirements shall be included in signalling safeworking
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
Vital signalling relays exist in various forms and configurations, but all are categorised as either
proved (proved in the de-energised position by the signalling design) or unproved. Unproved
relays pose a greater risk, as a wrong side failure associated with these relays may go
undetected by the system.
All vital signalling relays shall be supplied sealed to prevent unauthorised tampering. Any vital
signalling relay in service that is not sealed shall be treated as sealed and not opened. The seal
shall not be broken in the field except in exceptional circumstances and only as directed by a
signal engineer.
Plug-in conversion units, using Q type BRB 930 relays, are available as a replacement for ACVL
relays and any ACVL relay determined for replacement shall be replaced with the conversion
unit. For each replacement, a notice of installation advice shall be completed and submitted for
the purpose of circuit book update. Once installed, the conversion unit may be considered as a
plug-in relay for maintenance purposes.
Note: Conversion units have a contact current capacity of only three amperes.
21.1. Precautions and requirements for vital signalling relays Precautions and requirements for vital signalling relays shall be prescribed in signalling
safeworking procedures.
The following are examples of precautions and requirements for vital signalling relays:
• Vital signalling relays shall be inspected and tested before they are placed into service for
correct operation and configuration (voltage, type, contact configuration, and coding) in
accordance with the specific signalling design. The relay shall also be closely inspected for
any transit damage.
• The tampering of coding holes in bases or coding pins in relays is strictly forbidden.
• The signalling associated with circuits that pass through shelf relays that are not fitted with
a detachable top shall be booked out of use before replacing.
• The circuits that pass through replaced relays shall be functionally tested. Any wiring
disturbed shall be wire and null counted.
• The replacement task of shelf relays shall be wholly performed by one person and not
transferred to another person part way through the work.
• The change details of replaced shelf relays, VT1 relays, electro-mechanical and thermal
timer relays, and large plug-in relays shall be duly recorded and a notice of relay change
submitted to the responsible signal engineer.
• Relay wiring shall not be altered contrary to the specific signalling design unless
transferring to a spare contact for the purpose of temporary repair during failure situations.
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
• dc shelf relays – five years
• ac shelf relays – three years
New Q type BRB 930 relays, stored in original packaging may be exempt from re-testing
requirements subject to the relays passing a visual inspection and operation in a conventional
relay test panel (which indicates relay contact status).
Used Q type BRB 930 relays with up to 10 years service may be considered for reuse, on
condition that the relay is inspected to be in proper condition (including seals intact, coding pins
straight, plug in contacts not bent, no evidence of corrosion or foreign matter, and transparent
cover). Additionally, the relay shall pass a functional test in an approved relay go/no-go tester.
Q type BRB 930 relays with a contact resistance greater than 2 ohms shall not be used except
in cases of emergency, as a temporary measure, on condition that the resistance is not greater
than 7.5 ohms. In such cases, temporary repair requirements in accordance with this standard
shall be complied with.
21.3. Maintenance and overhaul of vital signalling relays The periodic inspection of unproved vital signalling ac vane and dc shelf relays shall be treated
as a safety critical task in accordance with Section 20.2 of this standard.
The testing of electro-mechanical and thermal type timer relays shall be treated as a safety
significant task in accordance with Section 20.2 of this standard.
The replacement for overhaul of unproved ac vane and dc shelf relays shall be treated as a
safety significant task in accordance with Section 20.2 of this standard.
Any vital signalling relay, including spare relays, found with a defect having potential to impact
on its safe operation shall be promptly brought to a signal engineer's attention and the signalling
shall be protected accordingly.
21.3.1. Inspection requirements for ac vane relays (all types)
AC vane relays shall be periodically inspected for abnormal operation in accordance with the
signalling technical maintenance plan. However, the period between inspections shall not
exceed 52 weeks.
The following inspection criteria for ac vane relays shall be included in signalling safeworking
procedures:
• ensure correct operation, condition of contacts, terminals and pigtails
• inspect for correct release (not sluggish or jerky) and not failing to return fully to the stop
position due to defective bearings, warped bakelite tops, wax or other foreign matter in the
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
21.3.3. Inspection requirements for large plug-in and Q type BRB 930 relays Large plug-in and Q type BRB 930 relays shall be periodically inspected for abnormal operation
(to the extent practical without removal) in accordance with the signalling technical maintenance
plan. However, the period between inspections shall not exceed 52 weeks.
The following inspection criteria for large plug-in and Q type BRB 930 relays shall be included in
signalling safeworking procedures:
• ensure clear plastic covers not fouling the contact assembly due to warping or cracking
• inspect for contact burning, or pitting of the carbon contacts
• inspect for displaced or worn carriers
• inspect for rust on plated components or signs of excessive deterioration of the plating
• ensure retaining clip is securing relay in base
21.3.4. Inspection requirements for time limit relays
Electro-mechanical and thermal type timer relays shall be periodically tested for the correct
time-out duration (not exceeding 10% of the specified time) and operation in accordance with
the signalling technical maintenance plan. However, the period between inspections shall not
exceed two years.
Electronic time limit relays such as QTD5 or similar may be exempt from periodic testing.
21.3.5. Replacement requirements for vital signalling relays The procedure for shelf relay replacement shall be in accordance with the like for like renewal
requirements as prescribed in this standard.
Unproved ac vane and dc shelf relays shall be periodically inspected and overhauled in
accordance with the signalling technical maintenance plan. However, the period between
overhaul shall not exceed 15 years, except for relays used on cut-tracks which will not exceed
10 years.
Proved ac vane and dc shelf relays and other relay types shall be replaced on a needs basis.
Samples of Q type BRB 930 relays from typical installations shall be inspected after 20 years in
service to assess the need for replacement. The inspection shall be performed in suitable
workshops by persons competent to do so, jointly with licensed signalling personnel. A report of
the sample relays inspected shall be compiled and sent to the responsible signal engineer for
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
All vital signalling relays shall be fitted with suitable labelling to identify the relay as overhauled.
The label shall include relevant information such as the date of overhaul, workshop and tester's
identification and any specific values pertaining to the relay type.
21.3.6. Programming the replacement and overhaul of vital signalling relays The responsible signal engineer shall have an effective program for the replacement and
overhaul of vital signalling relays as required by this standard. The program shall include
relevant details of ac vane and dc shelf relays in service. The program shall also include details
of ac vane and dc shelf relays that were replaced due to defect or periodic overhaul.
21.3.7. Treatment of safety related relay faults Any vital signalling relay that fails to de-energise, or falsely indicates an energised or
de-energised state, or has a fault which may impact upon the safety of the signalling system
shall be immediately protected in accordance with signalling irregularity requirements as
prescribed in this standard. The relay shall not be initially disturbed. The responsible signal
engineer shall be promptly advised to provide further instruction. The failure and investigation
shall be treated as a signalling irregularity.
Vital signalling relays identified with defects shall be analysed jointly by a signal engineer and a
relay manufacturer or overhaul expert in a suitable workshop environment. The pending actions,
including the addressing of any potential effects for similar relays in service or spares, shall be
promptly attended to and closed out.
22. Inspection and testing of signals and signs Signals and signs referenced in this standard are those shown on signalling plans, track plans
and working sketches. These are viewed by train drivers or by users at level crossings for the
purpose of safeworking and operation of the railway.
Signals display either a colour light or semaphoric indication. Signs may be passive,
retro-reflective or active.
Running signals shall be maintained to display the optimal indication from the lens system and
the applicable sighting of the indication shall be as long and continuous as practical.
The focus of signals shall be maintained not to cause an ambiguous or read-through indication.
The door of colour light signals shall not be opened where the risk of light penetrating through
the open lamp case, can affect approaching trains (causing an irregular signal indication).
Signal doors shall be checked to ensure they are securely closed and locked before leaving the
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
22.1. Requirements for periodic and responsive signal sighting Signals and signs shall be periodically inspected and maintained for optimum visibility and
acceptable sighting distance in line with signalling design principles. The frequency of this work
shall be in accordance with signalling technical maintenance plans and whenever the
opportunity exists during the course of other site visits.
An inspection of sighting for obstructions shall include vegetation growth, new or altered
structures, and changes to the background and lighting conditions, whether on or off the rail
corridor. Any pending actions from these inspections shall be promptly addressed.
In difficult cases where the signal indication cannot be distinguished due to sunlight shining
directly onto the lenses, the responsible signal engineer shall be notified to provide an
appropriate solution. Any configuration change required in this regard shall be approved by the
contracted AEO accountable for approving signalling design.
For Type F and passive type level crossing signals and signs, similar action is required to
ensure that road and pedestrian users receive good sighting of the level crossing lights and
signs. The signal focus and intensity shall be checked as part of periodic maintenance. This will
necessitate viewing the signals on all approaches to the level crossing from a distance in
accordance with signalling design principles.
Running signals shall be regularly checked from the driver's cabin by a signal engineer or other
competent representative for correct focus, optimum light intensity, sighting obstructions, and
the potential for phantom or ambiguous indications. The inspection also provides an opportunity
to liaise with the driver to obtain their perspective of the signal sighting and shall preferably be
done in collaboration with a lead train crew representative.
The signal sighting inspection shall be conducted in accordance with the signalling technical
maintenance plan. However, the period between inspections shall not exceed 26 weeks on
passenger lines and 52 weeks on non-passenger lines.
Where a phantom signal indication is possible, arrangements shall be made to have
anti-phantom filters fitted to the lens modules concerned.
The lights displayed by mechanical signals shall be checked at night while colour light signals
shall be checked during daylight.
Where a signal sighting committee is formed to review the sighting of a signal due to a SPAD or
other sighting issue, the committee shall use the signal sighting checklist and compile the signal
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
Level crossing lamp voltages shall be measured with the level crossing battery supply operating
with the charger turned off.
To maximise lamp life, the lamp voltage shall be adjusted towards the minimum voltage.
Table 1 provides the maximum and minimum voltage settings for signal lamps.
Table 1 - Signal lamp settings
Lamp rating Maximum setting (volts)
Minimum setting (volts)
10 volt 5 watt 9. 7 9.4
10 volt 11 watt 9. 7 9.4
10 volt 13/3.5 watt 9. 7 9.4
10 volt 18 watt 9.5 9.0
10 volt 18/3.5 watt 9.5 9.0
10 volt 25 watt (level crossing lights)
9.7 9.4
12 volt 2/2 watt 10.7 9.0
12 volt 24/24 watt 11.7 / 11.5* 11.3 / 11.1*
12 volt 24/24 watt (subsidiary and marker lights)
10.7 / 11.3+ 10.2 / 11.1+
12 volt 36 watt 11.2 10.7
12 volt 36 watt (subsidiary lights)
10.1 9.5
120 volt 15 watt busbar value busbar value
130 volt 60 watt busbar value busbar value
* applies to lamps where separate voltage taps are not provided for the main and auxiliary filaments and the auxiliary filament is not subject to voltage drop across the filament changeover relay coils
+ applies to lamps in Solid State Interlocking installations
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
24.2. Prerequisite tasks for point testing Certain tasks are required to be done as a prerequisite to point lock testing and point detection
testing. These are done to confirm the satisfactory condition of the various elements before
testing for certification.
The following are examples of prerequisite tasks required before point testing:
• checking the layout for excessive movement that may alter the correct track gauge,
including any excessive lateral movement of switch and stock rails
• checking the stock and switch rail conditions for rail overflow and evident rail defects
(including rail surface defects) that may affect the integrity of the turnout
• cleaning and lubricating, as applicable, the switch plates and switch rollers (where fitted) to
remove contaminants and permit uninhibited operation of the switch rails
• checking the switch plates or rollers for even loading from switch rails
• checking the back-drive equipment (where fitted) for correct and smooth operation
24.3. Requirements for point lock testing mechanically operated points Mechanically operated points shall be tested to ensure the closed-switch cannot open by
3.2 mm or more. This requirement shall be reliant on achieving the following conditions:
• completion of the prerequisite tasks described in Section 24.2
• the point switches lying in correct position
• the point lock has fully entered
The point lock shall not enter if the closed-switch is open by 3.2 mm or more.
For reliability, the point lock shall be adjusted to fully enter with a closed-switch opening of at
least 1.6 mm.
Each open-switch opening (at the switch-tip) shall be checked and adjusted if necessary, in
accordance with their respective point type specification.
The rear flangeway clearance of each open-switch shall be checked to have sufficient
clearance. Any event causing the rear flangeway clearance to become altered (example, worn
switch rail, loose back-drive nuts, bent rodding) shall be suitably tested to ensure the clearance
is to specification.
The point lock plunger travel shall be 200 mm, except in cases where double lock plungers are
worked by one lever the travel shall be 175 mm. When the point lock plunger is withdrawn, the
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
clearance between the end of the lock plunger and the slotted lock rod or the locking rod block
shall be 20 mm.
24.3.1. Other requirements for mechanically operated points On mechanically operated catch points, a fully entered point lock shall not permit the
open-switch to close by less than 100 mm. Additionally, the point lock shall not enter if the
open-switch is open by less than 100 mm.
On mechanically operated points fitted with a wide cut notch point lock for the trailing-only
switch, the point lock specification may be exceeded. In this case a fully entered point lock shall
not permit the closed-switch to open by 6.4 mm or more. Additionally, the point lock shall not
enter if the closed switch is open by 6.4 mm or more. Refer to Section 24.6.2 for requirements
that relate to the provision of wide cut notch point locks.
On mechanically operated points fitted with point lock detectors, the point lock shall enter into
the slide notch with sufficient clearance on both sides. Where a wider notch is used in point lock
detectors (example: at Lithgow), the point lock settings may be altered so that the point lock
does not enter with a closed-switch opening of 4.8 mm or greater. However, the point lock shall
fully enter with a closed switch opening of 3.2 mm or less.
24.4. Requirements for point lock testing power operated points Power operated points shall be tested to ensure the closed-switch cannot open by 3.2 mm or
more. This requirement shall be reliant on achieving the following conditions:
• completion of the prerequisite tasks described in Section 24.2
• point switches lying in correct position
• point lock has fully entered
The point lock shall not enter if the closed-switch is open by 3.2 mm or more.
For reliability, the point lock shall be adjusted to fully enter with a closed-switch opening of at
least 1.6 mm.
Each open-switch opening, at the switch-tip, shall be checked and adjusted if necessary, in
accordance with their respective point type specification.
The rear flangeway clearance of each open-switch shall be checked to have sufficient
clearance. Any event causing the rear flangeway clearance to become altered (example, worn
switch rail, loose back-drive nuts, bent rodding) shall be suitably tested to ensure the clearance
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
24.5.1. Requirements for detection testing mechanisms where detection is interlocked with point lock On some point mechanisms the point detection is interlocked with the point lock, such that the
point lock is required to enter before enabling the detector contacts to close.
In these cases, the point detection setting shall be correct such that the detection contacts will
open and close in accordance with the specifications prescribed in this standard.
Accordingly, the periodic certification of the point detector shall be done for mechanisms that
provide visual sighting of the detector actuator roller and also for mechanisms that do not
provide visual sighting of the detector actuator roller.
For mechanisms that provide visual sighting of the detector actuator roller, the following
requirements shall be complied with:
• The point detection settings shall be assured by checking the proximity of the detector
actuator roller relative to the detector slide notch. The relevant contacts shall open and
close in accordance with the go/no-go specifications prescribed in this standard. This may
be achieved without the need to slacken (float) the point lock.
• The point detector contacts shall be checked to be open while the point lock is tested at the
'no go' specification.
For mechanisms that do not provide visual sighting of the detector actuator roller, the following
requirements shall be complied with:
• The point lock shall be accordingly slackened (floated) to allow the lock to enter. This
provides the opportunity to check the point detection settings.
• The point detector contacts shall be checked to be in accordance with the go/no-go
specifications prescribed in this standard.
• The point lock shall then be readjusted and certified in accordance with the go/no-go
specifications prescribed in this standard.
Other methodologies that assure the correct detection of point switches in these circumstances
may be applied; however, the methodologies used shall be in accordance with signalling
principles, ASA.
24.5.2. Requirements for testing point operating bar detection on Claw Lock and Spherolock points
Point operating bar detection (also known as point lock coverage detection) on Claw Lock and
Spherolock points is tested to ensure adequate point lock coverage is achieved at the moment
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
The detector contacts shall not make until the point lock bolt has dropped into the locked
position.
24.5.4. Requirements for detection testing swing nose crossings The point detection settings of swing nose crossings are the same as that of other points.
24.5.5. Requirements for detection testing derailers The detector shall prove the position of the derailer, for example, derail position and clear
position.
Derailer detector contacts shall be made to close when the derailer is in a position to effectively
derail a train. The same contacts shall be made to open when the derailer is not in an effective
derail position.
Where contacts are used to also prove the derailer in a clear and safe position for the passage
of a train, the contacts shall only make when the derailer is in the fully cleared position.
Similarly, the same contacts shall be open when the derailer is not in the fully cleared position.
The detector contact settings can be adjusted slightly coarse because of the latitude between
the effective derail position and the fully cleared position.
24.5.6. Requirements for detection testing point back-drives The detector contacts of back-drive detectors (where fitted) shall be opened at approximately
6.4 mm for the closed-switch opening. This is measured at the back-drive detector. The detector
contacts shall be closed with a switch opening of 4.8 mm or less.
24.6. Provision for lock slide removal and wide cut notch point lock The provision to remove lock slides from point machines applies only to the points that are
trailing-only in both directions and operated by combined electric switch machines.
The provision to allow a wide cut notch in a point lock applies only to the following
configurations:
• open-switch catch points operated by combined electric switch machines
• open-switch catch points operated by signal branch electro-pneumatic or mechanical
mechanisms
• trailing-only position of points operated by signal branch electro-pneumatic or mechanical
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
24.6.1. Providing approval for lock slide removal and wide cut notch point lock Where the reliability of trailing-only points can be improved by the removal of point lock slides or
by the provision of a wide cut notch point lock, then it is permissible to implement such
arrangement in accordance with signalling design principles.
The responsible signal engineer shall approve these provisions and control a register of all
points with point lock-slides removed or with a wide cut notch point lock.
Note: Points fitted with wide cut notch point lock slides shall be inspected every two
years by a signal engineer as part of their mechanical interlocking inspection to ensure
the integrity of the arrangement is maintained and that the inscriptions remain in
accordance with the signalling plan or working sketch.
24.6.2. Requirements for lock slide removal and wide cut notch point lock Signalling safeworking procedures shall include the following requirements for the removal of
point lock slides in points operated by combined electric switch machines:
• the unused guide-ways on both sides of the machine are plugged to prevent entry of dust
and grit
• the points shall be identified as 'non-locked points' to network operators, for the purpose of
yard working
Signalling safeworking procedures shall include the following requirements for the provision of a
wide cut notch point lock for the open-switch catch point of points operated by combined electric
switch machines:
• the wide cut notch point lock shall be machined at an engineering machine shop
• the allowable cut out for the wide cut notch in the point lock shall not exceed 13 mm wider
than the respective locking dog
• the point lock slide shall be stamped with the words 'wide cut notch' together with the
applicable point end number, all in 6 mm letters
• the stamped text shall be adjacent to the wide cut notch on one side of the lock slide, and
on the top and bottom face at the end between the elongated slot and second hole
• an additional set of lines shall be inscribed on the opposite face corresponding to the new
wide cut notch point lock, and the old marks shall be stamped with a cross
• installation of wide cut notch point lock-slides shall be certified by a signal engineer
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
25.1. Objective of track circuit inspection, testing and maintenance The objective of track circuit inspection, testing and maintenance is to find and remove any
potential failure condition, and ensure as far as practicable that the track circuit will function
safely and reliably. The track circuit shall comprise all the necessary components required to
enable its safe and reliable operation.
The following are examples of track circuit components:
• track circuit power supplies
• transmitter/feed units
• receiver/processer units
• trackside units and interfaces
• track circuit resistor and capacitor units
• track circuit relays
• rail surface, track and ballast condition
• impedance bonds
• insulated rail joints
• equipment wiring, track wiring and cabling
• traction bonds and parallel bonds
• wiring connections, including rail connections
• lightning protection
The following are examples of specific tasks that pertain to track circuits:
• performing inspection and maintenance of track circuit components
• recording of power supply and track circuit voltages, currents and settings
• performing shunt tests, including train shunt test where applicable
• performing polarity tests, where applicable
• performing zero feed tests
Track circuits that fail safety testing criteria shall be immediately reported to the responsible
signal engineer or other relevant signal engineer. In the absence of prompt, effective remedial
action, the protecting signals shall be booked out of use. Track circuits shall not be left operating
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
25.4.6. CSEE and HVI Jeumont Schneider receiver rack position The task of plugging CSEE and HVI Jeumont Schneider track circuit receivers into their correct
rack positions is critical. The misalignment of a receiver by one module space can have unsafe
consequences, resulting in the permanent energisation of the track circuit relay.
These units shall be checked to be in their correct position whenever they are plugged into their
base. Additionally a check shall be made to ensure every vacant module position above and
below these units is fitted with obturation fittings and coding plugs.
25.4.7. Microtrax coded track circuits The Microtrax card file shall be securely mounted with all plug-in modules fully inserted and the
front panel holding down screws securely tightened.
Vacant positions on the cardfile shall have cover plates fitted at all times.
The boards, modules or vital power failure relay shall not be removed or replaced with the
Microtrax unit powered up.
Wiring from the Microtrax unit to the track interface panel should not be short-circuited or open-
circuited while the Microtrax unit is in operation. The Microtrax unit shall be turned off at both
ends before interfering with this wiring. Failure in doing so will place the Microtrax unit in
selective shut down mode.
When performing shunt tests, the slave end unit condition shall be monitored. The slave end
unit shall indicate its de-energised state by displaying '0000' in the 'TRK MARGIN' display. To
ensure the occupancy indication displayed remains constant, the track shunt shall be applied for
at least 30 seconds.
Microtrax operator keys for crossing loops may be issued to licensed signalling personnel for
the purpose of engineering work only and not for operational use. Where the keys are issued to
licensed signalling personnel, the keys shall be numbered and issued to the person who shall
be accountable for the security of the key. The key shall not be lent to other persons unless the
transfer is approved and documented by the responsible signal engineer.
Microtrax diagnostic and configuration software shall not be copied onto third party machines or
supplied to unauthorised persons. Under no circumstance shall the vital erasable programmable
read-only memory (EPROM) be duplicated or altered by field personnel.
The configuration of modules including associated EPROM shall be permitted only by the
contracted AEO providing the design assurance accountability.
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
The storage of Microtrax configuration data, for example, EPROM and version information shall
be registered and kept secure. This shall be managed by the contracted AEO who holds
accountability for the maintenance of signalling design records and data.
Note: A zero feed test is not required for Microtrax coded track circuits.
25.4.8. Audio frequency overlay track circuits (PSO 4000) The Safetran PSO 4000 audio frequency overlay track circuit receiver indicates its de-energised
state by the 'Rx-Int' led in the receiver occupancy display being extinguished. This shall be
monitored in conjunction with the signal display level on the receiver which indicates its
de-energised state by displaying a number less than '100'.
The track circuit relay shall also be observed to be in a de-energised state during this time.
25.5. Safety critical and safety significant track circuit tasks The safety critical and safety significant tasks for track circuits are mandatory and shall be
treated in accordance with Section 20.2 of this standard.
25.5.1. Safety critical tasks for double rail 50 Hz ac track circuits Double rail 50 Hz ac track circuits in electrified areas shall be periodically tested and certified for
unbalanced rail currents and voltage drop across connections to ensure their safe operation.
The frequency of this certification shall not exceed 30 days.
The values of these tests shall be documented on a track circuit record specific for this purpose.
The following tasks shall be included in signalling safeworking procedures for the testing and
certification of double rail 50 Hz ac track circuits:
• test track circuit relay coil voltage when unoccupied
• test current in each rail for balance at relay end
• test current in each rail for balance at feed end
• test current in each cable of impedance bond side lead for balance at up rail
• test current in each cable of impedance bond side lead for balance at down rail
25.5.2. Safety significant tasks for track circuits installed with parallel bonds Parallel bonds shall be periodically inspected for continuity and integrity. The frequency of this
inspection shall not exceed three months, except where parallel bonds are surface run, have
hypalon insulation and have welded rail connections. In this case, the inspection frequency can
be extended to 6 month intervals. In any case, signalling personnel shall take every opportunity
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
26. Inspection and testing of level crossing protection Level crossings are interfaces where rail corridors and road/pathways intersect. This interface
poses a risk which may result in a collision between users of level crossings and trains. This risk
increases as rail and road vehicle speeds and volumes increase over time.
Level crossing protection takes the form of either active or passive types as referenced in this
standard. Users at level crossings refer to road vehicles, pedestrians or cyclists, as applicable.
In some cases, dedicated pathways for pedestrians or cyclists are provided at level crossings.
Active level crossing protection includes type F flashing lights, bells and signage (for track and
road), and may include road boom barriers, pedestrian boom barriers or swing gates, pedestrian
lights, and pedestrian tone generators (sirens). Level crossing protection activation can be
controlled locally or remotely, or enabled automatically.
Passive level crossing protection is generally provided for roads that are less utilised or for
private roads and usually consists of stop or give-way and warning signage only.
At some level crossings, the activation equipment is interfaced with adjacent road traffic signals
to enable efficient management of road traffic. This aims to reduce the likelihood of road vehicle
queuing across the rail corridor or the road intersection.
The requirements for road signage provided for level crossing approach warning is not covered
by this standard.
26.1. Maintenance and inspection of level crossing protection equipment Signalling safeworking procedures shall prescribe the precautions and procedures necessary to
perform inspection, maintenance and emergency response while ensuring the safety
requirements of level crossing protection is afforded at all times. Additionally, signalling
personnel shall be vigilant when in the vicinity of level crossings, to observe for faults, damage
or vandalism that may affect its safe operation.
The moving parts of level crossing boom barriers and swing gates, including pedestrian
emergency access gates where provided, shall be kept clean, lubricated and checked for
efficient operation.
The operational time taken for the booms and gates to descend and ascend shall be checked to
be in accordance with the design requirements. Where these times are excessive, the
responsible signal engineer shall be notified and the matter investigated.
The balancing of boom barriers and swing gates shall also be checked and adjusted as
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
supply indicator (PSI) lights where available shall be observed to be turned ON at the
conclusion of the test.
This daily test shall be performed by licensed signalling personnel or qualified rail workers in
accordance with the network rules and procedures.
In addition to periodic maintenance, licensed signalling personnel shall perform a level crossing
operation test whenever they investigate reports of defective level crossing protection
equipment which includes associated power supply.
26.1.3. Reinstatement actions following maintenance or failure response Fault or warning conditions, detected by a level crossing monitor, shall be cleared before
leaving the level crossing site.
Whenever level crossing lamps are replaced or re-adjusted, the level crossing shall be operated
for sufficient time to confirm that the level crossing monitor’s lamp detection system (where
fitted) is working correctly.
At the conclusion of maintenance, testing or investigation, it shall be ensured that the level
crossing is fully operational and that nothing has been left switched off, disconnected or
unlocked including battery chargers, power supplies, test switches, emergency switches and
manual operating or overriding switches.
26.2. Treating reports of level crossing failure All reports of level crossing protection failure shall be duly investigated by licensed signalling
personnel. This includes any report of power supply defect associated with the level crossing, or
any fault or warning indication provided by a level crossing monitor.
Reports of signalling irregularity pertaining to level crossing protection shall be promptly
investigated by a signal engineer. The response to level crossing irregularities shall be in
accordance with Section 11 of this standard.
27. Inspection and testing of signalling interlockings New or altered signalling interlockings are tested when commissioned to ensure they comply
with their design requirement. Subsequently, the signalling commissioning engineer is required
to provide a copy of the associated design documentation to the responsible signal engineer to
indicate the altered locking details as commissioned. These design documents may include
locking tables, control tables, locking diagrams, signalling plans and working sketches.
The responsible signal engineer shall be accountable for retaining the most up-to-date versions
of signalling documentation relevant for the purpose of interlocking testing.
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
Periodic testing of mechanical and relay interlockings shall then be performed to ensure they
remain effective and in accordance with their design requirement. The responsible signal
engineer shall be accountable for ensuring these interlockings are periodically tested.
Signalling interlockings may also require testing in the following situations:
• when investigating a signalling irregularity or incident
• where there is doubt with the integrity of the interlocking
• whenever mechanical locking or associated covers are interfered with
The inspection and testing of signalling interlockings shall be done in accordance with
SPG 0711.
27.1. Authority to test signalling interlockings Interlocking testing, including signalling principles testing, shall only be performed by signalling
personnel who hold the competency for such testing.
Signalling personnel, holding a specific competency for interlocking tests (equivalent to an
interlocking certificate), are permitted to test mechanical interlocking items and mechanical
frames. These mechanical frames may include frames greater than eight levers. They are also
permitted to test relay interlockings and computer based interlockings.
Signal design engineers required to perform design integrity testing (principles testing) following
related new or altered work, shall also meet these competency requirements for testing
interlockings.
Signal engineers, who do not have the specific competency for interlocking tests, may perform
interlocking tests on mechanical interlocking items and mechanical frames of up to eight levers.
However, as part of an investigation which is in response to a signalling irregularity or incident,
or where there is doubt with the integrity of an operating interlocking, signal engineers are
further permitted to perform such interlocking tests on all types of interlockings.
Licensed interlocking fitters are permitted to test annett locks, duplex locks and other similar
mechanical items following maintenance of these items.
27.2. Testing altered locking on interlocking frames greater than eight levers Where a mechanical interlocking frame greater than eight levers is tested to certify an altered
locking arrangement, two testers shall be required to jointly conduct the test. Both testers shall
meet the same competency requirements for testing interlockings as stated in Section 27.1 of
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
Relay interlockings that fully comprise the following elements may be exempt from periodic
interlocking testing:
• plug-in type vital signalling relays
• PVC insulated and sheathed wires and cables
• double switched external interlocking circuits
• power supplies for vital interlocking circuits fitted with reliable earth leakage detection
Note: Mechanical items that form part of the relay interlocking are tested in
accordance with Section 27.4 of this standard.
27.6. Periodic testing of computer based interlockings Computer based interlockings may be exempt from periodic interlocking testing. The safety
integrity level required of these interlockings provides the necessary safety assurance
requirements for the signalling system.
However, validation and testing may still be required when commissioning new or altered works,
or otherwise in response to a signalling irregularity or incident.
Following are some computer based interlocking systems used in TfNSW:
• Solid State Interlocking (SSI)
• Microlok II
• Westlock
• Westrace
• Smartlock
Note: Mechanical items that form part of the computer based interlocking are tested in
accordance with Section 27.4 of this standard.
28. Inspection and testing of electrical insulation The integrity of electrical insulation used on vital signalling circuits forms an important aspect of
the safety assurance requirements for the signalling system. Electrical conductors used for
internal wiring, external cables and single-wires, power supplies and equipment are exposed to
many elements and forces that subject them to deterioration and damage. This may lead to vital
signalling functions being incorrectly activated by electrical leakage currents, which may result
in a signalling irregularity.
Therefore, the periodic testing of insulation properties of these conductors is important to ensure
they are adequately insulated from one another and from earth.
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
28.6. Inspection and testing of electrical conductor insulation The treatment of operational signalling when performing periodic insulation testing shall be done
in accordance with the maintenance requirements stated in Section 20.1 of this standard.
Wires or cable cores shall not be removed from their terminals for the purpose of insulation
testing unless necessary. Where it is necessary, only one wire shall be removed at a time and
the reconnection shall be suitably tested. The use of disconnection links or the unplugging of
coded type plug couplers shall be the preferred means to conduct this test.
Electronic equipment shall be disconnected before insulation testing to avoid damage caused
by the testing equipment.
The following are examples of such equipment that may be affected:
• power supplies
• electronic track circuit equipment
• timers and timer relays
• flashing relays
• solid state modules
• computer based interlocking equipment
• control system equipment
• telemetry equipment
28.6.1. Requirements for insulation testing of internal wiring Internal wiring referred in this standard is the wiring of vital signalling that is contained within
signal boxes, relay rooms and trackside signalling housings. It excludes trackside cable junction
boxes and the like, which only include through-connection terminals and not any internal wiring
for vital signalling equipment.
The internal wiring of circuits shall be preferably tested complete with all associated relay
contacts closed. Where this is not practical, the internal circuit shall be tested thoroughly by
testing all the individual parts of the circuit arranged when the relay contacts can be closed.
The circuits shall be first disconnected from their respective power supply (at all ends) before
commencing testing.
All internal wires used for vital signalling shall be tested to earth and to its associated metal
frame. The frequency of this test shall be in accordance with Table 5.
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
Where metal frames are earthed, the earth point used for insulation testing shall be the earth
that is connected to the frame.
Where reliable earth leakage detectors monitor the associated power supply busbar of internal
wiring, the requirement for periodic insulation inspection and testing of internal wiring may be
exempt.
28.6.2. Requirements for insulation testing of external main cables and single-wires External cables and single-wires referred in this standard are the conductors that provide the
external electrical connection for vital signalling that lie between signal boxes, relay rooms,
trackside housings and trackside equipment.
Signalling safeworking procedures shall categorise external cables and single-wires as follows:
• external main cables and single-wires – which connect signalling equipment housings to
one another
• external tail cables and single-wires – which connect signalling equipment housings to
trackside signalling equipment
• external power cables and single-wires – which supply electrical power to vital signalling
equipment
The frequency of these tests shall be in accordance with Table 5.
Periodic inspection and testing of external cables and single-wires shall include observation and
assessment of wiring terminations at trackside junction boxes and equipment. The condition of
conductor insulation shall also be observed, where the conductors are visible, for damage or
degradation. For example, evidence of verdigris or other corrosion.
Additionally, cable routes shall be observed for any likely damage or degradation. For example,
where earth works have taken place in the vicinity of buried cable routes or where trackwork has
taken place near cable troughing and pits.
External cables and single-wires shall be isolated from the live (working) portion. Computer
based interlocking equipment and other similar electronic equipment shall be turned off before
testing associated wiring. Lightning arrestors and surge protection apparatus associated with
external cables and single-wires shall be isolated during testing.
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
External cables and single-wires category
Insulation type
Reliable ELD fitted
Double switched circuit
Minimum conductors nominated for testing
Additional testing requirements
External power cables and single-wires
PVC Yes Not applicable
Nil Nil
No Not applicable
All Nil
Non-PVC Yes Not applicable
Nil Nil
No Not applicable
All Nil
The following information provides the criteria for nominating conductors for testing:
• A spare conductor may be deemed as counting towards the minimum amount of
conductors nominated for testing.
• Where there are fewer spares than the minimum amount of conductors nominated for
testing, working conductors from the outer layer of a cable shall be chosen for the testing.
Where the outer layer is directly connected to monitored busbars the next layer shall be
chosen for testing.
• External power cables and single-wires are exempt from the 'minimum amount of
conductors' requirement where the associated power supply busbar is monitored by a
reliable earth leakage detector. This should generally limit the scope of testing for external
power cables to the cable sheaths only.
28.7. Circuits exempt from periodic insulation inspection and testing Conductors that are used in circuits exclusively in the circumstances stated in Section 28.7.1
through to Section 28.7.4 of this standard may be exempt from periodic insulation inspection
and testing.
However, while conductors that are exempt from periodic insulation testing do not pose a risk to
signalling integrity, they may still pose a risk to reliability, personnel safety or cause a fire, in the
event of insulation breakdown.
For these reasons, the requirement to periodically inspect these conductors to assess their
insulation condition shall be considered by the contracted AEO.
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
28.7.1. Exemptions for Solid State Interlocking (SSI) and Westlock systems Following are the specific circuits and items of Solid State Interlocking and Westlock systems
that may be exempt from periodic insulation inspection and testing:
• central interlocking cubicle wiring and equipment
• technician's terminal wiring and equipment
• long distance terminal and data link module wiring and equipment
• data link wiring and cables
• isolation transformers and secondary wiring
• trackside functional modules and associated input/output wiring, including external
conductors where directly connected to inputs/outputs of trackside functional modules
Note: Circuits not directly connected to trackside functional modules, such as circuits
emanating from relay operated circuits, are not exempt from periodic insulation
testing.
28.7.2. Exemptions for Microlok II systems Following are the specific circuits and items of Microlok II systems that may be exempt from
periodic insulation inspection and testing:
• Microlok II cardfile and cards
• conductors of output circuits between Microlok II equipment and steering diodes or
controlled equipment where steering diodes are not fitted
• communication link wiring and equipment
• conductors of vital relay output circuits where isolation modules are fitted
• conductors of 50 V input circuits where the associated power supply busbar is monitored
by a reliable earth leakage detector
• conductors of vital relay output circuits between the duplication diodes and relays of
duplicated systems where the associated power supply busbar is monitored by a reliable
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
28.7.3. Exemptions for Westrace systems Following are the specific circuits and items of Westrace systems that may be exempt from
periodic insulation inspection and testing:
• Westrace cardfile and cards
• conductors of circuits from vital lamp output modules to signal lights where either of the
following conditions are met:
o the associated power supply busbar is monitored by a reliable earth leakage detector
o an isolation transformer is fitted
• conductors of circuits from vital relay output modules
• conductors of vital inputs where either the associated power supply busbar is monitored by
a reliable earth leakage detector
• communication link wiring and equipment
28.7.4. Exemptions for telephones circuits, non-vital circuits and track circuits Following are the additional specific circuits that may be exempt from periodic insulation
inspection and testing:
• signalling communication (telephone) circuits
• non-vital signalling wiring and equipment where the non-vital signalling circuits are
physically separated from vital signalling circuits, or otherwise where the associated power
supply busbar is monitored by a reliable earth leakage detector
• track circuit cables and single-wires which meet the following conditions:
o there is no combination of feed-end and relay-end of like track circuits that are run in
the same routing
o there is no more than one relay-end of like track circuits that are run in the same
routing
Note: Where the track circuit exemption condition is not met, and the track circuit
cable has a conductive sheath, screen or drain wire, then the insulation testing
requirement can be achieved by testing only the sheath, screen or drain wire, as
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
29. Specific requirements for computer based interlockings Computer based interlockings referred in this standard apply to the following systems:
• Solid State Interlocking (SSI) systems
• Microlok II systems
• Westrace systems
• emerging computer based signalling systems
The specific requirements and precautions prescribed for computer based interlockings shall
supplement the general requirements prescribed in this standard as they pertain. They shall be
read and applied in conjunction with each other as necessary. For example, when securing
signalling apparatus out of use that is interlocked by a Solid State Interlocking, both the specific
Solid State Interlocking requirements and the general requirements stated in Section 13 of this
standard shall apply.
Signalling safeworking procedures shall prescribe the specific procedures and precautions
associated with each computer based signalling system that is in operation within their network.
29.1. Requirements for Solid State Interlocking systems The specific requirements that pertain to Solid State Interlocking systems are stated in Section
29.1.1 through Section 29.1.7.
Solid State Interlocking equipment includes the following items:
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
29.1.1. Security of Solid State Interlocking components and configuration data Solid State Interlocking module seals shall not be broken by field personnel. Only persons
authorised and competent for the specific work shall be permitted to interfere with the internal
components of these modules. Generally, this task is conducted by the equipment manufacturer
or other authorised agent. Defective modules shall be tagged with the date, defect details and
location.
Any such equipment found in the field with a broken seal or no seal shall be reported to the
responsible signal engineer for attention.
The configuration of memory modules including associated EPROM and subsequent sealing
shall be permitted only by the contracted AEO providing the design assurance accountability.
The storage of Solid State Interlocking configuration data (such as memory modules) and
associated spare items (such as EPROMs) shall be registered and kept secure. The contracted
AEO who holds accountability for the maintenance of signalling design records and data shall
manage the storage of Solid State Interlocking configuration data.
29.1.2. Handling and storage of Solid State Interlocking equipment Solid State Interlocking equipment contains electronic components that may be damaged by
misuse. Modules shall be handled, transported and stored with care and not subjected to
damage or deterioration.
The modules shall be stored on racks in enclosed housings in a clean, dry and non-corrosive
environment below 60 °C.
29.1.3. Interfering with operational Solid State Interlocking equipment
When it is necessary to remove multi processor modules, diagnostic modules or panel
processor modules from the central interlocking for replacement purposes, they shall be
removed in conjunction with their associated memory module. The replacement modules shall
be pre-fitted with the correct memory module.
Modules shall not be disconnected unless first powered down. The powering down of a
trackside functional module shall first necessitate the removal of the '110v NX' disconnect pin.
A module's compatibility and correct configuration shall be assured before replacing any module
in operation with another module.
When the central interlocking has been stopped, switched off and restarted, any technician’s
control that was previously applied may be lost (removed). Therefore the technician's control log
book shall be checked to determine if any controls are missing as a result of the central
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
interlocking's 'off state'. Any controls noted missing, shall be reinstated upon re-starting the
central interlocking.
Module retaining screws and plug couplers shall be secured before restoring the power.
Note: Points will not show a detection status to the signaller when a points module is
replaced or powered off and on. Subsequently, upon restoring power to a points
module, the signaller is required to key the points to the last known position so that
detection can be restored.
29.1.4. Maintainer's interface to Solid State Interlocking The maintainer's interface to the central interlocking is provided by the technician’s terminal and
associated peripheral equipment. This equipment provides access to review interlocking data
and events, and enables specific control functions of the central interlocking.
The facility generally comprises the following equipment:
• technician's terminal, keyboard, monitor and tracker ball
• fault and event printer
• logger pc, monitor, keyboard and mouse
• remote access hardware and telephone line
The facility is connected to the system's diagnostic module which processes the fault and
diagnostic information.
The technician's terminal may be accessed locally or remotely. The responsible signal engineer
shall manage the access requirements as necessary, including administering the access
passwords.
Information from the technician's terminal and associated equipment can be used as evidence
when investigating serious incidents and signalling irregularities. Therefore any failure of such
equipment shall be promptly actioned and rectified.
The technician's terminal enables specific interlocking controls that can be applied or removed
to the central interlocking by a maintainer.
The following is a list of controls enabled by the technician's terminal:
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
29.2. Requirements for Microlok II systems The specific requirements that pertain to Microlok II systems are stated in Section 29.2.1
through Section 29.2.8.
Microlok II equipment includes the following items:
• Microlok II cardfile and boards
• CPU board
• vital input and output board
• non-vital input/output board
• lamp driver board
• vital control output relay
• object controller module
• power supply board
29.2.1. Security of Microlok II system configuration data The configuration of application data of Microlok II systems shall be permitted only by the
contracted AEO providing the design assurance accountability.
Under no circumstances shall any Microlok II maintenance and configuration software be copied
onto third party machines or supplied to unauthorised persons.
The storage of Microlok II system configuration data (such as executive, application and
network configuration files) and associated spare items (such as compiled central processor unit
(CPU) boards) shall be registered and kept secure. The contracted AEO who holds
accountability for the maintenance of signalling design records and data shall mange the
storage of Microlok II system configuration data.
29.2.2. Handling and storage of Microlok II system equipment Microlok II equipment contains electronic components that may be damaged by misuse. Boards
and modules shall be handled, transported and stored with care and not subjected to damage
or deterioration.
The boards and modules shall be stored on racks in enclosed housings in a clean, dry and non-
corrosive environment below 60 °C.
Anti-static protection handling procedures shall be applied when handling Microlok II boards and
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
29.2.3. Microlok II system time setting Microlok II system clocks shall be set to Australian Eastern Standard time only. The clock times
shall not be adjusted to align with daylight saving time.
Where the Microlok II architecture provides for multiple cardfiles, all the cardfile times shall be
set using the same time reference. For example, the same laptop clock shall be used to set all
the Microlok II cardfiles.
29.2.4. Authority to configure and upload Microlok II files When replacing a CPU module or object controller in operation, licensed signalling personnel
are permitted to perform the following tasks:
• upload executive software file, in accordance with the installed data form
• upload application data file, in accordance with the installed data form
• check and set adjustable items, in accordance with the site specific maintenance
procedure
• upload object controller network configuration files for the 'COM1', 'COM2' and 'Web Tool
Ethernet' ports, in accordance with the installed data form
• program new EPROM serial dongle to replace a damaged or lost EPROM serial dongle, in
accordance with the installed data form
Note: Incorrect uploading of network configuration files for the 'Web Tool Ethernet' can
fail the object controller. Confirm the correct file and process before performing this
action.
The following tasks may be performed only by a signal engineer competent to do such work on
behalf of the contracted AEO providing the design assurance accountability:
• alter adjustable configuration items to a value other than that detailed in the site specific
maintenance manual
• upload executive software file with a file other than that detailed on the installed data form
• upload application data file with a file other than that detailed on the installed data form
• upload object controller network configuration file with a file other than that detailed on the
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
• project site integrity meetings and practical completion inspections
• signalling irregularity and failure follow-up investigations
30.3. Surveillance inspection reports and action requirements The results of surveillance inspections shall be recorded in a specific report. The report
outcomes shall contain an itemised asset list of the inspection area, details of inspectors and
the details of any personnel observed or stakeholders engaged. The report shall also include
action requirements for the rectification of defects. These actions shall be priority based and
time scaled. A defect management system shall be used to manage this requirement.
The report shall also contain recommendations as applicable to the inspection. The
recommendations may include increased supervision or local instructions to correct
deficiencies, asset renewal programs, training plan requirements and improvements to
procedures, standards and so on.
Signal engineers shall also record occasions where they have directly observed personnel
performing signalling related tasks, particularly safety critical and safety significant tasks.
The responsible signal engineer shall be accountable to ensure surveillance inspection reports
are duly produced and actioned accordingly.
31. Housekeeping and protection of signalling assets Signalling trackside apparatus and equipment housings shall be kept clean and tidy, and left in
a secured state when not being worked-on.
Equipment housings shall include relay rooms, walk-in enclosures, location cupboards, and
lower floors of signal boxes. These shall be kept locked whenever possible to prevent
unauthorised access and vandalism. Spares and materials shall not be stored in these places,
unless they are appropriately placed on racks or cupboards provided specially for the purpose.
Highly inflammable material shall not be stored in these places. Locking arrangements shall be
maintained in good condition.
Before securing signalling apparatus or housings, signalling personnel shall check that
everything is in order and properly connected and that nothing has been left loose, foul of
standard clearances, or in a potentially unsafe condition.
Access pathways, ladders and other such items shall be maintained in good order, so as to
provide adequate access to signalling apparatus and housings. Excess vegetation, rubbish or
surplus materials shall be removed during maintenance visits.
Lighting of relay rooms and cupboards shall be maintained in good order to ensure adequate
T HR SC 02000 ST Mandatory Requirements for Signalling Safeworking Procedures
Version 1.0 Effective Date: 01 April 2015
• keys clearly labelled, giving full particulars
• detailed records of keys in storage or transit, kept up to date in regards to movements,
controlled by the responsible signal engineer
34.2. Dispatching operational safeworking keys for repair, replacement or cancellation A specific record shall be used when despatching operational safeworking keys for repair,
replacement or cancellation, for the purpose of transmittal and tracking. The following details
shall be included on the record:
• reason for the dispatch
• key details
• name of all dispatchers
• name of all recipients
• date of transactions
The record shall be progressively compiled by the relevant stakeholders throughout the various
stages of dispatching and receiving. Abbreviations shall not be used to describe station names
or other details. The record shall be controlled by the responsible signal engineer.
Operational safeworking keys shall be dispatched in a suitable box locked with an SWI padlock
(or similar) accompanied by the record.
The responsible signal engineer shall account for the content of keys when dispatched and
received. When operational safeworking keys are returned, the responsible signal engineer
shall inspect the key inscription and number, and if correct, permit the distribution of the keys for
operational use.
The end receiver shall forward the completed record back to the responsible signal engineer for