PTS PTS - Personal Track Safety Safety Critical Communications 2 — Questions and Answers
Question 1: What is a 'three-part communication' and why is it used for safety-critical messages on the railway?
- A communication system using three radio channels simultaneously
- A protocol where the sender states the message, the receiver reads it back, and the sender confirms it is correct — ensuring the message is accurately received (Correct answer)
- A rule requiring all safety messages to be given three times
- A format for writing safety documentation with three sections
Correct answer: A protocol where the sender states the message, the receiver reads it back, and the sender confirms it is correct — ensuring the message is accurately received
Three-part communication (challenge, readback, confirmation) ensures that safety-critical messages are accurately received and understood, reducing errors that could cause accidents.
Three-part communication is the standard protocol for safety-critical verbal communications on the railway. The sender states the message clearly (e.g. 'Line blockage confirmed on Up Main between mileposts 23 and 24'). The receiver reads back the full message. The sender then confirms the readback is correct or corrects any errors. This three-part exchange ensures that both parties have the same understanding of the message. It is used for line blockage requests, protection confirmations, and emergency communications. The protocol is defined in the Network Rail Rule Book and is fundamental to safe operations.
Question 2: What should a COSS do if they are uncertain that a verbal message from the signaller has been fully understood?
- Assume the message is correct and proceed with work
- Request the signaller to repeat the message and use three-part communication to confirm accuracy (Correct answer)
- Write the message down and have the signaller sign the record
- Contact a colleague to relay the message a second time
Correct answer: Request the signaller to repeat the message and use three-part communication to confirm accuracy
If any doubt exists about a received message, the COSS must ask for it to be repeated and use three-part communication to verify accuracy before acting on it.
Safety-critical communications must be accurate — acting on a misunderstood message in a railway context can have fatal consequences. The COSS must never assume or guess the content of a message. If there is any uncertainty due to radio quality, noise, or complexity, the message must be requested again in full. Three-part communication should be used to verify the final message before acting. This may seem time-consuming but is far preferable to acting on incorrect information. The Rule Book explicitly requires three-part communication for specified safety-critical verbal exchanges.
Question 3: What is the purpose of using standard railway terminology in safety-critical communications?
- It is a formality to demonstrate professional competence
- Standard terminology ensures unambiguous communication by using precise, universally understood terms that reduce the risk of misinterpretation (Correct answer)
- It helps maintain the professional image of the railway industry
- Standard terms are required only in written communications, not verbal
Correct answer: Standard terminology ensures unambiguous communication by using precise, universally understood terms that reduce the risk of misinterpretation
Standard railway terminology provides precise, unambiguous language understood by all trained personnel, eliminating misinterpretations that could cause accidents.
Railway safety-critical communications use specific terminology defined in the Network Rail Rule Book to ensure every word has a precise, universally agreed meaning. For example, 'Up line' and 'Down line' have specific directional meanings; 'line clear' means something specific to the signaller. Using non-standard or colloquial language in safety-critical communications introduces ambiguity and increases the risk of misunderstanding. During PTS and COSS training, workers learn the correct terminology and must apply it consistently. Misuse of terminology in a communication to the signaller could result in an incorrect protection arrangement being put in place.
Question 4: When is radio communication preferred over mobile phone for safety-critical messages on Network Rail infrastructure?
- Mobile phones are always preferred as they are more reliable
- Network Rail Integrated Electronic Control Centre (IECC) radios or GSM-R are preferred as they provide direct, reliable communication with signallers in real time without network congestion issues (Correct answer)
- Radio is only used in tunnels where mobile signals are absent
- The choice between radio and mobile is left to the COSS's personal preference
Correct answer: Network Rail Integrated Electronic Control Centre (IECC) radios or GSM-R are preferred as they provide direct, reliable communication with signallers in real time without network congestion issues
GSM-R (Global System for Mobile Communications — Railway) or IECC radio provides dedicated, prioritised communication with signallers that is more reliable and secure than standard mobile networks for safety-critical use.
GSM-R is the dedicated digital radio communication system used by Network Rail for safety-critical communications between COSSes, Engineering Supervisors, and signallers. It operates on a dedicated, protected radio frequency spectrum with priority call features, providing reliable communication even in congested areas. Standard mobile phones using commercial networks are subject to congestion, signal loss, and dropped calls that are unacceptable for safety-critical communications. COSSes must have a working, charged GSM-R handset or authorised alternative before accessing the track. GSM-R is being replaced by FRMCS (Future Railway Mobile Communication System) in the coming years.
Question 5: What action must be taken if a COSS's radio fails during an active line blockage?
- Continue work using mobile phone as backup without informing the signaller
- Suspend all work within the safe working limits immediately, ensure workers are in a position of safety, and attempt to re-establish communication — work may not resume until communication with the signaller is restored (Correct answer)
- Carry on working and log the radio failure for maintenance to investigate later
- Ask the nearest train driver to relay messages to the signaller
Correct answer: Suspend all work within the safe working limits immediately, ensure workers are in a position of safety, and attempt to re-establish communication — work may not resume until communication with the signaller is restored
Radio failure during an active line blockage means the COSS cannot confirm the blockage status — all work must stop and workers must be withdrawn until communication is restored.
An active line blockage requires ongoing communication between the COSS and signaller. If the radio fails, the COSS loses the ability to confirm that the blockage is still in place (the signaller may need to cancel it for operational reasons), receive warnings about trains, or call for emergency assistance. All work must be suspended immediately and workers withdrawn to a position of safety. The COSS must attempt to restore communication using a backup method (a second radio, landline, or emergency telephone if available). Work must not resume until reliable communication with the signaller is established. This requirement is non-negotiable.
Question 6: What is the correct response of a COSS when the signaller says 'your line blockage is no longer in place'?
- Acknowledge and continue working for up to 5 minutes to complete the current task
- Immediately withdraw all workers to a position of safety and confirm they are clear before acknowledging to the signaller (Correct answer)
- Ask the signaller to reinstate the blockage before responding
- Cancel work only if a train is visible
Correct answer: Immediately withdraw all workers to a position of safety and confirm they are clear before acknowledging to the signaller
If the signaller cancels a line blockage, the COSS must immediately withdraw all workers to a position of safety before anything else — trains could be authorised into the section at any moment.
When a line blockage is cancelled by the signaller, trains may be authorised into the previously blocked section immediately. The COSS must immediately withdraw all workers from the track to a position of safety — this takes absolute priority over completing tasks or recovering tools. Once all workers are confirmed in a position of safety, the COSS confirms this to the signaller. Work cannot resume until a new protection arrangement is obtained and confirmed. This scenario can occur due to operational emergencies, errors, or changed train running — COSSes must always be prepared to act instantly on notification.
PTS PTS - Personal Track Safety Safety Critical Communications 2
What is a 'three-part communication' and why is it used for safety-critical messages on the railway?