2010 Q6 lineside phones

[dorothy.pipet]

An attempt for comments please
- not exam conditions or timed

[PJW]

An attempt for comments please
- not exam conditions or timed

Not too many comments on this one; sensible length for 30 mins.

Good presentation methodology- the numbering of the mitigations allowing easy cross-ref to another hazard to avoid repetition was good idea.

If I were to be critical, it would be that there was some overlap between the disadvantages in the first part and the hazards of the second and you wouldn't get the same marks twice.  However there was probably more in part 1 than necessary to gain the marks, so could afford some not to score- but of course it still cost you the time to write.  

I think that I may have made more of

• the on-going regular testing to give confidence that would work when needed and the costs which go with that, 
  
• the likelihood of needing to replace cabling mid-life, 
  
• the cost of provision and constraints associated with the associated driver's walkway.
  

Another point that could have been worth making was that if one lineside phone isn't working, there is a high probability that there would be another one not too far away that probably would work, yet the loss of a radio base station might mean a whole geographic area might lose its comms (although clearly this could be mitigated by diverse coverage).

The traditional lineside phone system is very separate from the traditional signalling system; there are very few common mode failures that would disrupt the communication in the event of a failure affecting the signalling system extensively and this is a very desirable quality in able to be operate some form of train service.  However for the last decade or more, schemes have tended to route CBI data over telecoms links so some of this inherent diversity has been lost.  

For ETCS L2, the same telecoms network is inevitably used to carry the information to the radio base station to transmit to the train as is used to carry the voice communication and hence there is a chance that the same fault could lead to the loss of the signalling and the means of degraded mode working.  It is obviously very important that the highest RAMS is achieved and to incorporate the highest practicable level of diversity within the overall system and to make the voice as separate as possible to the channels which carry the signalling data.  Another mitigation would be to provide some fixed lineside phones at the block markers surrounding an island of pointwork even if no phones are provided in the plain line sections between such islands.
Hence I think that I would have concentrated the first section with those advantages /disadvantages which are not directly hazardous, reserving those for the second part.  


I think that the second page covered the second part very well, on the assumption that this was all new material rather than repeating bits from page 1. 
Would probably have expanded 10/12 to put a little more detail re communication protocol (lead responsibility, repeating back and indeed the recipient of the call challenging the caller to ensure that they are indeed in a place of safety, not driving etc.)

Having said all that, this was a good answer.  
HOWEVER I think that the primary reason why it wouldn't warrant a Distinction is that the items listed as "hazards" often weren't strictly hazards but typically are a cause of an unstated hazard.  
You can perhaps best regard a hazard as "an accident waiting to happen"; it is a condition which (often combined with an unsafe action as a trigger) could result in an accident.  Although from what you wrote one can infer the hazard in each case, it isn't explicitly stated.

So item 1 would be a hazard in the circumstances that some emergency had arisen (e.g. a bridge strike by road vehicle, a tunnel collapse) and establishing communication quickly could have avoided or mitigated its effect.
Item 2, the true hazard would be the misunderstanding that could arise meaning that the driver thought they had been authorised to make a movement beyond where the signaller had intended.
Item 3 hazard would be the caller unintentionally moving foul of a running line on which traffic had not been stopped.
Item 4 associated hazard is really the same as item 2, but the cause is a bit different; in this instance the caller is themselves confused where they are and hence although the signaller correctly understand, the information conveyed is actually wrong.  It is possible that the signaller on the strength of this information believes that they are talking to one driver, when in fact they are talking to a different one.