I don't see the difference in your wording.....to me the word order does not affect the meaning.
I am sure that they want you to give a total of 9 hazards-
3 applicable for your example in (i),
3 for (ii) and
3 for (iii).
Further they want different hazards in each case and so if you want to get your full 9 marks for the section, then give them what they want which is at least one cause and one effect for every one of the 9.
Also note that whereas perhaps GPS can be used as one of the diverse means of determining speed and location of a train, do not simply equate train position reports in ETCS with GPS. The prime means is via reading track balise to get an absolute position fix and subsequently using odometry looking at wheel revolutions to estimate movement since passing the balise- generally doppler radar is used as a diverse input into the odometry and potentially GPS could be used for this.
So one might focus upon:
track circuits:
loss of train shunt due to rusty rails,
EMI from traction exceeding the immunity of detector / relay,
failed insulated block joint permitting voltage from one section to be applied to the receiver of the adjacent
axle counters:
following an axle counter section having become disturbed, the signaller in error resetting a different one that was actually occupied at the time,
a possession being surrendered with an engineering vehicle having being left on track by mistake,
axle counter head becomes detached from the rails
train position reports:
temporary loss of power supply at control centre resulting in uncertainty of how many trains are in the affected area and where precisely they are,
a failed balise having been replaced but having been incorrectly programmed for the position it was installed,
poor adhesion conditions leading to excessive wheel slip / slide
I am sure that they want you to give a total of 9 hazards-
3 applicable for your example in (i),
3 for (ii) and
3 for (iii).
Further they want different hazards in each case and so if you want to get your full 9 marks for the section, then give them what they want which is at least one cause and one effect for every one of the 9.
Also note that whereas perhaps GPS can be used as one of the diverse means of determining speed and location of a train, do not simply equate train position reports in ETCS with GPS. The prime means is via reading track balise to get an absolute position fix and subsequently using odometry looking at wheel revolutions to estimate movement since passing the balise- generally doppler radar is used as a diverse input into the odometry and potentially GPS could be used for this.
So one might focus upon:
track circuits:
loss of train shunt due to rusty rails,
EMI from traction exceeding the immunity of detector / relay,
failed insulated block joint permitting voltage from one section to be applied to the receiver of the adjacent
axle counters:
following an axle counter section having become disturbed, the signaller in error resetting a different one that was actually occupied at the time,
a possession being surrendered with an engineering vehicle having being left on track by mistake,
axle counter head becomes detached from the rails
train position reports:
temporary loss of power supply at control centre resulting in uncertainty of how many trains are in the affected area and where precisely they are,
a failed balise having been replaced but having been incorrectly programmed for the position it was installed,
poor adhesion conditions leading to excessive wheel slip / slide
(12-09-2014, 01:05 PM)neil-thomson Wrote: In which case i think the question could be worded more clearly. I took that as 'for each...describe three safety hazards' rather than 'describe three safety hazard for each'.
I may be reading into it too much...
PJW