13-09-2017, 09:01 PM
I've not really read your answer but you need to think as widely as possible so some disjointed thoughts for part A:
- Track equipment might be incorrectly installed - ATP/ETCS balises missing or mis-programmed
- some other fault on trackside such as loss of power (TPWS)
- on-train equipment may malfunction or be isolated/overide/wrong mode - this could be for a genuine reason such as calling past a signal
- or the breaking performance is out of spec - adhesion such as leaves/ice/oil on the line, poor maintenance and so on.
- operational stuff i.e. overspeed which TPWS does not catch on the approach,
- or signal replaced in front of a train,
- or driver error doesn't see /respond to caution aspects
- or driver cancels TPWS warning without braking
- poor design e.g. insufficient OSS loops or gradient not taken into account, or insufficient balises (odometry not reset frequently enough so within cumulative tolerances).
Then section B it depends how you define the system, but I think it implies where the equipment is working but the conditions/human are not, so
- adhesion, override,
- TPWS worst case is when the driver passes an OSS just under the trigger speed then accelerates.
- if the signal is replaced in front of the train for ETCS the route locking is held so the train will pass the hazard point but it will be safe to do so.
I would interpret that the 2nd part wants a little more detail on the specific items. I see no reason not to include the cases like ETCS where the SPADding train is protected
If you want to talk about overlaps then you need to explain how that "translates" to end of movement authority and hazardous location in the question - consider: the overlap on an Automatic signal does not mean there is a hazard after it.
- Track equipment might be incorrectly installed - ATP/ETCS balises missing or mis-programmed
- some other fault on trackside such as loss of power (TPWS)
- on-train equipment may malfunction or be isolated/overide/wrong mode - this could be for a genuine reason such as calling past a signal
- or the breaking performance is out of spec - adhesion such as leaves/ice/oil on the line, poor maintenance and so on.
- operational stuff i.e. overspeed which TPWS does not catch on the approach,
- or signal replaced in front of a train,
- or driver error doesn't see /respond to caution aspects
- or driver cancels TPWS warning without braking
- poor design e.g. insufficient OSS loops or gradient not taken into account, or insufficient balises (odometry not reset frequently enough so within cumulative tolerances).
Then section B it depends how you define the system, but I think it implies where the equipment is working but the conditions/human are not, so
- adhesion, override,
- TPWS worst case is when the driver passes an OSS just under the trigger speed then accelerates.
- if the signal is replaced in front of the train for ETCS the route locking is held so the train will pass the hazard point but it will be safe to do so.
I would interpret that the 2nd part wants a little more detail on the specific items. I see no reason not to include the cases like ETCS where the SPADding train is protected
If you want to talk about overlaps then you need to explain how that "translates" to end of movement authority and hazardous location in the question - consider: the overlap on an Automatic signal does not mean there is a hazard after it.