19-02-2018, 10:20 AM
Only had the opportunity for a quick review. Hopefully others will weigh in too.
The terms hazard and risk are frequently misused on exam papers.
a) suggest there are more hazards; damage during weed clearance, vermin/animals... wouldn't recommend raised troughing (for anything except as last resort and almost certainly never for a single tail cable) but you could armour it or cleat it to the ballast, make it shorter during the design process!
b) plastic pipe is no longer permitted on NR; hollow sleepers or cleat to sleeper. Other causes of damage are pway works, crushing...
c) fauna is plant life, vermin includes rats. Troughing is normal for these cables. Buried troughing can reduce the likelihood of theft.
d) think it is asking about armouring when passing through walls/conduits plus EMI/EMC immunity and possible cable segregation from power/data cables.
Note; the question asked about mechanical and electrical.
Pt2 5) no especially for large cables due to weight and human factors issues for maintenance/installation.
Pt2 7) FO can and is used in signalling applications too. Less likely to be stolen, cheaper but requires specialist skills to resplice.
Overall: method for answering Pt2 is good, Pt1 didn't fully answer the question - hazard[s] < plural. With a bit of work and some practice (aim 25 minutes to answer a question, i.e. one minute per mark) you'll be on the right track for a decent result.
Well done.
The terms hazard and risk are frequently misused on exam papers.
a) suggest there are more hazards; damage during weed clearance, vermin/animals... wouldn't recommend raised troughing (for anything except as last resort and almost certainly never for a single tail cable) but you could armour it or cleat it to the ballast, make it shorter during the design process!
b) plastic pipe is no longer permitted on NR; hollow sleepers or cleat to sleeper. Other causes of damage are pway works, crushing...
c) fauna is plant life, vermin includes rats. Troughing is normal for these cables. Buried troughing can reduce the likelihood of theft.
d) think it is asking about armouring when passing through walls/conduits plus EMI/EMC immunity and possible cable segregation from power/data cables.
Note; the question asked about mechanical and electrical.
Pt2 5) no especially for large cables due to weight and human factors issues for maintenance/installation.
Pt2 7) FO can and is used in signalling applications too. Less likely to be stolen, cheaper but requires specialist skills to resplice.
Overall: method for answering Pt2 is good, Pt1 didn't fully answer the question - hazard[s] < plural. With a bit of work and some practice (aim 25 minutes to answer a question, i.e. one minute per mark) you'll be on the right track for a decent result.
Well done.
Le coureur