(30-03-2010, 10:48 PM)interesting_signal Wrote: Ok, here's what I have done so far. I'm still working on questions 8, 9 and 16.It is evident that you have read and understood the Study Pack and also avoided a few of the "traps". You also generally did a good job of explaining your answers. However some brief comments on those that I have looked at so far:
Q1. You made the unstated assumption that the headway time calculated was to be at the maximum permissible speed. Also you calculated the headway at MINIMUM signal spacing, not "maximum" as requested.
Q3 (and others). You used symbol "S" both for the braaking distance and the Sighting Distance; ok you didn't confuse yourself, but do beware of mixing and matching between different conventions and make sure any answer is self consistent!
Also Q3 shows a slight confusion I think- but whether of expression or understanding I do not know. Third sentence should read If the ratio had been less than 2, then 3 aspect signalling would not have been capable of delivering the required headway and therefore 4 aspect signalling would be a necessity. Last sentence should have stated .... as this gives the most economical means of achieving the required headway (MAXIMUM signal spacing, so minimum number of signals required for given distance)
Q4. You surely meant that the distant signal would be prior to (on the approach to) the stop signal; the nomenclature is NOT in advance but in rear
Q5. Err- all the figures seem to be the same as Q4 with a slightly different end wording; not an answer to Q5????
Q7. THINK. Does a train going down hill need a longer or shorter distance to stop than one on the level......? Lesson: firstly take a bit more care re the maths; secondly do a "common sense" check.
Q10. Only quibble is use of the word "speed" rather than "velocity"; it is a vector quantity and the "sign" is important [relevant to Q7 of course]
PJW