27-08-2011, 09:49 PM
I have been sent another person's version of the calculations for this year, to which I have added "sticky note" comments within the pdf file that show up on the scan and reveal themselves when you hover over them.
Pretty similar attempt to another one recently and hence my comments are very similar:
It is very clearly set out and goes through logically.
It is "going through a process" and therefore not necessarily directly answering the actual question which was set.
It quotes the headway formula without a diagram to explain derivation.
It uses what is termed an "aspect ratio" which is not explained or justified.
It calculates the minimum headway for 3 aspect signals which was not required in the 2004 paper.
It does however also determine the acceptable range of spacing that does answer the question related to signalling the layout.
It attempts to use the same short cut method for stopping headway, doesn't completely explain what trying to do, but it was a bit better because the "penny did actually drop" with me this time. However it is based upon the 3 aspects being placed at minimum spacing rather than any greater figure that matches what was declared would be used.
Assumption were placed at the end as an after thought, although they had previously been utilised. No comment was made regarding the necessity or not of designing any contingency into the signalling relating
to the declared headway requirement and level of utilisation.
Pretty similar attempt to another one recently and hence my comments are very similar:
It is very clearly set out and goes through logically.
It is "going through a process" and therefore not necessarily directly answering the actual question which was set.
It quotes the headway formula without a diagram to explain derivation.
It uses what is termed an "aspect ratio" which is not explained or justified.
It calculates the minimum headway for 3 aspect signals which was not required in the 2004 paper.
It does however also determine the acceptable range of spacing that does answer the question related to signalling the layout.
It attempts to use the same short cut method for stopping headway, doesn't completely explain what trying to do, but it was a bit better because the "penny did actually drop" with me this time. However it is based upon the 3 aspects being placed at minimum spacing rather than any greater figure that matches what was declared would be used.
Assumption were placed at the end as an after thought, although they had previously been utilised. No comment was made regarding the necessity or not of designing any contingency into the signalling relating
to the declared headway requirement and level of utilisation.
PJW