01-03-2012, 09:16 AM
Hello,
I have not checked the maths or algebra as others are more qualified to do that. However, I do have some comments on your comprehensive answer and some of the conclusions.
1) Time is a killer in exams and what you've written seems to be a little excessive for the marks awarded. There is no need to repeat equations. Derive them once and give answers for other examples.
2) The definition of headway time is incorrect but the maths seems good. Headway is equal to Overlap plus sighting distance plus distance from first green aspect to the red...
3) 10% margin on 1972m does not make 2000m but 2169.2m - however, the question states no margins.
4) There is no need to discuss other options such as two aspect (which is unlikely to support the quoted service anyhow).
That said, it was a good attempt but brevity with detail and clarity is what gets marks and supports exam technique for this question.
I have not checked the maths or algebra as others are more qualified to do that. However, I do have some comments on your comprehensive answer and some of the conclusions.
1) Time is a killer in exams and what you've written seems to be a little excessive for the marks awarded. There is no need to repeat equations. Derive them once and give answers for other examples.
2) The definition of headway time is incorrect but the maths seems good. Headway is equal to Overlap plus sighting distance plus distance from first green aspect to the red...
3) 10% margin on 1972m does not make 2000m but 2169.2m - however, the question states no margins.
4) There is no need to discuss other options such as two aspect (which is unlikely to support the quoted service anyhow).
That said, it was a good attempt but brevity with detail and clarity is what gets marks and supports exam technique for this question.
Le coureur