29-01-2013, 08:42 AM
It really doesn't matter. The 10% figure is "plucked out of the air" and so, whereas I agree there is a small amount of ambiguity, any discussion whether the calculation is based on 136s or 135s is irrelevant- personally I'd do the division and therefore utilise 136s, but IT DOESN'T MATTER.
You have the concept- now move on.
You have the concept- now move on.
(29-01-2013, 04:55 AM)kiran218 Wrote: Dear PJW,
If contingency is provided for headway is 10% and headway time is 150sec. Practical headway time we have to take 150/1.1=136 or 150-10%=135 which is we have to fallow in the exams. what is the difference between two.
with regards,
kirankumar
(28-01-2013, 03:43 PM)PJW Wrote: The whole point is that it is a judgement call, depending on all the circumstances; for IRSE exam I would not be overly concerned whether put a 10 second contingency or any reasonable percentage say from 2 - 20 per cent. Understand WHY we put a margin and the factors that determine what might be appropriate; don't worry re the ABSOLUTE VALUE in any particular circumstance!
(28-01-2013, 11:33 AM)kiran218 Wrote: Hi NJK,
1o percent of contigency is required for headway time. Under what conditions we have to fallow this?
With Regards,
KiranKumar
(27-08-2012, 05:26 AM)NJK Wrote: Dear Members,
I have attempted module 2 2005 layout calculation. Kindly review it and give your comments for my further enhancement.
Thanks in advance.
Regards,
NJK
PJW

