(24-06-2010, 03:15 PM)KonduriRaghavakumar Wrote: Thank you, sir, I again reattempted this question no.8 please check it sir. I am gaining knowledge about these calculations from the study pack only. It is some what feeling difficult to me but i am trying sir.
I think the Study Pack should be enough, but also look on this website; in particular there are more example attemts of stopping headway here.
You need to be careful to distinguish between
max permissible speed used for braking and
timetabled running speed used for headway. When you modified the sheet I think you rather confused yourself re whether 44.7m/s equated to 100mph or 80mph so it was difficult to see what you were doing.
The braking rate for freight in this example was not the same for passenger trains, so its braking distance is 1440m. However I agree that the braking distance for passengers is 200m, so that is the dominant factor rethe minimum spacing.
You should have done two calculations for the headway requirement to ensure that with a signal spacing as above that you could deliver the passenger (by day) and the freight headways (by night) demanded. You should use the 100m length for the former and the 400m for the latter. have a go at this bit and determine which is the more onerous.
Then you will be able to tell what is the maximum signal spacing you can permit. i suggest for tis question you are best off not trying to use the "DGR" method as you are likely to confuse yourself.
One other issue- be careful not to get confused between "baraking distance" and "signal spacing"; they are relaed but not the same. In 3 aspect signalling the spacing cannot be less than the braking; in 4-aspect signalling, the distance between alternate signals cannot be less than the braking. Go back and read what you wrote........
As I said before, you started with a hard one; noone else has had the guts to have an attempt at it and it is designed to ensure that you are clear re what figure you are using where.
Keep plugging away at it, re-read the Study Pack section in the light of what you have learned. You are on the right lines, but not quite there yet