(21-09-2011, 10:52 AM)yuvaraj.narasimmalu Wrote: please comment on the calculations for 2009 layout for me to improve..
It was quite concise and clear which is good; suggest you read my comments in conjunction with those made earlier in this thread relating to other people's attempts.
Item 3. You state "required headway distance". Actually it is the maximum distance at which two trains moving at the timetabled speed are sufficiently close together that just achieves the specified headway time.
You will not get many marks by quorting the ratio DGR/BD.
The examiners have made it clear that they do not favour this methodology and particularly, as in your case, when the student fails to explain where the formulae comes from and just quote "magic numbers" from thin air. You definitely need a diagram and explain the physical significance of the ratio and why certain values imply the choice of a certain form of signalling.
The good thing was though that having deciided 3 aspect signalling is suficient then you didn't go on to waste time re 4 aspect signalling, like so many do.
Item 4.
Should have made clear this is headway time for 3 aspects at the closest spacing.
Item5.
Should explain why the limit re degree of over-braking; i.e what the risk is.
Also remember that you do not only need to respect this when determining the maximum, but also the maximum spacing that still achieve the headway. You never showed that signals spaced at 2153m would achieve the 2.5 mins.
Your diagram has no axes to make clear what it is representing. In that respect my comments would be very similar to other recent attempts. Basically ok but you need to take more effort into explaining that you are comparing the time taken for a stopping train compared with a non-stop train and then demonstrating that this is less than the "headroom" that the signalling provides fot the through traffic.
Also there is a disconnect between this and the range of possible signal spacings 1511-2153m that you quoted earlier. You should see whether the need to achieve the stopping train headway imposes any smaller maximum spacing for the signalling.
Next section headed "Non-stopping" but surely relates to stopping
PJW