I am on IRSE Convention at present, so unfortunately will not have opportunity to respond properly to this for several days; indeed I am getting quite a few other requests for last minute help in the run-up to the exam and have a backlog of such to deal with.
Your calculations for non-stop indicate that 3 aspect insufficient and 4 aspect sufficient. Therefore for stopping, just consider the 4 aspect case with the intention of showing that this provides the capacity.
I know that your figures for this suggest that it is not achieved and therefore there would be no solution- this may or may not be the case but there is certainly no value in proving that 3 aspects don't achieve as they are already ruled out by the non-stop calculations.
Primary problem is that you are not calculating the stopping headway correctly. You have based this on:
Ht4= Ht4(1) + decelerating time + dwell time + accelerating time.
Wearing my critical examiner hat, I'd say that I do not know what the terms you have used all mean, where this equation comes from etc. You haven't demonstrated to me that you understand what you are calculating or that you understand what the signalling constraint re stopping headway is. If you calculate the wrong thing then it is not surprising if the numbers don't work out.
I suggest you draw some diagrams and really try to think through what you have stated, what you wrote really meant and what you really should have written. This should both increase your understanding and allow you to find your error and correct.
Look at the other attempts on this website regarding the various different stopping headway calculations and the comments made upon them. Working through these should help and actually assist your understanding more than if I just corrected your calculations.
Your calculations for non-stop indicate that 3 aspect insufficient and 4 aspect sufficient. Therefore for stopping, just consider the 4 aspect case with the intention of showing that this provides the capacity.
I know that your figures for this suggest that it is not achieved and therefore there would be no solution- this may or may not be the case but there is certainly no value in proving that 3 aspects don't achieve as they are already ruled out by the non-stop calculations.
Primary problem is that you are not calculating the stopping headway correctly. You have based this on:
Ht4= Ht4(1) + decelerating time + dwell time + accelerating time.
Wearing my critical examiner hat, I'd say that I do not know what the terms you have used all mean, where this equation comes from etc. You haven't demonstrated to me that you understand what you are calculating or that you understand what the signalling constraint re stopping headway is. If you calculate the wrong thing then it is not surprising if the numbers don't work out.
I suggest you draw some diagrams and really try to think through what you have stated, what you wrote really meant and what you really should have written. This should both increase your understanding and allow you to find your error and correct.
Look at the other attempts on this website regarding the various different stopping headway calculations and the comments made upon them. Working through these should help and actually assist your understanding more than if I just corrected your calculations.
(13-09-2012, 05:37 AM)mustafa Wrote: hi PJW,
can you please send your comments in calculations and the purpose of posting is if both 4-aspect and 3-aspect headway is not within the required headway(even we didn't deduct contingency) then what is the solution?
clearly we know each step in the attached file but we did each possible step for searching required headway,
also I wanted to know whether the procedure we followed for solving the headway and breaking calculations is wrong?
if so please send the correct procedure in your opinion
PJW