2005 Layout - Part 1

[PJW]

Hello PJW,

Appended please find my attempt on the 2005 layout.

Thank you once again for your time and effort especially your superb turnaround times.

I look forward to your comments
Cheers
Alex

Calculations:

For the exam you don't actually need to do all the braking calculations you have done. All very well when using a spreadsheet and time isn't of the essence, but in the exam restict yourself to that which you really need. Suggest this is normally just the passenger on the mainline and if there is a branch with a different permissible speed the value for that line as well.

The wording of the question in 2005 was:
Determine theoretically, either by calculation or graphically, appropriate signal spacings for the braking characteristics and the intensity of traffic on offer. All calculations and graphs
must be shown.

Non stopping:
Generally good.
Should have explained the rationale for the 1.33 SBD limit n signal spacing.
You wasted time again by calculating Hd3 and Ht3; effectively doing the same calculation as you had just done backwards and not surprisingly came up with the 125sec value that you had declared in the first place.

Stopping:
Generally good but
a) diagram would have been better if showed the platform,
b) diagram shows braking in portion c commencing at signal 3 whereas your calculations obviously places the transition betwen portion b and portion c significantly past this. To be honest the diagram is really what would happen but that would make c 1095m as it is effectively a signal section but the brakingrate would be less than 0.5m/s/s if decelerating from 100km/h over that entire length. However your calculations assume that driver does not brake on passing 3 and leaves to last minute and thn brakes at maximum rate. This approach makes calculations easier but you should state that this is an approximation and in reality the headway achieved will actually be less (can be part of your rationale for that 20% contingency); certainly the diagram and the calculations must match
c) you should explain the derivation of the 1255m mentioned in your note 2.

Notes
General notes very good.

Working of freight trains etc. Explanation in the exam can be much more brief; I think you have followed my approach when explaining it to students who may not understand; in the exam all you have to do is outline it to show the examiner that you do understand.
I would say something much more compact like:
Freight left in Down Slow platform at C, engine runs around via 121, 305, 122, 116, 301, re-couples and propels train into turnback siding waiting at 122 for a return path to station B.

HOWEVER I don't actually think that is right (above I have described the same move that you did for comparison) in this instance.
a) The turnback siding is fundamentally for the passenger service terminating at C.
b) We have to assume that the freight is originating / terminating at C (unlike the prevous layout you did where it was just needing to change direction to access a different railway line). Hence we must assume that the trin needs to go into / come out of the Down Siding.
Therefore I would say:
Train arrives in Down Slow platform at C; sets back into Down siding utilising 114's PL. After loading, signalled into platform again using 303. Loco detaches and run around via 121, 122, 116, 301 to re-attach and then signalled towards station B from 114.
Looking at station B it is evident that there are no sidings etc. Hence think need to explain to examiners our assumption:
Since there are no freight facilities depicted on the plan at B it is assumed that the freight must be intended to pass through B and continue to somewhere beyond A