2005 Layout - Part 1

[Peter]

Peter,

Please help see the headway calculation.

Thanks in advance.

Best regards,
Arnut

Your non-stop headway calculation looks very good with the following comments.

You have clearly done this as an exercise rather than under exam conditions and set it all out very well (which there is nothing wrong with), but as you move on, you will need to be mindful that the time that you have spent writing out conversion tables etc. will not be there for you in the exam.

Having laboriously written out the conversions, you have gone on to merely quote the N = DGR/SBD formula. While this is a tool which gives you an answer, it will not be adequate to quote this in the exam without explanation. You need to demonstrate to the examiner that you understand what this is showing. What I have done in the past is to use the formula for myself in rough working to tell me what the answer needs to be (say 3 aspect), and then on the exam paper to show why other options would not be appropriate.

You have correctly used the headway speed when considering how far the train gets in a given time, and correctly used the maximum speed when setting the minimum signal spacing.

There is no right or wrong answer for the amount of contingency you add in, but I notice for non-stop you have 20% and for stopping you have 10%. Was there a reason that you have not been consistent?

For your stopping calculation, I am not sure that you have quite grasped what you are calculating. You have effectively assumed that the station stop will be co-incident with a signal. While this is often the case, it is not always so. You have calculated the time for the train to come along at speed, brake, dwell and clear the overlap but at the time you have calculated, the train in question has not yet attained its normal running speed and hence a following train would still be catching it up.

I am unclear what calculation you have done for time e since you have
(180 + 200) = 1/2 x 0.5 x t2 and declared therefore that t=39 which is not correct arithmetic.

For stopping headway, you are trying to find out how long a train would take to move thorough an area without it impacting on a following train. You therefore need to consider the time it takes to brake, dwell and accelerate back to full speed compared with the fact that the following train is not stopping. You have almost done this, but your train is not yet at full speed when you stop your calculation.

Have another look at what you have worked out for this and see whether your conclusions are still the same.

I will have a look at your layouts shortly - I have a 5 year old perstering me to go an play right now!