Selection of Signalling

[NJK]

Dear Members,

If the required Non stopping & stopping headway can be achieved by 3 aspect signals means, the the same Non stopping & stopping headway can be achieved by 4 aspect signals also.

During headway calculation, normally I start with 3 aspect, when it is fail to meet the required headway then attempt with 4 aspect.

During examination, shall I attempt my calculation directly to 4 aspect instead of initially attempting with 3 aspect ?

I feel it save exam time and also avoid critical situation like transition required from 3 to 4 aspect to meet the operating requirements.

My question fully focus exam point of view. Attempting this method leads to any negative feedback like reducing marks ?

Kindly clarify and if I am wrong kindly correct. Thanks in advance

Regards,
NJK

[Peter]

I took the approach you outline when I took module 2 because you need to prove that 3 is not adequate in order to meet the requirement that your solution is "economic". If you found that 3 was adequate, you would need to show that 2 was not, so starting at 3 is the best option.

My suggestion is thetefore that you budget in your exam plannong cor doing two sets of basic non stop calcs.

[Jerry1237]

You will find the layout fits on scheme very well and you will struggle with others. It is not always possible to use 4-asp where 3-asp is required.

[PJW]

You will find the layout fits on scheme very well and you will struggle with others. It is not always possible to use 4-asp where 3-asp is required.

Expect to use at least 2 different form of signalling for different areas of the layout, perhaps branch and mainline or perhaps 4 aspects around the main station on the mainline and 3 aspects further away in the plain line section.

If you decide for example 4 aspects throughout it should always work, but you'll lose marks where this is not the economically viable solution.
Also because the quantity of signals needed for a 4-aspect solution is nearly doubled, you'll waste time adding all these and thus have less time available to gain other marks. Yes the need to transition 3 to 4 and vice versa does take effort, but if you arrange things deliberately to avoid, you can expect the examiners to realise what you are doing; there will be marks available for showing you can do the activity, so if you bottle out and avoid it then you will not get those marks.

Hence you do need to do properly- take a short-cut and all you are doing is limited your ability to gain the appropriate marks.