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First try at the exercise
#1
Hi Signalling Professionals:

The attached files are my first attempt for the signalling layout exercise and headway calculation for single line railway.
Please check my work, I apologise if my work is totally out of the track.



thanks


william
Reply
#2
This is an interesting question that I'll attempt to look at soon.
I don't remember this being an actual IRSE exam question, but nothing wrong with that and there is no reason why if shouldn't have been set.
Where did it come from?
What precisely was the wording of the question- presumably you were given a blankk layout on which you needed to position some signals in order to comply with some nominated criteria?

(31-10-2011, 04:04 AM)onestrangeday Wrote: Hi Signalling Professionals:

The attached files are my first attempt for the signalling layout exercise and headway calculation for single line railway.
Please check my work, I apologise if my work is totally out of the track.



thanks


william

PJW
Reply
#3
Yes, this is an exercise question for signalling layout of a single line railway (given a blank single line layout).

The question given is as below:

1. Signal the layout shown in the Single Line Layout.

Position the signals fixed by the layout first. Then position the remaining signals.

Assume
Max Train length: 200 metres
Deceleration: 0.7m/s2
Brake delay: 6 seconds
Maximum train speed: 100k/h
Maximum line speed: 120k/h

2. Calculate the headway on the line for:
a. Following trains
b. Opposing trains.

Clearly show the calculations used to arrive at your solution.



please check my work, if there's anything wrong as I am not very experienced in signlling a layout, but I wish to further extend my knowledge on various aspect of Railway Signalling.


thanks





(31-10-2011, 06:50 AM)PJW Wrote: This is an interesting question that I'll attempt to look at soon.
I don't remember this being an actual IRSE exam question, but nothing wrong with that and there is no reason why if shouldn't have been set.
Where did it come from?
What precisely was the wording of the question- presumably you were given a blankk layout on which you needed to position some signals in order to comply with some nominated criteria?

(31-10-2011, 04:04 AM)onestrangeday Wrote: Hi Signalling Professionals:

The attached files are my first attempt for the signalling layout exercise and headway calculation for single line railway.
Please check my work, I apologise if my work is totally out of the track.



thanks


william

Reply
#4
OK sorry- I see now that you had put the question in with your answer.
Looking at your signalling, there are some inconsistencies and you have rather too many signals overall.

Station A
a) should have signalled the terminal platform as well
b) need a signal to control admission to the station (both from left and the right)

Loop A1
On the approach from the left there is no home signal with junction indicator and giving a yellow reading up to the loop starting signals, although you have one from the right ok.
This home also correctly has a distant at approx 51km but the signal on its approach near 52km is superfluous I believe (if it is to be there then it would itself need a distant braking distance on its approach).
Same applies in opposite direction excepy you have shown both as Red/Green whereas the one near 52km should be a yellow/green distant.


Other sections similar comments, but look at the end portion to station B.
The section from loop A3 seems to have 4 sections since all shown as Red/Green. I am going to assume that you meant there to be 2 sections with two of the signals intended to be distants. Even so that is odd, because the spacing is such that the signals could all have been 3 aspects, but I'll ignore and instead assume that there is
1) one section between loop A3 and 61km
2) one section between 61km and 63km
3) one section between 63km and the stop block at station B.
The question is WHY?
Once a train has left loop A3 then it will need to run to station B and then come back again to loop A3 in order to pass the next train that is en route to station B. There isn't value in allowing more than one train between A3 and B because the following train would then trap the one which preceded it.
Hence I think you need a home red/green signal at 63km and a distant yellow/green at 62km but no other signal for that direction from the starting signals at A3.
In the opposite direction you need a starting signal at the platform end of station B, the distant which you have correctly placed at 60km and the 3 aspect home which you have correctly placed at 59km but none of the others.

If we make the assumption that all trains on the branch go the full length to B (seems particularly obvious since the passing loops do not even have platforms), then there is little value in providing signalling on the line from A3 back to A which would support a significantly higher capacity than the section A3 to B this may be something to return to once we have tackled Q2. This is why I said you had superfluous signals earlier.

I suggest you should draw a graph of the timetable.
Make the horizontal axis the distance from A to B and mark loops A1, A2, A3 in their scale positions.
Make the vertical axis the time and draw in the largely diagonal line representing train 1 proceeding at it nominal speed but with a period of say 5 minutes dwell (i.e. vertical portion within the otherwise constant gradient diagonal line) at each station (I have selected this time to reflect that in reality there will be time lost during acceleration and deceleration periods as well as incorporating a bit of "recovery allowance" waiting at the station).
Then give a 5 or 10 minute allowance for the train at B to reverse direction and mark its path on the return journey.
Having worried about that train, take a different colour and now draw in a similar path for a second train. I suggest that you start this by considering loop A3 and making it start towards B at the same time as train 1 was starting towards A. Now draw the whole of its journey (i.e. both prior and after).
Now choose another colour and draw in similarly for train 3. Do make sure that the trains only pass each other when at a loop or station A; anywhere else is only single track so it will not be a pass but a head-on collision!
Carry on doing this until you can't squeeze any more train paths in and therefore your timetable is maximising the use of the line.

OK this wasn't precisely what you were asked to do in this exercise, but you do need to do it as a learning exercise, so that you are not temped to put rather more signalling on the plan than could possibly be needed.

We can then later have a re-look at you numbers when we have a more realistic Signalling Plan and can see their significance. However the numbers you did in the Q1 part of the question look well presented and reasonable.

(31-10-2011, 07:19 AM)onestrangeday Wrote: Yes, this is an exercise question for signalling layout of a single line railway (given a blank single line layout).

The question given is as below:

1. Signal the layout shown in the Single Line Layout.

Position the signals fixed by the layout first. Then position the remaining signals.

Assume
Max Train length: 200 metres
Deceleration: 0.7m/s2
Brake delay: 6 seconds
Maximum train speed: 100k/h
Maximum line speed: 120k/h

2. Calculate the headway on the line for:
a. Following trains
b. Opposing trains.

Clearly show the calculations used to arrive at your solution.



please check my work, if there's anything wrong as I am not very experienced in signlling a layout, but I wish to further extend my knowledge on various aspect of Railway Signalling.


thanks





(31-10-2011, 06:50 AM)PJW Wrote: This is an interesting question that I'll attempt to look at soon.
I don't remember this being an actual IRSE exam question, but nothing wrong with that and there is no reason why if shouldn't have been set.
Where did it come from?
What precisely was the wording of the question- presumably you were given a blankk layout on which you needed to position some signals in order to comply with some nominated criteria?

(31-10-2011, 04:04 AM)onestrangeday Wrote: Hi Signalling Professionals:

The attached files are my first attempt for the signalling layout exercise and headway calculation for single line railway.
Please check my work, I apologise if my work is totally out of the track.



thanks


william

PJW
Reply
#5
Hi PJW:

Thanks for taking time to review my work and it gives me great help. Be honest, my signalling experience is only limited to ‘High Class Level’ of signalling equipment, that is ATC (so virtually there is no lineside signal installed on the wayside) and high speed rail signalling system which is high costly build compare to ‘normal’ signalling system. So I am poor at considering about other real-life Signalling System that has been used in conventional railway line, but I wish I can broaden my view on the railway system as a whole.

Attached jpg file is the updated version of single line layout which I have done. The suggestion you gave I’ll try later to see how it goes.


Thanks
william

(31-10-2011, 11:43 PM)PJW Wrote: OK sorry- I see now that you had put the question in with your answer.

Looking at your signalling, there are some inconsistencies and you have rather too many signals overall.......


I suggest you should draw a graph of the timetable. ....
Reply
#6
Yes, that diagram is now looking much better.
The only obvious thing that you have missed is that the signals at the left hand end of loop A1 need to be 3 aspects so that they can show a caution in circumstances in which the signal controlling admission to station A is at red (need also to consider of braking distance and, if not, what to do about this)


I am sure that by working through this question you'll gain an in sight into the signalling of a very different railway to the type you are used to.
It will therefore prove its value as an exercise.


(01-11-2011, 08:20 AM)onestrangeday Wrote: Hi PJW:

Attached jpg file is the updated version of single line layout which I have done. The suggestion you gave I’ll try later to see how it goes.


Thanks
william

(31-10-2011, 11:43 PM)PJW Wrote: OK sorry- I see now that you had put the question in with your answer.

Looking at your signalling, there are some inconsistencies and you have rather too many signals overall.......


I suggest you should draw a graph of the timetable. ....

PJW
Reply
#7
There is nothing wrong with not using lineside equipment but the fact that in-cab signalling or ATC is being employed needs to be stated clearly.


(01-11-2011, 08:20 AM)onestrangeday Wrote: Hi PJW:

Thanks for taking time to review my work and it gives me great help. Be honest, my signalling experience is only limited to ‘High Class Level’ of signalling equipment, that is ATC (so virtually there is no lineside signal installed on the wayside) and high speed rail signalling system which is high costly build compare to ‘normal’ signalling system. So I am poor at considering about other real-life Signalling System that has been used in conventional railway line, but I wish I can broaden my view on the railway system as a whole.

Attached jpg file is the updated version of single line layout which I have done. The suggestion you gave I’ll try later to see how it goes.


Thanks
william

(31-10-2011, 11:43 PM)PJW Wrote: OK sorry- I see now that you had put the question in with your answer.

Looking at your signalling, there are some inconsistencies and you have rather too many signals overall.......


I suggest you should draw a graph of the timetable. ....

Le coureur
Reply


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