2005 Layout - Part 1

[Peter]

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?

If I understand well, it needs only 10% contingency in reality. 20% is giving too much. I saw the comments from PJW from other attempts and he suggests to have only 10%.

As I said, there is no right or wrong answer, but if you have stated the country's practice that you are following, you need to pick a value that is consistent with it and state what factor you have included. 10% is a reasonable value.

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 not clear. Time to clear the overlap before to be normal running speed is not enough? Do I really need to provide the time to catch up normal running speed?

Yes. Otherwise, at the moment that the first train has cleared the overlap, if the following train is just before the sighting point, it gets a clear aspect, but it will be going faster than the first train and hence will be getting closer to it, hence at the next signal section, the second train will see a restrictive aspect as it will be closer to the first train.

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.

Actually I could not understand what I made it wrong. 380 x 2 / 0.5 = t2(power of 2) then t approximately = 38.98s or 39s.
Section e meant to be the the time to clear overlap(Track length 200m and overlap distance 180m)

Apologies, you are right. I am not sure what I thought was wrong there!

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.

I am totally confused what the way would be to calculate the stopping headway. Can you give me the example? I have studied other attempts and they seem to look like my attempt. Did I miss something?

You have done it this fine in the other attempts that you have made, in this thread and the one that Reuben has commented on - ie you have considered the full time injected into the time to run through the section.

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!

I look forward to seeing your comments please...

Sry for poor English.

You do not need to apologise, it is far better than my Thai would be!

Peter

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I have made Route box and new headway calculation. Could you please kindly check and advise?

Thanks
Arnut

Your headway calculation is very good here.

A couple of things that could improve it:
You have shown that the headway can be met with three aspect signalling at minimum braking with a fair degree of contingency. You have not made a comment about what the maximum over braking allowance is for your practice nor calculated what the maximum is without breaking the headway requirement.

Having made the comparison with the four aspect signalling, you have not actually said which scheme you would adopt - this would probably be self evident from what you draw on your layout, but more importantly you have not said WHY. In the case of the three aspect signalling with the stopping headway, the margin for contingency is smaller than for the non stop and, taking account of the fact that you would probably not want to (or be able to) put all signals at minimum braking, the margin would be even smaller, so based on that constraint, you may decide that opting for four aspect signalling is better.

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Hi Guys

May I have any review or comments please?

My attempt is based on UK Mainline practice

Best regards
Arnut

A very clear and well set out attempt.

It is the victim of a cut line, but I cannot see properly what you have done with the signal that 117 reads up to - at some point you have gone from a 4 to three aspect sequence and I am not sure that you have quite done this correctly. I assume the signal after 117 to be a three aspect signal since i can see your "Y>R" annotation. From the positions on the plan, the post to post distance here is about 700m so for a three aspect Y>R, this would be insufficient. I would expect to see a G,Y,YY signal somewhere in the transition.

You have put a ROL on 118 signal which is not the correct use of ROL - it is for a warner route up to a convergence, not for bringing a signal closer to a facing junction.

I may have got this wrong, but the route boxes that you posted do not appear to match up - for instance, 110 signal is shown here with a SI, but you have JI1 and JI4 in the route box attachment. Similarly, 107 has no MI associated with it on the plan, but has an entry for MI in the route boxes.

I am afraid I will have to leave it there for now.

Peter