Aspect Sequence exercise

[onestrangeday]

Hi PJW:

Sure no worries, I am not in hurry, take your time. I just only ask for making sure my thinking is on the track or not.

Once again thanks for your reply.



thanks

Neither do I now. Sorry no time to resolve now- will address this evening I hope

Hi PJW:

thanks for your review. You have mentioned about the attachment, but I don't see it.

I have few questions though:

"a) 11 is shown as a Red/Green not far in rear of 15 (similarly 13 and 17). Probably best not to provide 11- there is no absolute need to have a platform starting signal. If really need 11, then would need to make it "preceeded" bt 15; i.e. prevent 11 for clearing unless 15 already cleared."

Q1: If in this case the platform is very close to the points area, can I eliminate the junction indicator, instead place at the platform with the starting signal ?

or if you eliminate the platform starting signal, how do you show to the driver when to proceed ? (how does this done in UK ?) with signs, or order from train controller ?

Q2:
"I have shown on the attachment how to show the "MAR" Approach Release from Red for those routes which are the slower speed divergence through points."

what is "MAR" Approach release ?



thanks

I think it is easier to discuss the single track layout; the double track layout as drawn has some signals which are underbraked (and indeed others which appear overbraked); it would be best to get to grips with more straight forward arrangement first.
The only issues on the single track layout are:
a) 11 is shown as a Red/Green not far in rear of 15 (similarly 13 and 17). Probably best not to provide 11- there is no absolute need to have a platform starting signal. If really need 11, then would need to make it "preceeded" bt 15; i.e. prevent 11 for clearing unless 15 already cleared.
b) 55 should be a Red/Yellow rather than Red / Green and there should be a red light at the buffers.

I have shown on the attachment how to show the "MAR" Approach Release from Red for those routes which are the slower speed divergence through points. The really important thing to understand is that the signal is at red until the train has passed the previous signal, so the driver will see a yellow there.

I have also drawn out the area around 15/17 to 23/25. On your diagram, can't tell really what is an approach release and what is a pure sequence.

I'll perhaps annotate your examples when I get a chance, but you need to show a transition from one aspect (say red) to a better aspect occurring and against this show the condition which triggers this change. These are shown as vertical lines (and is another reason for drawing the sequence lines horizontal and diagonal rather than vertical)- to distinguish more easily my preference is to show dashed. You will find several examples of this in attachments in other posts in this topic area.