I'll look at but do have a look at the Study DVD module 2 portion.
1/2. It is unlikely that you'd need 20% contingency, but you should make some allowance. It depends on the service- there often needs to be a margin between what train service is to be advertised to the public and what the signalling must be capable of.
If there is a contractual committment to a train every 180 seconds then would certainly wish to make sure that could signal a train say every 160 seconds; otherwise if train 1 is late then all the subsequent ones will be delayed. Hence there is a vast difference between a requirement for the 2 closest trains in a day to be 3 minutes apart but actually only say 6 trains an hour and where every train is 3 minutes apart and there is no period during which there could be recovery to limit the inmpact of late running.
3. I really don't advise using the DGR method giving a ratio at all. If you do use it as a short cut then you must understand what it really means. It is to do with the minimum spacing determined by the braking consideration and the maximum spacing as dictated by the headway consideration. Look at the Study Pack text and also a Powerpoint presentation included on the DVD re Headway and Braking.
4. Don't understand your question- perhaps it'll become clearer when I look at your attachment.
5. On the Study DVD there are attempts at quite a few layouts and indeed there are even some on this forum.
6. This should be explained in the Study Pack; if there is something you do not understand then try to be moree specific in order that we can help (and indeed amend the Study Pack for future)
Also see this post on signal placement
1/2. It is unlikely that you'd need 20% contingency, but you should make some allowance. It depends on the service- there often needs to be a margin between what train service is to be advertised to the public and what the signalling must be capable of.
If there is a contractual committment to a train every 180 seconds then would certainly wish to make sure that could signal a train say every 160 seconds; otherwise if train 1 is late then all the subsequent ones will be delayed. Hence there is a vast difference between a requirement for the 2 closest trains in a day to be 3 minutes apart but actually only say 6 trains an hour and where every train is 3 minutes apart and there is no period during which there could be recovery to limit the inmpact of late running.
3. I really don't advise using the DGR method giving a ratio at all. If you do use it as a short cut then you must understand what it really means. It is to do with the minimum spacing determined by the braking consideration and the maximum spacing as dictated by the headway consideration. Look at the Study Pack text and also a Powerpoint presentation included on the DVD re Headway and Braking.
4. Don't understand your question- perhaps it'll become clearer when I look at your attachment.
5. On the Study DVD there are attempts at quite a few layouts and indeed there are even some on this forum.
6. This should be explained in the Study Pack; if there is something you do not understand then try to be moree specific in order that we can help (and indeed amend the Study Pack for future)
Also see this post on signal placement
(23-08-2011, 09:02 AM)dilip421 Wrote: Hello sir,
We have solved 2008 paper by the guidence of our seniors. please go through our attachement & give the corrections.
we have some doubt,
1) Why we required 20% of contigency...?
2) How we are calculating this 20% contigency...?
3) After taking ratio how to decide its 2aspect,3aspect or 4aspect is any written document is provided...?
4) For stopping train why we have to take the total time taken by the stopping train....?
5) The way of explaining in the 2008 layout attachment is correct to write in the exam or we have to show the diagram...?
6) After decideing the aspect how to start the signalling the layout...?
please explain us or forward any solved signalling layout plan. we are got stuckup in that.
Regards,
GDK
PJW