22-09-2009, 09:58 AM
Given your headway calculation outcomes, the main signals that you have placed appear to be consistent with the numbers. The fact that with those numbers you appear not to have ended up with any significant conflicts with fixed infrastructure would appear to be a blessing for the student and quite untypical of the normal layout!
The main comments on the layout are to with how you have used signals and their form rather than issues of spacing, braking and aspect sequences.
The remit was to allow trains to access the stabling siding with a train on the branch. At the moment to get a train into the siding, you would go from 10, 12 or 14 via the points to the branch, but you have to go behind 305 signal which takes you past 504 and hence on to the branch into the "one train working" section, hence you cannot meet the remit requirements.
305 signal is shown as being able to show R or G. What about routes into the bay and what if the next signal on the main line is R?
I was not entirely clear how your branch worked. It looks like some sort of one train working system, but I was not sure how you prove a train has arrived at station B and is then proved to have gone to the yard. At the other end, normal OTW systems are proved by a sequence of TC operation and a treadle, but no treadle is shown
For 10 and 12 signals, you have given them SIs rather than PLJIs. Although these are MAR for the turnout route, I would normally expect them to be PLJIs for such a signal. Conversely, 7 and 157 have PLJI for all routes. This is a problem for the route into the bay as this is not allowed.
You have numbered parallel signals with the same final digit. While this was common practice in the past, this is specifically not allowed.
You need to revise the meaning of a Limit of Shunt. These are for the end of shunt movement authority where the movement are in a direction that does not have any other signalled moves. There are no circumstances where you can pass an LOS in normal operation. With this in mind, how would you get a train through the run round loop (702) or out of the yard (713)?
In the yard, you have lots of motor points, but no track circuits. If the points are remotely operated, there needs to be some indication / control to prevent them being moved with a train on them.
Trap points. In the goods loops you have mentioned about trap points and used a symbol which I took to be traps and with what looks like a TC interrupter. You used a similar points symbol at 202 points in the yard but I was not clear whether you intended all of the points in the yard to be have trap points - you have n them with a sort of throw off but only numbered one end, so I assume they are not. This being the case, given the requirement to allow shunting in the yard while the branch is being used for passenger moves, how is this protected. Probably best to look at some trapping protection at the interface between the yard and the running line.
I am not clear about your method of working for the run round via the down main at E. You appear to be bringing the train into the loop, running the engine round and then propelling it onto the down main before setting off to the destination. what is the purpose of the "preset shunt signal" and the call on associated with 11 signal. I suspect that the examiners intention is that once the engine has run round, the train would set off in the up direction out of the loop. Although the arrows show running moves only in the down direction, I take this to mean that there are no signalled moves into the loop in the up direction. I do not consider setting off from the loop in the up direction to be in conflict with this.
Some more minor details: Some TC joints are missing (AJ/AK, BY/BZ); some point numbers missing; point numbering sequence and signal numbering sequences are usually kept separate - they are intermixed here; the GPLs in the siding appear to have been positioned to be parallel with the signals on the main line. This is not necessary and wastes a lot of valuable track in the siding; you'll need to check this one, but I think there is a requirement that if a route indicator is provided for shunt signals, all destinations need to be shown (ie 704 should probably have 5).
The main comments on the layout are to with how you have used signals and their form rather than issues of spacing, braking and aspect sequences.
The remit was to allow trains to access the stabling siding with a train on the branch. At the moment to get a train into the siding, you would go from 10, 12 or 14 via the points to the branch, but you have to go behind 305 signal which takes you past 504 and hence on to the branch into the "one train working" section, hence you cannot meet the remit requirements.
305 signal is shown as being able to show R or G. What about routes into the bay and what if the next signal on the main line is R?
I was not entirely clear how your branch worked. It looks like some sort of one train working system, but I was not sure how you prove a train has arrived at station B and is then proved to have gone to the yard. At the other end, normal OTW systems are proved by a sequence of TC operation and a treadle, but no treadle is shown
For 10 and 12 signals, you have given them SIs rather than PLJIs. Although these are MAR for the turnout route, I would normally expect them to be PLJIs for such a signal. Conversely, 7 and 157 have PLJI for all routes. This is a problem for the route into the bay as this is not allowed.
You have numbered parallel signals with the same final digit. While this was common practice in the past, this is specifically not allowed.
You need to revise the meaning of a Limit of Shunt. These are for the end of shunt movement authority where the movement are in a direction that does not have any other signalled moves. There are no circumstances where you can pass an LOS in normal operation. With this in mind, how would you get a train through the run round loop (702) or out of the yard (713)?
In the yard, you have lots of motor points, but no track circuits. If the points are remotely operated, there needs to be some indication / control to prevent them being moved with a train on them.
Trap points. In the goods loops you have mentioned about trap points and used a symbol which I took to be traps and with what looks like a TC interrupter. You used a similar points symbol at 202 points in the yard but I was not clear whether you intended all of the points in the yard to be have trap points - you have n them with a sort of throw off but only numbered one end, so I assume they are not. This being the case, given the requirement to allow shunting in the yard while the branch is being used for passenger moves, how is this protected. Probably best to look at some trapping protection at the interface between the yard and the running line.
I am not clear about your method of working for the run round via the down main at E. You appear to be bringing the train into the loop, running the engine round and then propelling it onto the down main before setting off to the destination. what is the purpose of the "preset shunt signal" and the call on associated with 11 signal. I suspect that the examiners intention is that once the engine has run round, the train would set off in the up direction out of the loop. Although the arrows show running moves only in the down direction, I take this to mean that there are no signalled moves into the loop in the up direction. I do not consider setting off from the loop in the up direction to be in conflict with this.
Some more minor details: Some TC joints are missing (AJ/AK, BY/BZ); some point numbers missing; point numbering sequence and signal numbering sequences are usually kept separate - they are intermixed here; the GPLs in the siding appear to have been positioned to be parallel with the signals on the main line. This is not necessary and wastes a lot of valuable track in the siding; you'll need to check this one, but I think there is a requirement that if a route indicator is provided for shunt signals, all destinations need to be shown (ie 704 should probably have 5).