Post by Deleted on Jan 27, 2015 22:11:41 GMT
Hi,
I've been spending some time today trying to work out how the Jubilee line is organised under TBTC and what the various sub-systems do and how it all works.
As far as I can make out the basics of the system are thus:
The inductive loops are placed on the track and are used for communications between the VOBCs on the train and the VCC. The train uses aerials located on trailer cars to send and receive messages. The train communicates its position to the VCC every second, the VCC sends the train instructions every three seconds. The loops cross over every 25 metres, which is done to help the train calculate its position accurately. The loops are a maximum of 1 kilometre long. This provides boundaries between loops so that if one loop is broken or otherwise becomes defective, any trains travelling over that loop will be able to reach a working loop relatively quickly and can reenter the system.
The VOBCs (Vehicle On Board Controllers), of which there are two, are located on the train (one at each end). At any given time, one will be active and the other passive (unless one has failed). As well as communicating with the VCC as described above, the active VOBC is responsible for the actual movement of the train in compliance with the instructions it receives from the VCC. It provides the ATO functionality, as well as ATP. In other words, it interfaces between information received from the VCC and movement of the train, or information provided to the Train Operator (in this case it, of course, also ensures that the Train Operator responds to the information correctly).
The SCS's (Station Controller Subsystems) are located on site, in the signalling equipment rooms (SERs) and are responsible for such things as the physical movement of points, emergency stop implementation, etc. They communicate with other SCS's, as well as the relevant VCC. In essence, the VCC gives instructions to the SCS's and the SCS's translate those instructions into physical responses - in much the same way as the VOBCs do for the trains. In this way they are quite similar in function - as I understand it - to the equipment in the old relay rooms.
The VCCs (Vehicle Control Centres) are located within the SCC at Neasden. There are, I believe, five of these and they each look after a different section of the line. As is presumably quite obvious now, these house the equipment that provides most of the signalling instructions and essentially they run the railway. Thus they are quite similar in overall function to the old programme machines and their later, more advanced, computerised replacements. I believe today's VCCs do a lot more than the programme machines did, are more modern, and control vastly more track, but the basic function is, I think, similar. I gather these have operators, although I've seen it stressed that the VCC operators are not signallers and cannot authorise train movements, so I'm not really sure what they do. Look after them and monitor them I suppose and presumably they can take over various functions as required.
The SMC (System Management Centre) is located in the SCC at Neasden. This is essentially the modern equivalent of the control room and here operators can manipulate the system in various ways to accomplish many of the things that line controllers and signal operators have traditionally done - look after the railway, regulate trains, hold them to time, reroute trains, suspend the service, have trains non-stop stations - all in the service of the travelling public. However much of this is actually done in very different ways. I gather the actual nuts and bolts of carrying these tasks tends to involve making adjustments to the timetable a train is running on, rather than actually setting routes yourself. I presume it is from here that degraded working is managed as well, e.g. authority to select RM, permission to proceed past and up to RM Hold boards, etc.?
The SCC (Service Control Centre) is located at Neasden and is the building which houses the SMC, the VCCs and presumably other things as well.
All of which throws up a few questions I was hoping for your help with:
I've been spending some time today trying to work out how the Jubilee line is organised under TBTC and what the various sub-systems do and how it all works.
As far as I can make out the basics of the system are thus:
The inductive loops are placed on the track and are used for communications between the VOBCs on the train and the VCC. The train uses aerials located on trailer cars to send and receive messages. The train communicates its position to the VCC every second, the VCC sends the train instructions every three seconds. The loops cross over every 25 metres, which is done to help the train calculate its position accurately. The loops are a maximum of 1 kilometre long. This provides boundaries between loops so that if one loop is broken or otherwise becomes defective, any trains travelling over that loop will be able to reach a working loop relatively quickly and can reenter the system.
The VOBCs (Vehicle On Board Controllers), of which there are two, are located on the train (one at each end). At any given time, one will be active and the other passive (unless one has failed). As well as communicating with the VCC as described above, the active VOBC is responsible for the actual movement of the train in compliance with the instructions it receives from the VCC. It provides the ATO functionality, as well as ATP. In other words, it interfaces between information received from the VCC and movement of the train, or information provided to the Train Operator (in this case it, of course, also ensures that the Train Operator responds to the information correctly).
The SCS's (Station Controller Subsystems) are located on site, in the signalling equipment rooms (SERs) and are responsible for such things as the physical movement of points, emergency stop implementation, etc. They communicate with other SCS's, as well as the relevant VCC. In essence, the VCC gives instructions to the SCS's and the SCS's translate those instructions into physical responses - in much the same way as the VOBCs do for the trains. In this way they are quite similar in function - as I understand it - to the equipment in the old relay rooms.
The VCCs (Vehicle Control Centres) are located within the SCC at Neasden. There are, I believe, five of these and they each look after a different section of the line. As is presumably quite obvious now, these house the equipment that provides most of the signalling instructions and essentially they run the railway. Thus they are quite similar in overall function to the old programme machines and their later, more advanced, computerised replacements. I believe today's VCCs do a lot more than the programme machines did, are more modern, and control vastly more track, but the basic function is, I think, similar. I gather these have operators, although I've seen it stressed that the VCC operators are not signallers and cannot authorise train movements, so I'm not really sure what they do. Look after them and monitor them I suppose and presumably they can take over various functions as required.
The SMC (System Management Centre) is located in the SCC at Neasden. This is essentially the modern equivalent of the control room and here operators can manipulate the system in various ways to accomplish many of the things that line controllers and signal operators have traditionally done - look after the railway, regulate trains, hold them to time, reroute trains, suspend the service, have trains non-stop stations - all in the service of the travelling public. However much of this is actually done in very different ways. I gather the actual nuts and bolts of carrying these tasks tends to involve making adjustments to the timetable a train is running on, rather than actually setting routes yourself. I presume it is from here that degraded working is managed as well, e.g. authority to select RM, permission to proceed past and up to RM Hold boards, etc.?
The SCC (Service Control Centre) is located at Neasden and is the building which houses the SMC, the VCCs and presumably other things as well.
All of which throws up a few questions I was hoping for your help with:
- First off, in short, is that the case? Is there anything to add, anything I've missed out, or anything I've simply got completely wrong?
- What do the VCC operators do?
- Who authorises you to select RM and authorises movements in RM?
- Is there an equivalent to a signal operator (I know there aren't any physical signals to operate, but a TBTC equivalent) and, if so, what do they do?
- Finally - and this is really the question I initially set out to answer - where are the boundaries between the five VCCs?
