https://irse.signalpost.org/ Mon, 10 Aug 2026 13:14:52 +0000 MyBB https://irse.signalpost.org/showthread.php?tid=2356 Mon, 13 May 2019 17:08:42 +0000 Rob]]> https://irse.signalpost.org/showthread.php?tid=2356
https://en.wikipedia.org/w/index.php?tit...=894294214 states that "Eurobalises are typically placed in pairs" and that "Singular balises exist only when linked to a previous balise group or when their function is reduced to provide only the exact position."

A single balise is still referred to as a balise group. 

Reasons to have more than one balise in a balise group include:

• Directionality - when a train's onboard unit (OBU) passes over a balise group containing more than one balise it can immediately infer if it is travelling in the normal or reverse direction relative to the balise group and can therefore decide whether the information in the telegram's packets (its data) applies or not.
  
• Redundancy - telegrams can be duplicated in separate balises reducing the chance a failure results in the train not receiving the intended information.
  
• Higher data capacity - a single balise can only contain a certain number of bits of data, more balises (up to 8) may be used to transfer all the required data to the train.
  

However, as far as I can tell, in many situations in a level 2 system a single balise would suffice. Balise linking allows  the OBU to be told of balises it can expect to be read beyond its current position. This linking information allows the train to deduce its direction in relation to a single balise based on a history of at least one other balise group (that may also only contain a single balise). So as long as the OBU has passed over two linked singular balises it knows its direction. In level 2 balises normally contain little information - mainly allowing the train to understand and report its position in relation to a fixed location on the track (the balise).

Cases where more than one balise may still be required (ignoring redundancy and data capacity):

• Where trains enter the ETCS area (hitting the first balise and needing to know their direction) or wake up
  Including exits from sidings, depots and maybe terminus platforms etc
  
• Maybe balises placed to trip trains in 'staff responsible' mode e.g. at the end of authority at a junction. (presumably this function would still work on a singular balise - but only if the train has the linking information).
  

So in a level 2 system the majority of balise groups could have only a single balise? What have I missed; why are balises 'typically placed in pairs'?

(Asking for general knowledge rather than directly for the exam - not sure if this is the best place to post this question)]]>
https://en.wikipedia.org/w/index.php?tit...=894294214 states that "Eurobalises are typically placed in pairs" and that "Singular balises exist only when linked to a previous balise group or when their function is reduced to provide only the exact position."

A single balise is still referred to as a balise group. 

Reasons to have more than one balise in a balise group include:

• Directionality - when a train's onboard unit (OBU) passes over a balise group containing more than one balise it can immediately infer if it is travelling in the normal or reverse direction relative to the balise group and can therefore decide whether the information in the telegram's packets (its data) applies or not.
  
• Redundancy - telegrams can be duplicated in separate balises reducing the chance a failure results in the train not receiving the intended information.
  
• Higher data capacity - a single balise can only contain a certain number of bits of data, more balises (up to 8) may be used to transfer all the required data to the train.
  

However, as far as I can tell, in many situations in a level 2 system a single balise would suffice. Balise linking allows  the OBU to be told of balises it can expect to be read beyond its current position. This linking information allows the train to deduce its direction in relation to a single balise based on a history of at least one other balise group (that may also only contain a single balise). So as long as the OBU has passed over two linked singular balises it knows its direction. In level 2 balises normally contain little information - mainly allowing the train to understand and report its position in relation to a fixed location on the track (the balise).

Cases where more than one balise may still be required (ignoring redundancy and data capacity):

• Where trains enter the ETCS area (hitting the first balise and needing to know their direction) or wake up
  Including exits from sidings, depots and maybe terminus platforms etc
  
• Maybe balises placed to trip trains in 'staff responsible' mode e.g. at the end of authority at a junction. (presumably this function would still work on a singular balise - but only if the train has the linking information).
  

So in a level 2 system the majority of balise groups could have only a single balise? What have I missed; why are balises 'typically placed in pairs'?

(Asking for general knowledge rather than directly for the exam - not sure if this is the best place to post this question)]]> https://irse.signalpost.org/showthread.php?tid=2341 Sun, 14 Oct 2018 12:06:13 +0000 steak]]> https://irse.signalpost.org/showthread.php?tid=2341 I will probably have a revisit.

Thanks[attachment=2353]]]> I will probably have a revisit.

Thanks[attachment=2353]]]> https://irse.signalpost.org/showthread.php?tid=2250 Sun, 10 Dec 2017 08:38:03 +0000 PJW]]> https://irse.signalpost.org/showthread.php?tid=2250 https://irse.signalpost.org/showthread.php?tid=2067 Thu, 17 Mar 2016 12:37:00 +0000 soylemezv]]> https://irse.signalpost.org/showthread.php?tid=2067 Hello everyone;


There are some questions about CBTC.Firstly;What is the difference between Degraded Mode and Fall-Back mode.Secondly, Which conditions Fall-back system is required for CBTC?In long-term, How does Fall-back or secondry control system affect costs? Especially in terms of availability, Is there any positive effect?]]> Hello everyone;


There are some questions about CBTC.Firstly;What is the difference between Degraded Mode and Fall-Back mode.Secondly, Which conditions Fall-back system is required for CBTC?In long-term, How does Fall-back or secondry control system affect costs? Especially in terms of availability, Is there any positive effect?]]> https://irse.signalpost.org/showthread.php?tid=1036 Tue, 29 May 2012 10:54:01 +0000 ricky]]> https://irse.signalpost.org/showthread.php?tid=1036
I have had a go at 2010 Q6 and would like some feedback. I'm a little unsure of the first part and could have probably done with a couple more points for the second part. I assume that for 10 marks they were hoping for 5 risks and 5 mitigations.

I know that at just short of 2 pages it is a little thin on the ground but I'm unsure of what I have missed.

Any feedback would be welcome.

Thanks

Rich

P.S. there doesn't seem to be much forum activity lately is everyone enjoying this little heat wave or is there always a lull this time of year?]]>
I have had a go at 2010 Q6 and would like some feedback. I'm a little unsure of the first part and could have probably done with a couple more points for the second part. I assume that for 10 marks they were hoping for 5 risks and 5 mitigations.

I know that at just short of 2 pages it is a little thin on the ground but I'm unsure of what I have missed.

Any feedback would be welcome.

Thanks

Rich

P.S. there doesn't seem to be much forum activity lately is everyone enjoying this little heat wave or is there always a lull this time of year?]]> https://irse.signalpost.org/showthread.php?tid=898 Sun, 28 Aug 2011 17:06:43 +0000 PJW]]> https://irse.signalpost.org/showthread.php?tid=898 A railway administration is considering the introduction of a moving block signalling system onto their high-capacity two-track suburban railway, which currently has a fixed block signalling system with colour light signals.
The train service will be in excess of 24 trains per hour in each direction and the line features a number of intermediate stations.
Describe the main features of a moving block signalling system. Include in your description details of the advantages and disadvantages of a moving block system when compared to a conventional fixed block system. [15 marks]
What are the problems faced when implementing a transmission based signalling system on an existing trackside signal based infrastructure and how can these be overcome? [5 marks]

I was sent privately an attempt at this question; it did strike me as one I would not have expected this person to have attempted from what I know of their experience.  However it did display some relevant knowledge on the subject and also made a clear attempt to answer the question, but I didn't feel that it had succeeded very well.  

I felt I needed to explain what I'd have thought it should have included, but to do this I needed to effectively do it myself.  Therefore I made an attempt (not time constrained other than I have a 101 things to do and didn't want to waste ages on it).  Having done so I thought I might as well post here; it is probably some 50% more than you could expect to write in examination conditions.]]> A railway administration is considering the introduction of a moving block signalling system onto their high-capacity two-track suburban railway, which currently has a fixed block signalling system with colour light signals.
The train service will be in excess of 24 trains per hour in each direction and the line features a number of intermediate stations.
Describe the main features of a moving block signalling system. Include in your description details of the advantages and disadvantages of a moving block system when compared to a conventional fixed block system. [15 marks]
What are the problems faced when implementing a transmission based signalling system on an existing trackside signal based infrastructure and how can these be overcome? [5 marks]

I was sent privately an attempt at this question; it did strike me as one I would not have expected this person to have attempted from what I know of their experience.  However it did display some relevant knowledge on the subject and also made a clear attempt to answer the question, but I didn't feel that it had succeeded very well.  

I felt I needed to explain what I'd have thought it should have included, but to do this I needed to effectively do it myself.  Therefore I made an attempt (not time constrained other than I have a 101 things to do and didn't want to waste ages on it).  Having done so I thought I might as well post here; it is probably some 50% more than you could expect to write in examination conditions.]]>