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Technical Specification of Railway Signalling System
#1
Hi,

I have been working on technical specifications. In basically , Which informations should be included in a technical specification for a new  line? I only consider informations that to be written quantitative, such as headway, dwell time, maximum speed , temporary speed restrictions etc. I exclude the interfaces between signal system and other systems.

What can be written about the following topics?(From the railway administrator perspective)

Interlocking
Track circuits&Axle counters
Switches
Signals
Train-wayside communication
ATP and ATO
Reliability,availability,maintainability and safety

Especially ,about the track circuits & axle counters, signals and point machines Can you share with me If you have technical specification? Happy New Year to all! Thanks.
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#2
(29-12-2016, 02:31 PM)soylemezv Wrote: Hi,

I have been working on technical specifications. In basically , Which informations should be included in a technical specification for a new  line? I only consider informations that to be written quantitative, such as headway, dwell time, maximum speed , temporary speed restrictions etc. I exclude the interfaces between signal system and other systems.

What can be written about the following topics?(From the railway administrator perspective)

Interlocking
Track circuits&Axle counters
Switches
Signals
Train-wayside communication
ATP and ATO
Reliability,availability,maintainability and safety



Especially ,about the track circuits & axle counters, signals and point machines Can you share with me If you have technical specification? Happy New Year to all! Thanks.

I assume that the line has / is being built and the specification is for the signalling system both lineside and on-board. Certainly there will be some interfaces that would need to be considered- the trains, power supply, the stations.  If however the railway is ""green field" then much could potentialy be left to the contractor to deliver in the way they saw fit but in a manner which met a performance specification that also included RAMS, security constraints.
In that case then nothing would be specified about track circuits or axle counters; the contractor might just use train position reports rather than lineside train detection.  However the specification certainly would need to include requirement to be able to recover readily from a failure in which a train had become non-communicating and this might itself drive a certain level of infrastructure based train detection.

If the line is stand-alone, then the railway may not wish to be prescriptive about the style of point machine. but just specify things like the thrust required, the time to throw, the maximum periodicity of routine servicing, the service life etc..  Conversely if this is a new line associated with one already in operation, then there are many maintenance advantages of specifying exactly what point machine is to be provided, in order to get synergy with the existing- lower spares holding,  no need for special training, gauges or tools etc.

There may be no need to specify much about the functionality of trackside to train communication leaving these details to the contractor, but it is likely that the railway may only have a limited radio spectrum available to it within which any system must operate and hence this would be important to include. Similarly if the trains are pre-existing or are being procured separately there would be a host of things to include (space, power, the provision that has been made for mounting aerials and cable routes to them, interface with train braking system etc etc).

The railway may wish to implement some very specific interlocking practices, but on the other hand may not feel the need to do this and at the other extreme just place safety requirements on the complete system.

Hence it is hard to suggest what should be included in a specification other than the general advice of being very clear about what is actually wanted and what constraints there are.  Presumably you have some potential solution in "your mind's eye" which is implied to some extent by your list of topics, but you need to have thought whether you'd be open for a somewhat different one.  Your list included "signals" so presumably you envisage a broadly traditional lineside signalling system and if that is what you want then you should specify, but to the extent needed for the circumstances (you may need to specify the exact physical form of signal, just the meanings of the various indication elements to the driver, or indeed deliberately leave even that undefined and so writing the railway's rule book around the signalling offered rather than defining the signalling to follow an already extant rulebook).

The specification should be the means by which the railway tells the supplier all the things that they need to know to come up with a system that would completely satisfy the client railway (which generally has multiple stakeholders); try to make complete and unambiguous so attempt to leave no room for assumptions. It is all about characterising the environment; in some scenarios distributing data by fibre optic cable right up close to the end equipment might be regarded as good, whereas in a different context it may be better to have a small number of large equipment rooms and then distribute to the trackside equipment by multiple copper tail cables. The supplier cannot know what the railway administration judges is overall the better option unless the specification includes relevant wording.

So no easy answer as the question is rather open ended.  A specification from another railway may well give some pointers and particularly be a prompt to specify certain things that were just being assumed, but I'd caution against making up a specification from combining multiple portions from different projects!
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