Great Western Coffee Shop

From the Rail Accident Investigation Branch (RAIB) website:

RAIB has today released its safety digest (https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/614142/D082017_170518_Chipping-Sodbury-Tunnel.pdf) into trains striking a location cabinet door in Chipping Sodbury Tunnel, 20 February 2017.

The press releases were out a few days ago

I know they were - I received them, at the time (18 May 2017, at 10:00am).  ::)

However, as I was rather busy elsewhere, and I post any such items here on the Coffee Shop forum in my spare time, I chose to post those details here 'whenever I next get a few moments'.

Any member of the Coffee Shop forum who also receives such items of news is very welcome to post details here, for the information and benefit of all of our readers.

 :-X

Hear hear.

It's very interesting to look at who posts the most, and who starts topics the most - those topic starter very often being people sharing news ... that's so welcome in that it helps keep the forum widely informed and vibrant.   Anyone (including guests) can the most prolific members and work out their ratios - between 13% and 18% of posts may be thread-starters and that's a number that I'm very comfortable with indeed.  A big "thank you" to people who fall in that bracket.

Where other members are asking questions within a thread, or discussing wisdom already shared but feel nervous of starting threads, much lower numbers are perfectly fine. Any member can work out their own rates by looking in the statistics on their profile.

I'm going to suggest - for discussion - that members who have posted thousands of messages but less than 4% of them are topic starters should ask themselves "could I help ChrisfN, and Graham, and others who put so much of their spare time into seeding these boards with interesting stories?"

Go on - take a look at your stats and see what your number is!

I only made my post as you stated that the report was released 'today' when it was a few dats earlier.

A possibly-stupid question: why are these things called "location" cabinets?

I have understood them to be "on location" - i.e. near the equipment that they control - rather than being back in the signal box. 

You can have lots of wires from the signal (or track circuit, axle counter, etc) back to the location cabinet, but then just one wire [pair] back to the distant signal box, where the signal widens out into a lot of complex wiring.   We do rather the same thing in IT, where you have complex server but then that reduces down to a very simple thing connection to what might be a thick application / client.  It's why stuff gets compressed into .zips or images into .jpgs which are a lot lighter than one byte / unit of colour per pixel.

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Here's a diagram of how this works.


The head on the top represents the signaller / controller - the unit behind the co-ordination of the whole thing.

That connects via quite a thin connection to a box of tricks in the largely black container. That's the signal box.

Another thinner section for the wiring out to the location cabinet, which is the largely hot pink box of tricks on this diagram, and in this example is controlling two pieces of trackside equipment connected in from below.

Two appendages come out from the signal box. One can be used to join to the next signal box logic (you can see the connector on the end) and the other is a roving engineer based at the signal box - his reach is long enough to get into either of the two boxes (the black one and the pink one) and do things there, but special measures have to be taken if he's working trackside at the very bottom of the diagram ...

 :D In my 50 years in the S&T industry thats the best explanation I've ever seen of how a signalling system works  :D ;)