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Author Topic: RAIB investigate "serious signalling irregularity at Cardiff" - 29 Dec 16  (Read 2595 times)
bobm
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« on: February 03, 2017, 09:30:23 am »

From the RAIB

Quote
Over the Christmas period in 2016, Network Rail carried out extensive resignalling and track remodelling work in and around Cardiff Central station. This was the final stage of the Cardiff area signalling replacement scheme, a project which has been in progress for several years. This stage involved the closure of the power signal box at Cardiff, with control of the area moving to the South Wales Control Centre (SWCC), and changes to the track layout and signalling on the east side of Cardiff Central station.

Some of the new track layout was brought into use on 29 December. At 08:46 hrs on that morning the driver of train 2T08 from Cardiff Central to Treherbert, which had just left platform 7, noticed that a set of points in the route his train was about to take were not set in the correct position. Train 2T08 was the first up train on the Up Llandaff line after the start of service over the new layout.

The points at which the train stopped were redundant in the new layout and should have been secured in the normal position in readiness for their complete removal at a later date. The project works required eight point ends in two separate locations to be locked and secured in this way. In the event only six of the eight point ends were locked and secured, and the line was re-opened to traffic without the omission having been identified by the project team through the normal checking processes which should take place as part of this type of works. These two point ends were left in a condition in which they were unsecured and not detected by the signalling system, and the points at which train 2T08 stopped, points 817A, were left lying reverse. If the driver had not noticed the position of these points and stopped, the train would have been diverted towards line E (the former down relief line) on which trains can run in either direction. The new signalling system uses axle counters for train detection, and in this situation the system would not have identified that the train was in the wrong place.

A few minutes earlier, at 08:24 hrs, another train, down train 1V02, had travelled over the other points which had been left unsecured at the other end of the same crossover (817B). These points had been left in the normal position, which was correct for trains travelling over them in the down direction.

No-one was injured and no damage was caused by either event, and Network Rail acted quickly to secure both sets of points.

Our investigation will examine:

the events leading up to the commissioning of the new track layout in the area of 817 points
the methods that Network Railís Cardiff area signalling replacement project used for project management and assurance processes
the on-site team briefing and works management process.

It will also examine any relevant management issues and consider previous relevant recommendations made by the RAIB.

Our investigation is independent of any investigation by the railway industry or by the industryís regulator, the Office of Rail and Road.

We will publish our findings, including any recommendations to improve safety, at the conclusion of our investigation. This report will be available on our website.
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eightf48544
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« Reply #1 on: February 03, 2017, 09:51:08 am »

Quote:

"The new signalling system uses axle counters for train detection, and in this situation the system would not have identified that the train was in the wrong place."

Enough said.
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chrisr_75
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« Reply #2 on: February 03, 2017, 09:56:16 am »

I think that's a little unfair 8F, this is surely the most important point (excuse pun), if the points had been properly secured or removed, axle counters would not have entered the equation:

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The points at which the train stopped were redundant in the new layout and should have been secured in the normal position in readiness for their complete removal at a later date
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stuving
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« Reply #3 on: February 03, 2017, 10:38:39 am »

I think that's a little unfair 8F, this is surely the most important point (excuse pun), if the points had been properly secured or removed, axle counters would not have entered the equation:

Quote
The points at which the train stopped were redundant in the new layout and should have been secured in the normal position in readiness for their complete removal at a later date

... and if the points were still in the new layout there would have been axle counters each side of them to provide that detection.

... and furthermore, if track circuits were still in use there, the two track circuits ending at that switch on what is now (to be) plain line would have been joined into one. The status of the non-existent line the train would have taken is unclear - the outcome would have depended on how long it is and where the train stopped.
 
« Last Edit: February 03, 2017, 10:48:15 am by stuving » Logged
eightf48544
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« Reply #4 on: February 03, 2017, 10:58:53 am »

Whether axle counters are relevant or not  it was still a serious incident and lesson must be learned. to ensure that a more serious incident doesn't occur.

Maybe that review should include whether axle counters should be used in junction areas.
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SandTEngineer
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« Reply #5 on: February 03, 2017, 12:46:52 pm »

It was absolutely nothing to do with axle counters.  The S&C was redundant and was not secured out of use correctly.  Even if the layout had still been track circuited the applicable bonding would have been altered to make the points 'disappear' in the new signalling system.  The only correct way to protect against such an incident is to detect the points in the new signalling system and that is not usually done unless the points are to remain in situ after 6 months of decommissioning.  Newly installed 'out of use' points in an old signalling system have the same risk and same rules applied to them but its usually quite easy to detect them in some way so these days its usually, but not always, done at time of installation.

Overall the incident was caused by a procedural error and that is what RAIB will investigate.  Not the first time an incident like this has happened though.

Maybe that review should include whether axle counters should be used in junction areas.
I'm interested to know on what basis you justify a review of the use of axle counters in junction areas?

« Last Edit: February 04, 2017, 07:02:36 pm by SandTEngineer » Logged

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