Cotswold Line redoubling: 2008 - 2011

[whole diary]

[IndustryInsider]

The block signal on the down line is therefore the signal at Evesham. I don't understand why there isn't a second signal just prior to entering the single line on the down side. This would allow more efficient use of the final section of re-doubled line. In fact is there a need for the signal at the station at Evesham rather than have one on the entrance to the single line?

The only reason I can think of is that it's not the best idea to regularly dispatch trains from a station on a single yellow aspect with the possibility of a SOY-SPAD^▸ (Signal Passed At Danger) (Start On Yellow Signal Passed At Danger).  I can't find anything specific referring to it within the regulations, but it's quite possible that rules ensure that the new signalling systems have to mitigate against the risk of a SOY-SPAD when that signal is protecting a high speed junction.

[Andy W]

The only reason I can think of is that it's not the best idea to regularly dispatch trains from a station on a single yellow aspect with the possibility of a SOY-SPAD^▸ (Signal Passed At Danger) (Start On Yellow Signal Passed At Danger).  I can't find anything specific referring to it within the regulations, but it's quite possible that rules ensure that the new signalling systems have to mitigate against the risk of a SOY-SPAD when that signal is protecting a high speed junction.

Hi II, interesting but do they need a signal at the station or would one suffice closer to the junction it is protecting? For example there are no signals at Pershore so I presume they are not mandatory at stations.

Edited to make sense (I hope)

[IndustryInsider]

If there wasn't a signal at the station then again a train would often depart having received a single yellow before the station, so that would still present a risk should the driver open up full power having fogotten.  The risk of a SPAD^▸ (Signal Passed At Danger) is small of course with TPWS^▸ (Train Protection and Warning System) now able to solve most problems, but even a TPWS activation is taken reasonably seriously.  As I said, I don't know if that's the reason, but it's the only one I can readily think of - and given the much stricter rules for new installations I could see it being the case.

[Andy W]

If there wasn't a signal at the station then again a train would often depart having received a single yellow before the station, so that would still present a risk should the driver open up full power having fogotten.  The risk of a SPAD^▸ (Signal Passed At Danger) is small of course with TPWS^▸ (Train Protection and Warning System) now able to solve most problems, but even a TPWS activation is taken reasonably seriously.  As I said, I don't know if that's the reason, but it's the only one I can readily think of - and given the much stricter rules for new installations I could see it being the case.

Oh II, sorry for being thick - I wasn't thinking of the yellow before the station. As you say a SPAD is rare but certainly should be avoided - particularly if there is the potential of another train coming the other way!!!!

[Don]

The risk of a SPAD^▸ (Signal Passed At Danger) is small of course with TPWS^▸ (Train Protection and Warning System) now able to solve most problems, but even a TPWS activation is taken reasonably seriously.

TPWS activation is a SPAD, as the TPWS grid is parallel to the signal, and only activates (and stops the train) as the train passes the red signal.

The risk of a SPAD is therefore very real, but because all signals are positioned with an emergency empty piece of track beyond them (**), a train can SPAD and be halted by TPWS before entering something like a single line.

Meanwhile every SPAD or SPAD & TPWS activation causes the driver and often signaller to be immediately removed from working (pending drug/alcohol test results), the incident is investigated and the record noted in the driver and signallers files.  A very few incidents like this would end that persons career.

In addition, a record of the signal is made, as part of the ongoing assessment into signals that have multiple SPADs and what should be done to cure them.


(**) called the overlap (TCB^▸ (Track Circuit Block)), or clearing point (ABS or Token/Tokenless block)

[IndustryInsider]

The risk of a SPAD^▸ (Signal Passed At Danger) is small of course with TPWS^▸ (Train Protection and Warning System) now able to solve most problems, but even a TPWS activation is taken reasonably seriously.

TPWS activation is a SPAD, as the TPWS grid is parallel to the signal, and only activates (and stops the train) as the train passes the red signal.

There are two distinct elements to TPWS (three if a signal is fitted with TPWS+).  TPWS activations can (and usually do) happen at the overspeed sensors rather than the sensor actually at the signal.  In most cases, that then stops the train before an actual SPAD has occurred, hence my original post.  Indeed trains are often stopped before the AWS^▸ (Automatic Warning System) magnet for the signal so quite a way short.

[Adrian the Rock]

Hi Adrian, thanks for your input. Out of interest where exactly is the track circuit (ZDS) located?

Just on the short section through the junction points.

The block signal on the down line is therefore the signal at Evesham. I don't understand why there isn't a second signal just prior to entering the single line on the down side. This would allow more efficient use of the final section of re-doubled line. In fact is there a need for the signal at the station at Evesham rather than have one on the entrance to the single line?

Not sure myself.  I think I saw one version of the plan where the down signal was just an overlap distance before the junction, with its repeater shortly before Evesham station.  It's possible the risk of passing the latter at Y was considered, or the disadvantage of trains starting off then having to wait unknown amounts of time when they reached the signal.  Another possibility may have been the risk of confusion given the siting of the other signal that allows reversing moves from the up platform at Evesham, ie of the driver of a train on the down line mistakenly believing that that was 'his' signal when it had actually been cleared for a train in the up platform.

Nor do I understand why there is a signal on the up side just prior to entering the double section as this surely must be set correctly before a train enters the single line at Norton. I'm sure there's a reason - just can't fathom it out.

The signal at Norton Jn gives the train a movement authority as far as the signal just before the junction at Evesham.  Without the latter signal, the line would also have to be clear right through Evesham station.  As it is, a train can leave NJ while the one in front is still in the Evesham up platform.  The current signalling also allows the single line to be used for reversing moves at the NJ end - if Worcester Parkway ever happens that may become a not-uncommon move.  Obviously you don't need the line clear any further than the signal West of Evesham when doing that!

[Chris from Nailsea]

Thanks, Adrian! 

[Andy W]

The signal at Norton Jn gives the train a movement authority as far as the signal just before the junction at Evesham.  Without the latter signal, the line would also have to be clear right through Evesham station.  As it is, a train can leave NJ while the one in front is still in the Evesham up platform.  The current signalling also allows the single line to be used for reversing moves at the NJ end - if Worcester Parkway ever happens that may become a not-uncommon move.  Obviously you don't need the line clear any further than the signal West of Evesham when doing that!

Again many thanks Adrian for your input. I now see why there needs to be a signal prior to Evesham - buy why on the single line & not, say, at the Evesham signal box on the double line?
As it stands if one of our 'not so reliable' 180s breaks down on the up side at Evesham  then a train could still be allowed on to the single line in the up direction & be held at that signal thereby blocking any down line traffic.
I would hope any project to go ahead with the Worcester Parkway station would include re-doubling Norton - Evesham - but then again I live in hope (a small village outside Pershore  )

[eightf48544]

If there wasn't a signal at the station then again a train would often depart having received a single yellow before the station, so that would still present a risk should the driver open up full power having fogotten.  The risk of a SPAD^▸ (Signal Passed At Danger) is small of course with TPWS^▸ (Train Protection and Warning System) now able to solve most problems, but even a TPWS activation is taken reasonably seriously.  As I said, I don't know if that's the reason, but it's the only one I can readily think of - and given the much stricter rules for new installations I could see it being the case.

That was exactly the situation at Cowden which led to the head-on crash. The repeater was before Ashurst station at which the train stopped and the siganl protecting the single line was after.

I am a great believer in the logical siting of signals and not just based on theoredtical stopping distances etc.

The end of platforms seems a very logical place to me. It also has the advantage that it can be used to stop a non stop train in the event of an emergency so that the pasengers can alight if necessary.

I see no reason why if you cannot have two consecutative single yellows if an an intermeadite  signal is required between the full braking distance distant signal and the stop signal. TPWS would presumably lock down the speed at which the driver approached the red. DB^» (Deutsche Bahn - German State Railway - about) get over short spaced signals by having a white light on teh distant indicating short braking distance.

I also like approach control for important junctions although TPWS does in effect act as a form of approach control.

I also favour the stop signal protecting a junction and particulary the entrance to a single line  being fairly close to the junction. Another problem at Cowdem was that the signal was over 500 yards from the actual junction so once SPAD there was no chance of stopping teh train, althogh if the signalman gets a SPAD warning he could try radioing. A case for an outer home with approach controlled and a junction home in site of of the junction.

Not sure about flashing yellows (danger of misunderstanding as at Colwich) the outer home could flash if the junction signal was going to change.

OK you are going to say cost but whilst we still have linside signals I think it important that they are sited with maximum driver siting distance and in logical places in relation to linside features such as brides stations junctions and not nessecessarily just the exact braking distance apart.

The down main out of Padd is a classic case of poor siting as shown by the need for banner repeaters  for several siganls. The most important one being Ealing Broadway where the siganl is 100 yards from the end of the platform 1 and obscured by the overbridge. A classic case of where the signal should be at the end of the platform.

[CLPGMS]

I think that today provides a good example of why a signal is needed in the up direction on the single track just west of Evesham - a fatality this morning between Worcester Shrub Hill and Norton Junction prevented trains from running between Worcester and Evesham.  There is a facility for trains from the Oxford direction to terminate at Evesham and return whence they came.  In order to do this, they have to enter the Evesham/Norton single line.  That signal prevents a train from returning until the points have been correctly set.

Of course, in effect, it replaced a semaphore signal on the single line a bit nearer to Evesham station.

[Worcester_Passenger]

Tragic incident this morning, and our thoughts go out to those involved.

[Worcester_Passenger]

I think that today provides a good example of why a signal is needed in the up direction on the single track just west of Evesham

And the result is:

08:22 London Paddington to Hereford due 11:42
This train will be terminated at Oxford at 09:20.
This train will no longer call at Hanborough, Charlbury, Kingham, Moreton-In-Marsh, Honeybourne, Evesham, Pershore, Worcester Shrub Hill, Worcester Foregate Street, Malvern Link, Great Malvern, Colwall, Ledbury and Hereford.
This is due to a person hit by a train.

[CLPGMS]

In addition to the termination of the 0822 from PAD^» (Paddington (London) - next trains) at Oxford, as I understand it, today's 0648 PAD-GMV terminated at Evesham and returned to form a late running 0904 departure (deputising for the 0826 from WOF), which later terminated at Oxford.

[IndustryInsider]

I'm assuming that special arrangements had to take place in order for that shunt to take place at Evesham as surely there would have been a train in section (the one the person hit) preventing the signal from clearing?