AWS magnet placement

[Gibbo675]

And Shed Test Magnets fixed in the 4-foot on TMD exit roads. Do they ever get provided these days?

We had one at the exit of the ELR at Hopwood ground frame for that very purpose.

[The Stationmaster]

The ramps for the predecessor GWR system were placed at the signal I think.  Perhaps someone thought the driver should observe the signal rather than assuming its position from the indication received?  In any case this would have generally been at semaphore distant signals where there were only two possible aspects and the driver could look back to check. 

 

GWR ramps varied.  Originally they seem to have been 200 yards in rear of the signal but latterly (BR days) a distance of 440yards in rear of the signal is quoted in several offical publications (and 200 yards in rear of colour light signals capable of showing a caution aspect).   However at signals with a lower arm distant the ramp was placed 'at', or very slightly in advance of the, signal for obvious reasons. 

[Rugd1022]

AWS magnets can be anything from 200 yards in rear of a signal to 50 yards in advance of it.

There are signals with them ahead of it at Grantham and Doncaster on the goods lines

 

Before Rugby was resignalled during the WCML upgrades earlier this century there was an AWS ramp about twenty yards ahead of (ie : beyond) RY63 signal on the Up Slow / Northampton line, in the shallow cutting between the GC Birdcage bridge and Clifton Road bridge. Nobody ever explained to us when we were road learning why it placed there!

 

There is still a 'shed test' AWS magnet as you come off Bletchley TMD.

Edited November 24, 2018 by Rugd1022

[DY444]

I don't know if they are still there but Waterloo had AWS magnets adjacent to the platform end signals as did a couple of other places in the Wimbledon panel area (eg. the DS at Wimbledon P8).  I have an idea they were provided as a SPAD mitigation measure in the days before TPWS.

[Edwin_m]

I don't know if they are still there but Waterloo had AWS magnets adjacent to the platform end signals as did a couple of other places in the Wimbledon panel area (eg. the DS at Wimbledon P8).  I have an idea they were provided as a SPAD mitigation measure in the days before TPWS.

That's the most likely reason - SPAD mitigation became a hot topic after accidents such as Purley and Bellgrove.  Ely was another re-signalling that included them. 

[Waverley47708]

Would AWS be used in passing loops used by passenger and freight.    The location and time period ( which I understand is all important  from seeing many questions asked in the past on RMWEB) is the Mid 80s Scotland.

 

 

 

 

Edited October 17, 2019 by Waverley47708

[St. Simon]

57 minutes ago, Waverley47708 said:

Would AWS be used in passing loops used by passenger and freight.    The location and time period ( which I understand is all important  from seeing many questions asked in the past on RMWEB) is the Mid 80s Scotland.

 

Yes

 

Simon

[Edwin_m]

1 hour ago, St. Simon said:

 

Yes

 

Simon

I certainly agree for signaling that was newish at the time - every signal got AWS in the Edinburgh-Fife re-signaling around 1980 for example.  But would this still be true if the line still had semaphore signaling?  Traditionally AWS was only fitted at the distant in these areas.  I suspect high risk stop signals (which would almost certainly include those governing loop exit and possibly entry too) would have got AWS, but probably not until the late 80s in response to the spate of single line collisions.  And possibly fitted as a "SPAD magnet" after the signal Ely style rather than (or as well as) the normal position on the approach to the signal.  

[Mark Saunders]

34 minutes ago, Edwin_m said:

I certainly agree for signaling that was newish at the time - every signal got AWS in the Edinburgh-Fife re-signaling around 1980 for example.  But would this still be true if the line still had semaphore signaling?  Traditionally AWS was only fitted at the distant in these areas.  I suspect high risk stop signals (which would almost certainly include those governing loop exit and possibly entry too) would have got AWS, but probably not until the late 80s in response to the spate of single line collisions.  And possibly fitted as a "SPAD magnet" after the signal Ely style rather than (or as well as) the normal position on the approach to the signal.  

 

AWS installation is based on the time of it was installed and signalling system used!

 

Absolute block only semaphore signalling would only get a magnet at the distant. 

 

Track Circuit Block would get each main aspect signal except in complex areas such large stations.

 

SPAD magnets were a 1990's thing which was developed into SPAD indicators!

 

Risk assessment is a modern thing starting in the 1980's if I recall correctly.

 

York to Scarborough was only fitted with AWS in about 1994.

 

Mark Saunders

[TheSignalEngineer]

As Mark says, dates varied for various styles of fitment, but off the top of my head our general fitment arrangements in that period would be

 

Absolute Block areas

Only at Distant signals and Intermediate Block Distants. 

 

MAS areas

All signals capable of showing a yellow aspect on Passenger running lines and some through Goods lines especially if used for Passenger diversions.

At two aspect R/G signals following a run of three or four-aspect signals on Passenger lines or fitted goods lines.

At the signal acting as the Distant for the signal protecting the junction of an unfitted line with a fitted line.

Between the signal protecting the exit from a Goods Loop and the points connecting it to a fitted through running line. 

 

[Ken.W]

On goods lines the reason for the AWS, if provided, being at or beyond the signal is that they're normally worked by Permissive Block (ie more than one train allowed in section). This was to guard against the possible situation where a train approaching the signal in the dark or especially in heavy fog receiving the bell when the signal's just cleared for a short train or light engine standing at the signal.

 

Test magnets are still provided at depot outlet signals, though now not always normally used. The Rule Book instruction was for the driver test the AWS by allowing it to initiate a brake application before canceling it. Unlike older traction where the AWS reset as soon as canceled, modern stock has a 2 minute time delay to reset a brake application, and this was playing havoc with the timetable at busy time when several trains were booked to leave the depot closely following each other.

Our company instructions now (for around the last 5 year or so) is to cancel the warning without the brake application being made. Provision of the Driver's DOO slip is confirmation the brake application test's been done by depot staff using a hand test magnet.

I did, once receive the bell on a test magnet coming off Heaton with a 143. Stopped, reported it to the signaler, changed ends, and straight back in the depot!

Edited October 21, 2019 by Ken.W