Swansea & Mumbles Query

[Andy Kirkham]

In this picture, does anyone know waht is the purpose of those centre rails?

 

 

[Michael Edge]

Return current?

[Fat Controller]

5 minutes ago, Michael Edge said:

Return current?

I did wonder about that, as the line was quite often covered by blown sand, which could have caused return via the rails to be less than reliable. 

[Paul H Vigor]

"These centre rails were simply bonded to the running tracks, providing a circuit which could be used to detect whether single line sections were occupied. When a train was occupying a section of single line it completed a circuit which set the line signals to danger."

 

https://variably.uk/2019/06/28/the-swansea-mumbles-railway/

[RailWest]

An interesting site about the Mumbles railway and some nice photos, but sadly riddled with inaccuracies, such as describing the L&NWR line as Great Western etc. Unfortunately there appears to be no way to contact the author to offer corrections.  The block signals themselves were triggered by contacts on the overhead wire operated by the pantograph of a passing train, so I don't see how the 'double rails' would be involved in that process. 

Edited August 4, 2021 by RailWest

[Paul H Vigor]

1 hour ago, RailWest said:

An interesting site about the Mumbles railway and some nice photos, but sadly riddled with inaccuracies, such as describing the L&NWR line as Great Western etc. Unfortunately there appears to be no way to contact the author to offer corrections.  The block signals themselves were triggered by contacts on the overhead wire operated by the pantograph of a passing train, so I don't see how the 'double rails' would be involved in that process. 

https://collection.sciencemuseumgroup.org.uk/objects/co8006248/mumbles-railway-syx-automatic-block-signal-system-for-single-lines-typescript

[The Stationmaster]

19 hours ago, RailWest said:

An interesting site about the Mumbles railway and some nice photos, but sadly riddled with inaccuracies, such as describing the L&NWR line as Great Western etc. Unfortunately there appears to be no way to contact the author to offer corrections.  The block signals themselves were triggered by contacts on the overhead wire operated by the pantograph of a passing train, so I don't see how the 'double rails' would be involved in that process. 

Apart from his inaccuracies he's also into larceny when it comes to photos.  It is either an amazing coincidence or he has helped himself to my scan of a postcard in my collection.  On the other hand maybe the one he scanned not only has exactly the same colour and tonal variations etc as my card but also has precisely the same creases in exactly the same positions on the face of the card.  The card is of course years out of copyright but helping yourself to some one else's scans without showing the source is probably even worse than not bothering to know the difference between the LNWR/LMS and the GWR

[Edwardian]

3 minutes ago, The Stationmaster said:

The card is of course years out of copyright but helping yourself to some one else's scans without showing the source is probably even worse than not bothering to know the difference between the LNWR/LMS and the GWR

 

That's a close one, I'd say.

 

Having done several Mumble pub crawls, I've always liked the idea of quaint saddle tanks hauling double-decked tram cars.

[The Stationmaster]

59 minutes ago, Edwardian said:

 

That's a close one, I'd say.

 

Having done several Mumble pub crawls, I've always liked the idea of quaint saddle tanks hauling double-decked tram cars.

Here you go then

 

 

Mind you I've always rather liked this one , complete with condensing gear (and as pinched for that website)

 

[Re6/6]

I remember travelling on it in the 50s when visiting my great aunt in Morriston.

[Wickham Green too]

2 hours ago, Edwardian said:

.... Having done several Mumble pub crawls, ..........

My speech gets a bit like that after a few, an' all !

[RailWest]

One bit of 'the Mumbles railway' which seems to get little coverage was the old mineral branch up the Clyne Valley. I can recall spending several hours exploring part of the route many years ago. 

 

AFAIK there was no direct link between the Mumbles line and the L&NWR line where the latter passed over the former, but it is possible that both may have served the same colliery and had a connection through the relevant sidings. I don't believe the Clyne line survived as late as the electrification.

[Ian Morgan]

We started on the Mumbles Run when I was at university there, but we soon got fed up of Allbright and went off in search of some proper beer instead (probably Brains SA at the Vivian Arms).

 

@The Stationmaster I see the photos on the variably website are now showing 'credits', your photo being credited as RMWEB.

 

 

[Nearholmer]

PHV

 

That link doesnt seem to go to a viewable copy; can you actually see it and read it?

 

I'm interested, because my first instinct was that the extra rails were "negative reinforcement", i.e. old rails bonded into the return circuit to reduce resistance, which is commonly done on single-line railways because with just two running rails its difficult to keep the resistance within acceptable bounds, but they might not be.

 

KGP

[Paul H Vigor]

1 minute ago, Nearholmer said:

PHV

 

That link doesnt seem to go to a viewable copy; can you actually see it and read it?

 

I'm interested, because my first instinct was that the extra rails were "negative reinforcement", i.e. old rails bonded into the return circuit to reduce resistance, which is commonly done on single-line railways because with just two running rails its difficult to keep the resistance within acceptable bounds, but they might not be.

 

KGP

Yes, the link pops up when clicked upon! They must serve some useful purpose!?

[Paul H Vigor]

2 hours ago, Ian Morgan said:

We started on the Mumbles Run when I was at university there, but we soon got fed up of Allbright and went off in search of some proper beer instead (probably Brains SA at the Vivian Arms).

 

@The Stationmaster I see the photos on the variably website are now showing 'credits', your photo being credited as RMWEB.

 

 

When I was an under-grad the challenge was the 'Topsham Ten'! 

[Nearholmer]

all i get is a tantalising catalogue entry, telling me that it is ten tatty old bits of paper, not a view of those ten bits of paper.

[Ian Morgan]

16 minutes ago, Paul H Vigor said:

When I was an under-grad the challenge was the 'Topsham Ten'! 

 

I seem to remember the Mumbles Run was 18 pubs, but it was a long, long time ago....

[Paul H Vigor]

37 minutes ago, Ian Morgan said:

 

I seem to remember the Mumbles Run was 18 pubs, but it was a long, long time ago....

Prior to the lockdowns I believe there were less than 18 pubs left?

[Engineer]

"... my first instinct was that the extra rails were "negative reinforcement", i.e. old rails bonded into the return circuit to reduce resistance, which is commonly done on single-line railways because with just two running rails its difficult to keep the resistance within acceptable bounds, but they might not be."

 

I'm with you, also by instinct.  Alas, the references to tram and trolley technology I seek haven't yet turned up, plus I'd like to be confident on the location of traction supply inputs to the railway.

 

However, I think the answer is a bit of both - electrical returns and resistance, and signalling, with the factor of a marine environment also relevant.  Looking at the all the images of the Sw&M route I can find, the paired centre rails, seemingly non-contact, are laid in the single line sections only.  Close views of the track are scarce, so can't see evidence of running rail to centre pair bonding, but also no good evidence of 'longitudinal' bonding at joints.  Best images so far: 

https://www.flickr.com/photos/taffytank/albums/72157625334161862

[album]

 https://dewi.ca/trains/swansea/pres0006.html

https://mikemorant.smugmug.com/Recent-uploads-and-queries/Recent-uploads-road-transport/i-4jp2JxJ/A

https://transportsofdelight.smugmug.com/RAILWAYS/RALWAYS-EXCLUDED-FROM-THE-1923-GROUPING/SWANSEA-MUMBLES-TRAMWAY/i-BRjrxBx

https://www.flickr.com/photos/55877117@N05/7809703830/in/album-72157630691827628/

[several images in albums above]

 

http://1.bp.blogspot.com/-qrytXJXvxeM/VINc4gvYPlI/AAAAAAAAA14/eFCL7SDLpfs/s1600/mr11.jpg

See also the linked films below including views from cab en route.

 

Tentative speculation is required.

We know that there is a signalling system for the single line sections which are long enough to be unworkable on line-of-sight.  On tramway lines, if signals were provided, they are likely to be worked from the passing or presence of a vehicle.  Such systems will require information to pass from the 'striking-in' end of the section to the protection signal at the far end of the section [and another bit of information to clear the section once the vehicle leaves it].  The technical solution for tramways could use contacts in the overhead wire with a separate signal wire between the section ends, or it could use a more primitive system that detects the continuous presence of a current return via a tram in the section, which could be detected at either end.  This would be dependent on a good return path and a good end-to-end circuit, plus good pole and wheel-rail contact.  It just could be that the Sw&M used such a simple solution.

 

Continuing to search for contemporary technical information.  Another 'low-tech' tramway that used single-line signalling was the Kinver Light Railway - references yet to surface.  A more sophisticated solution was used by the Belgian SNCV interurban network - reference in French and lacking circuits,https://fr.wikipedia.org/wiki/Signalisation_SNCV_pour_voie_unique

 

https://jonroma.net/media/signaling/railway-signaling/1911/Contact Signals for Electric Railways.pdf

The paper above has turned up and while it gives no answers it is sort-of relevant to the technology for single line signalling.  There is a bonus interest for me in that the author is a Mr Nachod.  That name is linked to the US company that provided all sorts of rail and signal technology including impulse recorders for measuring performance of trolley and tram lines - used on the London tramways and also used as the "See how they run" clocks on the Underground at Piccadilly Circus and St James's Park.

 

Further reference added on the Nachod single-line signalling solution for electric trolley lines, which might be an interesting contrast when we discover the details of the Sykes system used by Sw&M.   Nachod [possibly as a sales pitch] is helpful by including circuits, and the basic principle is to use quite complex contacts attached to the overhead wire at section ends.  Control is over two separate wires linking the electromechanical equipment at each end of the section and there is a ground return required for these circuits, too.  The solution also appears to have permissive features and includes the sophistication of a vehicle counting-in/counting-out mechanism.  These features might have been useful on an interurban tramway such as Sw&M with occasions of very dense multi-vehicle traffic.

https://www.jonroma.net/media/signaling/railway-signaling/1911/Automatic Block Signal System for Electric Railways.pdf

 

 

General interest video of railway at time of closure:

https://www.youtube.com/watch?v=FU9Cq-v9dvA

Swansea Museum talk:

https://www.youtube.com/watch?v=BK9UXq26lLk

Huntley clips

 

Welsh Railway Research Circle page on Sw&M:

https://www.wrrc.org.uk/s&mrrc.php

Article on history and line remains:

http://philtpics.blogspot.com/2014/11/whats-left-of-mumbles-railway.html

 

 

Edited August 8, 2021 by Engineer
Additional image, video and technical references added and adjusted use of English

[RailWest]

The block signalling on the Mumbles was 'tiggered' by contacts off the overhead wired depressed by the pantograph of a passing train. It was a requirement of the system that it did not require a separate power supply and did not draw current continuously from the traction supply. There was a long article about this by (IIRC) John Wagstaff in an early edition of the Signalling Record (I'll try and find my copy idc).

[RailWest]

The article by John Wagstaff was in Signalling Record No 57, tho' sadly my copy doesn't give the actual date.

 

He does make reference to the 'double rails', saying merely that these were electrically bonded to the running rails to 'reinforce' the return circuit, but not making any comment as to whether that was related to the signalling circuit in any way. I have re-read also my copy of the Oakwood Press history of the railway, but that appears to make no mention of the double-rails at all, even though they appear in several of the photographs.

 

In the absence of any relevant photos, it does appear that these double-rails only existed at the start/end of a single-line section. Although the feed for the signalling system come from the overhead wire, I would assume that the return went straight to the traction return 'on the ground', so there would not have been any need to augment the traction return path through the train wheels.

 

Trains leaving a single-line section activated a contactor after entering the start of the loop ahead, and then activated the contactor for the next section ahead before leaving the far end of the loop, so in neither case would a train (at least, certainly a single car) have been over a section of double-rails when doing so anyway.

 

Might the double-rails actually have been some form of mechanical strengthening of the track for some purpose?

[Nearholmer]

Since saying that my first instinct is that they were negative reinforcement, and now learning that they extended only a short distance, a question has struck me: why two?

 

If my mental maths is correct, a greater reduction in resistance would result from stringing one reinforcing rail out over twice the distance*. So why two?

 

Two, close together, hints at a contact below the car completing a circuit between them. If so, could it have been used to initiate operation of the loop points? Or, were they sprung? Or, initiated by motoring current in the OHW, as on some street tramways?

 

* Assume resistance of a single rail, extending twice the distance of those "extra" rails installed =1. With two running rails bonded to one reinfocing rail over that distance, net resistance = 1/3 or 3/9. Now, put two reinforcing rails over half the distance, net resistance = (1/2+1/4)/2 = 3/8.

[Engineer]

"...operation of the loop points? "

 

Image below shows good detail of part of a set of points at Oystermouth, presumed at the Swansea end of the loop.  Also visible in the background is one of the single line signal location cabinets.  Noticeable in the detail is a feature which may be a depression bar.  Final side comment - the photographer's later career was as a very senior railway Engineer.

https://www.flickr.com/photos/taffytank/4392466678/in/photostream/

For reference I've added the album of images to the collection of video and other items that's in a previous post.

Edited August 8, 2021 by Engineer
Use of English

[RailWest]

To pick up on various points raised:-

 

1. According to Wagstaff (who had discussions with Lascelles, the Sykes engineer who designed it) the automatic block signalling system had its own line wires (4?) through the section.

 

2. The points were sprung-loaded and biased to the left-hand road.

 

3. The points were locked by a form of FPL bolt. The mechanical depression bar at the loop exit was depressed by a departing train to remove the FPL bolt and hence allow the train to trail the points against their spring.

 

4. The 'location cabinet' shown in the photo housed the block signal (the large aperture visible to departing trains) and also (in later versions) on the reverse side the 2-aspect signal which indicated to approaching trains whether the points were correctly bolted for the LH road or not.

 

5. It is interesting to note in the latest photo that this appears to be a location at the approach to a loop where there was NO set of double-rails in the 4-foot :-)