A Tale of Two British Railway Signaling Public Information Films

 The UK is well known for a certain style of public information film that were professionally produced up through the 1980's. A couple go into great detail into the ins and outs of Railway Signaling and served as both a way to increase the public standing of the nationalized railways network in a time of both austerity and modernization and as a recruiting tool to bring new workers with new skills into said modernizing rail industry. 

The first film, entitled Electrical Engineering on the Railway and produced in 1962, falls more on the recruiting side of things as relay based "electric" signaling replaced largely mechanical manual block signaling on the busiest unresignaled main lines of British Rail. While this may been a bit odd as North American signaling has largely discarded purely mechanical signaling by the 1920's, Britain might get a bit of a pass given the toll a pair of World Wars took on its railways and economy.  Point of note include:

• A general lack of safety practices including, but not limited to protective clothing and burn pits for demolished signalboxes.
• The appearance of pneumatic point machines and North American supplied GRA Model 5A electric point machines.
• Rather flimsily looking track circuit bonding wires.
• The continued construction of brand new mechanical lever type interlocking frames.
• Some components of interlocking hardware being hand forged in house.
• A general use of North American pattern glass case plug-in and shelf type relays.
  

The second film, entitled Points and Aspects, was made in 1974 and shows the leap in British signaling from what one might call an updated basic CTC plan to something that was making far more use of computer and telecom technology to enable the so called wire area "Power Box" era of British signaling with as much automation as 1970's technology could muster..  This film is definitely trying to sell the public on British Rail not being a basket case and is worthy of their continued support and patience.  As a result an emphasis is given to the higher tech elements.

What is especially fascinating is that these two videos appear to span the moment when  the UK went from a very North American leaning approach to signaling technology, to a more European approach. Despite very different operating practices, North America and the UK had very closely aligned signaling supply companies with both GRS and US&S licensing UK technology and then supplying their own products back through local subsidiaries like Westinghouse. In the 1970's we are seeing the end of the glass case relays and Model 5 and M3 point machine that stared in the 1962 film.

GRESHAM JCT's Sequence Switches Explained

 Years ago I wrote up a profile of METRA's GRESHAM JUNCTION tower on the Rock Island division south of Chicago.  Not only had GRESHAM JUNCTION managed to stay open into the 21st Century, it was a unique North American example of a sequence switch interlocking. Supplied by the Standard Telephone and Cables Company of London, the interlocking used telecom grade sequence switches to carry out the interlocking functions instead of relays.

In my original post I provide photos of the equipment as well as a general concept of how sequence switches work and some sequence switch interlocking circuit diagrams from the UK, but without time and access to the equipment or someone who was intimately knowledgeable about how it functions, my commentary had to remain at a very high level.  Fortunately, the gang from the Connections Museum in Seattle is on the case because sequence switches is pretty much how Bell Number 1 Panel central office machines functioned (again, as opposed to later relay based technologies). I could try to go into things, but fortunately the museum's YouTube channel has video that is specifically about how sequence switches work. 

Once you see them in action at the Connections Museum, their function in the photos from GRESHAM JCT will become obvious. Of particular note is the function of the magnetic clutch mechanism that rotates the switch spindle. Perhaps if I stare at things enough I can determine what each sequence switch corresponds to in the interlocking.  Is each a complete route? An entrance? An exit? An entrance-exit combination? Let me know in the comments if you figure it out.  BTW, if you like this video take some time to watch the rest of the Museum's content.  It's top notch and does a superb job of explaining some normally opaque topics in the realm of pre-modern telephone switching technology.

UK Lickey Incline Classic Signaling

I found an interesting video on the manual block setup on Lickey Incline, the steepest Main Line gradient on the UK.  This 2.65% grade stretched over two miles on the line to Birmingham and due to the under powered nature of UK locomotives, most trains, passenger included, would need help getting up.  Although the line was fitted with track circuits, manual block was still employed.  To ease operations, an intermediate manual block signal was provided so that two trains could climb the grade at the same time.  This video details how the blocks were worked and how the helpers were dealt with.



Compare with operations on the steepest main line grade in North America, Saluda.

London Underground Edgware Road Signal Cabin

The Londonist has just produced a very interesting piece on the LUL Edgware Road signal cabin, which was built in 1926 with a Westinghouse Style K interlocking machine (license built UK version of a US&S Model 14).  Unfortunately the London Underground has been bitten by the same CTBC bug as the NYC Subway, despite the old adage "If it ain't broke, don't fix it".  The article comes with an attached video and numerous photos of the signal cabin and a number of other cabins also at risk for closure.  Because putting one's eggs in one basket is all the rage, the LUL will also be converting to a centralized control center model.



The good news is that there are plans to preserve the cabin, although the ultimate level of interactivity or public access remains unclear. Here is another video showing a compressed view of an entire night shift at the cabin.

Swindon Power Signalbox Restoration

Hopefully most of you are familiar with the excellent job the crew at HARRIS tower has done reactivating its US&S Model 14 interlocking machine with the help of a lot of PLC's and Train Dispatcher 3.  Well over in the UK a project is afoot  to do the same thing to the old NX panel from the Swindon Power Signal Box.  The "PSB's" were a generation of British area signaling control centers that replaced the most hard pressed mechanical tower in the 1960's and 70's.  They used a lot of relay logic to implement push button N-X operation and many eventually came to feature integrated train description.  A tour of Swindon PSB can be seen below.



Swindon, like many other PSB's, are being removed from service because many of the telecon grade relays that drive the user interface and other ancillary logic are becoming nearly impossible to maintain.  Here below is a video showing the "domino" style panel board being re-assembled after it arrived at its preservation site.



Here is a brief demo of the old panel UI hooked up to some modern electronics.  And yes that is indeed the Danny Scroggins who is so well known for his comprehensive documentation of vintage British signaling and signalboxes.



Of course there is an entire Youtube Channel devoted to the project, with videos like this one showing the progress of the custom PLC components.



In fact the panel has its own preservation society and as of now they are projecting an grand opening date of June, 2018, plenty of time to score that cheap transatlantic airfare.

Videos from Across the Pond

I just found a few interesting videos involving UK signalboxes.  The first two involve the Banbury North Signalbox , which was recently decommissioned, but then opened for public tours (a somewhat rare occurrence due to all the health and safety BS their railways are tied up in).  Unfortunately the signalbox, like many others, is slated for eventual demolition so little other purpose than it being there.  Britain's attitude towards its decommissioned signalboxes is downright baffling seeing as every foot of railway infrastructure is publicly owned and almost everything in the UK is covered by some sort of historic preservation law.  Network Rail also seems to be chronically pressed for cash and where they can find the funds for these demolitions is beyond me.

The first video shows the full tour that was given to the public and the second video shows the view from the locking room as the levers are manipulated.  Those of your from North America should keep in mind that mechanical British signalboxes such as this, typically work on the manual block system.  Some track circuits may be provided, but train movement is primarily by manual block using block instruments instead of voice or message communications.





The third video is from Harrow On The Hill signal cabin on the London Underground in 2002 and shows a Westinghouse Style N machine, which is basically a US&S Model 14 with the levers pivoted around 90 degrees so that they throw in the traditional "back and forth" orientation, instead of left and right.  Even the tri-positionality of some of the signal levers is retained.  The most fascinating thing about this video is the use of a pneumatic assist to move levers at the far end of the frame when certain route levers are pulled in the primary operating area.  It's basically a non-vital intra-tower remote control system that doesn't require additional relay logic, a serious expense in pre and post war Briton.  This technology was later extended to create the Style V frame where all the levers were moved primarily by remote control pneumatics.

BTW, if you are wondering why the model board is all lit it, is it because that was considered safety critical information and any bulb out had to mark the track circuit as "occupied".  Of course with the bulbs burning by default I am sure there would be plenty of bulb out opportunities.

British Power Signal Box Video Tours

On a British signaling forum I frequent, a signaler known as Ian Ives uploaded a number of VHS video tours he made of some London area British Power Signal Boxes (also called Panel Signal Box or PSB) back in the 1990's.  For those of you who don't know, a PSB is roughly equivalent to the type of interlocking tower that was largely passed over in North America in the evolution from single interlocking towers to dispatch offices. They are basically what the NYC Subway calls Master Towers.

Popular in the UK between the 1960's and the 1980's, they replaced most of the electro-mechanical interlocking towers in busy urban areas as well as scores of pure mechanical towers.  PBS's contained large NX style model boards with light green tiles.  Their most high tech feature was automatic train description using small LED or CRT display boxes, which in the 1960's was quite a feat indeed.   While well documented pictorially, there are relatively few video records of how these panels were worked so check out these great resources.

If you like these, make sure you visit and/or subscribe to Ian's channel here.  If you would like an official tutorial on how these panels worked, you can find it here.