Signalling in the UK

[JCitron]

http://youtu.be/qpYkuBvmmak

This is pretty interesting especially for someone like me from across the pond!

John

 

[airtime]

Very good find John, I've seen this a couple of times, and I have found it very interesting, it gives you the basics of UK signalling, some of those signals are quite old now, and are being replaced by the new Dorman signals, However, the principal stays the same for what they mean and how they are used.

Thank you for posting this here, as I usually forget to bookmark it, and never remember where to find it when searching through youtube.

Joe Airtime

 

[Paulsw2]

Very evocative: brings back memories of BR blue in the 1970s/80s.

Paul

 

[JCitron]

This is a very interesting approach to signaling, and it looks way too complicated. It's not that signaling shouldn't have error checking and redundancy built into the process, but there also appears to be a lot of wheels spinning around as the signalman runs around flipping the levers.

For this I can see why the railroads have gone to automated signals over the years. Many of these functions are easily carried out by a computer today, and thus the development of dispatching offices and control boards.

What I found interesting is the general signaling purpose to control direction rather than speed. In the US our signals are for speed, but are also for direction as well. Using the searchlight signals, a red over green, or green over red on a dual head, indicates a diverge clear. This means that one track is blocked and the other is full speed (track speed). A red over yellow, or yellow over red would mean that the diverging route is to be traveled at half speed. Blinking yellow signals indicate an imminent stop, so travel slow enough to prepare for a stop at danger.

John

 

[Paulsw2]

I've always thought of the distant, or yellow colour light signal as an indication to slow the train if it's 'on' (ie. the next signal is at stop). Isn't this a control of speed as well as direction?

Paul

 

[stovepipe]

For this I can see why the railroads have gone to automated signals over the years. Many of these functions are easily carried out by a computer today, and thus the development of dispatching offices and control boards.

John

A semaphore signal box is a mechanical computer in many ways. It's quite amazing when you consider that they were installing 200+ lever boxes well over a 100 years ago. They must have been amongst the most complex machines being made at the time, and each one bespoke. Afterall, it wasn't so long beforehand that Babbage was trying (and failing) to make the first mechanical computer.

 

[bassist118]

Also drivers have to undergo many many hours gaining route knowladge which they have to sign for and prove they know the route before they're alowed to haul freight or passengers, to the point at which (espically in steam days) a driver can tell just from the sound of the wheels on the track and how hard the engine is working they can tell exactly where they are.

Andy

 

[JCitron]

A semaphore signal box is a mechanical computer in many ways. It's quite amazing when you consider that they were installing 200+ lever boxes well over a 100 years ago. They must have been amongst the most complex machines being made at the time, and each one bespoke. Afterall, it wasn't so long beforehand that Babbage was trying (and failing) to make the first mechanical computer.

Wow! I never thought of it that way. A truly hand operated computer. These really are Victorian mechanical marvels that a modern computer pales by comparison. We can say that the signal box and the piano are the two Victorian machines that survived nearly intact into the modern times. The piano was originally developed in 1700, but it took another 160 years to come before being perfected. A piano technician, making a living in 1880, could very easily fix a modern grand piano. Not much has changed in the years in between except for the materials. We use plastic today where the Victorians used wood and felt.

The signal box from Victorian times, didn't really change until nearly 100 years later. Sadly, though a signalman back then would have difficulties repairing the signals and relay equipment we use today because there is so little of the real mechanical parts left. The fact that they remained in operation until fairly recently spells the testament to the quality and reliability of their operation.

John

 

[pfx]

A few still are in operation now along with numerous examples on preserved lines. The one I work at is in the process of re-engineering the signal box and I've been in the ground frame room a number of times and the level of engineering in it is quite astounding.