Railway signals

[Walkingthedog]

Unless you want your front garden dug up and an underground feed laid to your house a pole is the only way so that is why they replace decayed poles with new ones. Really they are the best way to get wires to a house as they can be easily replaced if faulty or added to if you require another line.

Why should it all fail TWD. If the trees are a problem the neighbours will have to do something about it.

[teedoubleudee]

Unless you want your front garden dug up and an underground feed laid to your house a pole is the only way so that is why they replace decayed poles with new ones. Really they are the best way to get wires to a house as they can be easily replaced if faulty or added to if you require another line.

I do understand that but apart from the continuing high maintenance (there is currently a short section of my road (a cul de sac) that for the past few days has traffic light signals and warning boards (one placed in the middle of my drive entrance which I moved!) whilst more repair work is being carried out), they are an awful eye sore. We even have mains voltage poles at the end of the road, but thankfully not to our property. You expect poles if you live in the outback but not in a built up area.

[Walkingthedog]

They are obviously doing a major upgrade TWD. Hardly ever see an engineer up a pole round here just occasionally in a joint box. Usually running fibre cables.

There is a lot of upgrading going on at present with new fibre cables and replacement cabinets, the green boxes.

[Tricky Dicky]

New builds tend to have ducts to houses rather than poles, certainly the case at my daughters house, because it is easy to do as part of the build. The odd thing is that the builder installs the ducting on behalf of Openreach and sometimes you see Openreach contracted to do the ducting but no ducting for cable TV and as far as I know there are no plans to share the existing ducting. As it happens there is no cable TV in their village so not an issue at the moment but what happens if they do get cable are we going to see roads and pavements ripped up for more ducts?

Although the heyday for cable laying has passed since the 90’s you still see the odd bit of new cable being installed. The village next to us took up a Virgin Media offer to presign up customers once a certain number were signed up the cables were laid with roads and pavements ripped up even in parts that already had ducting for Openreach. You would think with broadband now being considered as an essential service alongside other utilities you would think with new builds a bit more forward planning would be used with universally available ducts provided for whichever provider a customer wanted.

Although the broadband market appears competitive with many providers the nuts & bolts of the infrastructure is mainly provided by two monopolies, Openreach and VM and so you really have not much choice. Round here Openreach are installing FTTP under the the Fibre forCities Scheme although most seems around the outskirts of the city which seems perverse. Looking at the map it shows the next village is being done in the coming months but it stops short of where I live by a couple of hundred metres Grrr! There are no plans to extend into our district and I suspect there never will as we are cabled up for VM.

Richard

[brian1951]

Back to the main topic now chaps. before we dig up half the country.

[IanAlan]

Thank you everyone for your helpful replies, especially WTD whose reply was crystal clear and exactly what I was wondering. As it was me that diverted the thread from its original course, I shall try to atone by asking a signal related question, which may be useful to SootyBrum.

I understand that the signals tell the train driver what they should do as they approach a block of track. I can imagine some factors that would cause the engineers to divide a given piece of track into blocks such as turnings (points), stations, bridges, tunnels, steep inclines. In sort, anything that wasn't a continuous run, where the presence of another train could be potentially dangerous. So my question is, what sort of lengths would a block of track be? I imagine that in open countryside it could be many miles, whereas in an urban area much smaller. Are there any other factors that anyone else on MRF would like to share regarding how the track was designed and divided into blocks?

Many thanks again to SootyBrum for raising this interesting topic.

[Brian]

Block sections on the real thing are determined by the line speed and train frequency.

[LC&DR]

Unless you are extremely fortunate and have a large barn into which you can build your model railway you will have much less distance to place signals realistically.

To give some examples it was usual for a distant signal to be 3/4 of a mile before reaching a home signal, and the clearing point beyond the home signal which the signalman had to keep clear before accepting a train was 440 yards. Now at 4mm scale 3/4 mile is 52 feet, and 440 yards in 4mm scale is about 17 feet.

Colour light signals are generally a mile apart give or take a bit, This is about 70 feet in OO! Block sections between signalboxes can be many miles. Most colour light signals had a 200 yard overlap which had to be clear before the signal next in rear can clear before another train could approach. 200 yards is over 8 feet.

So we have to compromise.

As a good rule a stop signal needs to be positioned before any points or crossings so if the way ahead is not clear an approaching train can be stopped. This applies to any route passing over the points in the normal direction of travel. Also where two or more routes are possible for an approaching train there should be a stop signal arranged side by side for each route. Only one signal will be cleared indicating which route the train will take. Colour lights do this somewhat differently, using route or junction indicators.

A stop signal is one which can display a red light and/or has a red painted arm. It can of course display a green light when the way ahead is clear. A distant signal is one which can only display yellow and green lights, and/or a yellow painted arm, and the arm has a fishtail vee cut out of the end.

Where block sections are short and signalboxes are close together the distant signal of one will be placed under the stop signal of the preceding signalbox on the same post. Precautions are taken mechanically to prevent the distant signal being clear until the stop signal above is also clear.

For movements against the normal flow of traffic, e.g. shunting, ground signals are provided to indicate the shunting route is selected, the necessary points are set and it is safe to make the shunt.

Try not to over populate the layout with signals. Think carefully about the moves your trains will make, and erect signals to control the moves safely. Less is more.

[IanAlan]

Thank you Brian and LC&DR. My interest was purely theoretical - I wasn't expecting to model them as a 1/76th replica of the real thing (my layout is a roundy-roundy, which is hardly realistic). You've both answered in a way that will help me to make informed choices about placing signs, so that they look right (or at least not too obviously wrong).