Pietermaritzburg to Ladysmith Signals

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Hermann Kuhne
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Joined: 03 Feb 2011, 20:38

Pietermaritzburg to Ladysmith Signals

Post by Hermann Kuhne »

I am trying to recreate the line between PMB and Ladsymith for the Railworks Simulator 2013. The idea is to recreate it as best as possible. That includes a 3'6" Cape Gauge line, authentic station buidlings, at least, and a correct signalling system for the route. Question:are all mainline routes signalled like this?
Can't find any info on the signalling system though on the net. Got quite a few good photos though. Seems to be loosely based on the UK system of 4 Aspect Junction signals with directional arms (lighted), and 2, 3 and 4 Aspect Auto and Control signals. Question: why sometimes 2, then 3 and then 4 Aspect signals?
Any help would be appreciated:)
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Steve Appleton
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Re: Pietermaritzburg to Ladysmith Signals

Post by Steve Appleton »

Hermann, I am not directly familiar with the signals on that section, but they would follow the same colour-light signalling rules used across the country.

Indeed, the local colour-light signalling system is similar in concept to the UK system (absolute block-based - signals indicate track occupancy ahead and the routing, but do not dictate speed - unlike Europe and the USA) but the local version has grown some important differences. A complete description is probably beyond a simple description here.

Briefly, most two-aspect signals (note, two aspect does not necessarily mean two lenses - there exists searchlight-type signals which display more than one aspect but using only a single lens - a colour filter is moved), are used as warning signals (roughly equivalent to the semaphore distant signal) which display only the aspects clear (green) and caution (yellow). Those signals are equipped with a rectangular white board with a black diagonal stripe on it. The sole purpose is to provide advance warning of the state of the next stop signal. Another type of two aspect signal (often only one aspect is used) is a repeater signal whose purpose is to show the status of a stop signal that is initially or partly obscured by infrastructure or a curve. These signals are marked with an "X" near the lenses.

Most controlled signals are capable of showing at least three aspects including "danger". These are known as stop signals. They can be a single lens type or multi-lensed (the lenses of which can be arranged in various ways depending on the space and location). They display at least clear (green), caution (yellow) or danger (red) aspects.

Automatic stop signals ("T" signals, controlled only by track occupancy) are used in some areas to create shorter blocks between controlled signals. These display the letter "T" on a small white board on the post. These used to be "permissive" in that after stopping and then following various rules and waiting for prescribed lengths of time, the driver could re-start the train and drive on sight to the next signal. Following accidents, this has been rescinded and in terms of the rules, all "T" signals are now treated as normal absolute stop signals, which means that it is mandatory to stop and get authority before passing such a signal at danger.

At junctions the stop signals are usually topped with either a direction indicator or a route indicator (they do not have to be - the indicator may be located elsewhere). These are the "octopus" arms with a row of three or more white lights on them.

Where there is a direction or a route indicator, the "clear" (green) proceed aspect is only given when the route does not diverge (vertical white lights) and the next signal also displays a "proceed" aspect (green or yellow). If there is a turn-out set, a "caution" aspect (yellow) will be shown along with the direction or route indicated to be followed.

Where a direction indicator is used, it only shows the state of the first set of points. Where a route indicator is used, it shows the route set up. In this case there will often be more than one arm to the left or right. Each successive arm indicates the next successive route - not a sharper corner or a "U-turn"! In more complex situations, as on the approach to major station, a "theatre" indicator is often used which displays an abbreviated route name or a platform number.

As speeds have increased on some routes and higher-speed points installed, it became necessary to warn the driver as to what sort of points he is about turn-in or turn-out over (this is a rare example of a kind of speed control indicted by signals in SA). So, here four aspect signals are required. A 'green and yellow' (green above yellow) aspect is displayed to warn of a turnout over higher-speed points. A 'double yellow' (yellow above yellow) warns of a turn-in or turn-out over lower-speed points (different to the UK where a double yellow is an advance warning that the next signal displays a single yellow). Both aspects are only displayed when the next signal is displaying a "proceed" aspect (green or yellow). A single yellow is displayed if the next signal has a "danger" (stop) aspect.

Incidently, one other difference in SA compared with the UK is that SA does not use the "approach release" aspects used in the UK to warn of a turn-out at many junctions. Diverging (turn-out) routes always show a caution aspect (at least one yellow) with the direction or route indicator, never a green with diverging "feather" as is often the case in the UK.

A 'red over yellow' aspect indicates to the driver that the train is being admitted into a goods yard or siding and to travel very slowly (pass the signal but be prepared to stop up ahead).

There are many more complex signal aspects that may be encountered - but more rarely and only in certain areas or on certain routes (including, 'white and yellow' or 'white and green'; 'white and double yellow' or 'white and green and yellow'; 'red and blue'; etc) - most too complex to describe here.

Also do not forget that in many instances, the signal post may also have a one-position-light shunt-signal mounted below the main lenses. Also where a shunt signal is needed and there is no main signal nearby, a ground-level-mounted two-position-light shunt-signal may be installed.

Hope this helps.
"To train or not to train, that is the question"
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Steve Appleton
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Re: Pietermaritzburg to Ladysmith Signals

Post by Steve Appleton »

"To train or not to train, that is the question"
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