THE SIGNAL BOX

SIGNALS

SEMAPHORE SIGNALS

6. Junction signals

At junctions, individual arms are generally provided to indicate which route a train is to take. The arms are usually mounted on separate posts (dolls) on a bracket or gantry, alongside each other. Combinations of the various types of signal illustrated in the preceding sections are used, according to the circumstances. The arms are generally arranged so that the higher arms apply to the higher speed routes, but occasionally the arrangement will indicate the importance of a route.

What is a junction? In railway terms, a junction can be anywhere where facing points allow trains to take different routes. Thus, as far as junction signals are concerned, there is no difference between the principles for signals provided at a junction with a branch line than those provided for connections between Fast and Slow lines on a multiple track route.

Junction signals

Signal for twi-way junction

A typical signal serving a simple junction has two arms. Here, the right-hand arm applies to the main line (fastest route) and the left-hand arm serves a branch or loop line.


Two-aspect Colour Light junction signal
Junction signal - two equal speed routes

If the both routes have the same speed limit, the arms are placed level with each other.

The design of the bracket structure, whether it be balanced, or left-handed/right-handed is of no relevance to the signals' meaning.

Two aspect Colour Light junction signal for two equal speed routes
Junction signal - three-way

This is a three-way junction signal, for routes of three different speeds or importance.

An example of route importance would be where this signal was provided as a Slow Line home signal. Possible meanings might be:

  1. Slow Line to Goods Line home
  2. Along Slow Line home
  3. Slow Line to Fast Line home.
Two-aspect Colur Light junction signal for three routes

A three-way junction signal where one of the routes leads into a siding or loop.

In this example, the miniature arm for the siding is mounted low on the post on its own bracket but it could also be mounted on the same bracket as the other arms.

Junction Colour Light signal with subsidiary signal to siding
Home signal with disc at foot of post

Sometimes, a route into a siding or loop is controlled by a ground signal mounted at the foot of the main post.

Two-aspect Colour Light with siding signal
Junction signal with arms vertically stacked

Occasionally, junction signals will be found with the arms mounted above each other. In this instance, the top arm always applies to the left-hand route and the bottom arm to the right. If there are more than two arms, they read left-to-right.

This type of signal is relatively rare, and is used only on goods lines and low-speed areas.

Two aspect Colour Light junction signal for two equal speed routes
Stop signal with Route Indicator

Another way to indicate large numbers of routes, or overcome space limitations, is to provide a Route Indicator to accompany a single arm.

As the signal is not as distinct as a multiple-arm junction signal, route indicators are only used in low speed areas.

Two-aspect Colour Light signal with Route Indicator
Semaphore   Colour Light