Simple Junction


This article will take you through setting up a basic junction and its signalling. Our examples so far have been using double main line, so we’ll continue on that theme and have a double main line junction.

The first section of this tutorial covers the laying of track at the junction. If you’re already confident with this, you might want to use the links on the right to skip this part.

1 Setting up the track

Start by laying the main line:

Next, lay the tracks for the branch line.

I’ve laid them further than necessary over the main line because I’m going to show you a reliable way to do pointwork that looks half decent. It’s not the only way to do it, but I find it works well. You might want to zoom in a little for this part (using the up arrow or your mouse’s scroll wheel, if it has one).

To create the points, we’re going to insert nodes on the up branch line and the up main line at an equal distance from the two lines’ point of intersection. We’ll then do the same for the down branch line and the down main line.

First, lay a temporary piece of track from the track intersection back up the branch line. When you drag the track, watch as Rail 3D tells you how long it is: we’ll aim for 30 metres in this example.

You can increase this distance to make the points more suitable for higher speeds, or decrease it for slower speed points.

You can let go of the mouse, and a 30 m section of track will be created over the top of the existing track:

While still in track laying mode, hover the mouse over the node at the left hand end of this temporary piece of track and press delete. Without moving the mouse, right click the branch line track below and select Insert Node:

I find this a reliable way to insert a node on existing track at a specific distance. You’re now left with an isolated node in the middle of the intersection, so repeat the process to measure out a new node 30 m along the main line:

We’re now finished with that isolated node at the track intersection, so you can hover the mouse over it and press delete to remove it.

To finish off the points for the up line, simply create a new piece of track between the two nodes we just measured out:

You can also delete the extension of the up branch line over the main line now, as we’re finished with that also:

To get the points for the down line, you can insert nodes adjacent to the others we just created (by right clicking on the track spacing markers and selecting Insert Node):

As per the up line, join the tracks up to make the points, and delete the extension of the branch line. The final result looks like this:

2 Placing signals

If you recall the Basic Station Crossover on creating a crossover at a station on double track, you’ll remember that we needed to use some signals to control movements around the crossover. This was to prevent trains changing tracks and crashing into each other.

With a junction like this, we have the same situation. If a train is moving from the main line to the branch line or vice versa, we need to prevent other trains from running into it while it changes tracks.

To do this, we need to insert signals wherever trains can enter the junction. First we’ll insert some new nodes for these signals:

Now place a new signal on each of these nodes:

For each signal:

  • set the Controlled option (because they all govern movements over points)
  • use the uk model (this is probably the default model anyway, as set in File > Properties)
  • make sure Direction is correctly set (i.e. pointing towards the junction)

As an example, the settings for the signal on the branch line should look like this:

You can now go ahead and place signals on the remainder of the double track, just like we did in the Basic Through Station.

The only thing left to do is tell Rail 3D which trains should take the branch line. Open the Edit Node dialog by double clicking the node for the facing points at the junction, and enter the route name(s) of train(s) that should be sent to the branch line:

With this example, trains on route “2K80″, “3K45″ and any routes that start with “9T” will be sent to the branch line.

3 Testing the layout

I added a couple of trains to the main line to test the layout. In the following screenshot, the train in the foreground is on route 9T19 and has been routed to the branch line. Another train travelling in the opposite direction is waiting on the main line for 9T19 to clear the junction:

4 Adding a junction indicator

If you’re familiar with railway signalling you’ll know that signals often indicate one way or another whether the route has been set for a diverging move (i.e. to another track).

Using colour light signals, the uk practice is to use what’s called a “feather” above the main signal aspect. The feather is a row of five white lights pointing diagonally in the direction of the diverging move. If the route is set for the diverging move, the feather is illuminated.

Adding a feather to our junction signal is very easy. Open the properties for the signal controlling the diverging moves and click the Type button to find the ukjr signal:

The “jr” here stands for “junction to the right”, so if our diverging tracks went off to the left we’d use the ukjl signal model instead.

Now stand back and watch as the “feather” illuminates automatically for diverging routes:

5 Which route is the junction route?

So how does Rail 3D know which route is the junction route? Well, it all depends on which route you select as the default route at the points.

The junction route is assigned to any route that is not marked as the the default route. For points where trains in the facing direction always take the same line, we could just set the default route accordingly. But in order to get the signals to show junction indications properly, you sometimes have to set the default route for the wrong line and type an asterisk in the Other Route box to get all the trains to go the other way.

If necessary, you can manually define which route is the “junction” route (i.e. the diverging route). This can be done by right clicking on a node somewhere on the junction route just after the junction, and selecting Signals > Mark J point.

6 Taking it further

We won’t cover it here, but semaphore signals are the classic example of signals showing routes set for diverging moves:

If you’d like to, you can add in speed limits for trains going to/from the branch line, as they are unlikely going to be allowed to traverse the points at full main line speed. See the end of the Two-track Terminus for a brief overview of how to do this.

31 January 2007