Controlling rail traffic

Thousands of trains run on our tracks every day. For instance, 1,100 trains run between Brussels-Nord and Brussels-Midi every day. So it is essential to find an effective and efficient way of controlling rail traffic safely.

1. How is rail traffic controlled?

The three main elements in controlling rail traffic are:

  • The light signals and signs along the tracks, which the train driver has to obey
  • The signal boxes, which operate the signals and points, thereby creating a safe path for each train
  • Traffic Control, which directs rail traffic when delays, disruptions, accidents and incidents occur.

2. Directing rail traffic safely

Signal boxes control rail traffic at regional level

They plot a train's journey from A to B according to the timetable or after consultation with Traffic Control. They set the points to the correct position and operate the signals, so that trains are directed to the assigned track. 
In the event of accidents, dangerous situations or works on the track, signal boxes take steps to ensure that no trains can end up on a track on which works are taking place or where an incident has occurred. This ensures the safety of passengers and staff on and around the tracks.

Hi-tech traffic management

A project to modernise signal boxes has been under way for several years. The aim? To make traffic management safer and more efficient by merging small, manually operated signal boxes into fewer large, ultra-modern signal boxes. 

These new signal boxes use modern ESB (Electronic Signal Box) technology. This system proposes a route for every train, which the operator can then either accept or adjust. The operator therefore no longer needs to input excessive amounts of information manually. Such computer-supported decision-making processes ensure safer and more efficient rail traffic.

These systems are intended to support our people, not make them redundant. There will always be certain situations in which human intervention is necessary.

Traffic Control coordinates rail traffic at national level

They divert rail traffic when delays, disruptions, accidents and incidents occur and are in constant contact with the signal boxes and train drivers.

How is rail traffic managed when there is an incident?

1. Traffic Control assumes responsibility for coordination. After consulting the signal box, they determine which train may depart first, whether the train needs to change track, whether a train has to be cancelled, etc.

2. The signal box then provides modified routes for the trains affected. They set the points in the correct direction and control the signals. That way, the safety of all rail traffic is guaranteed and, in principle, there can never be one train coming from the right and another train coming from the left on the same track at the same time.

Safety communications

Safety communication between signal boxes, Traffic Control and train drivers is crucial in order to keep rail traffic running safely.

That is also why the NATO alphabet is used in such communications.  Suppose a train driver has a problem and calls Traffic Control. He is at signal N.16. If he does not use the NATO alphabet, Traffic Control might think he said M.16, which could lead to an unsafe situation. Instead, using the NATO alphabet, the train driver will report that he is at signal "November One Six", so there can be no misunderstanding.


Nato alphabet

3. Signals and signs along the tracks

The signal boxes communicate with the train driver via the signals along the track. He therefore knows when to stop and when he may continue.

These are the main light signals

•    a green light means that the train may travel onwards
•    a red light means that the train must stop
•    a signal with a double yellow light warns the train driver that the next signal may be red and he should slow down.


Sign with a double yellow light

Other combinations of these lights are possible, imposing additional restrictions on train drivers.

There are also different signs along the tracks which give the train driver additional "fixed" instructions about his journey. There are speed-limit signs, for instance, which show the permitted speed for the train.


Speed limit sign

Cab signalling

Increasing use is being made of "cab signalling". The train driver receives all relevant information on a display inside the train. 

More information about these systems

Safely from A to B

Around stations or points, the signals are always controlled by signal boxes. However, where there are no stations or points and where trains must continue travelling, it is the trains' movements that control the signals.

What does this mean in concrete terms? The rail network is divided into sections or zones on which only one train may travel. As soon as a train starts to move, it automatically creates a zone in which the signals for other trains will be red. No other train may then enter that zone.
This avoids two trains travelling in the same direction on the same track, and catching up and colliding with each other. 

In order to avoid two trains travelling in opposite directions on the same track, one of the two directions of travel is also blocked. The signals in that direction of travel are all set to red.

Of course, a problem or fault must never lead to an unsafe situation. If something goes wrong with a signal, it will automatically change to red, even if there are no other trains nearby. Until we know that the signal is working perfectly again, the train driver may only move forward after receiving formal permission from the signal box.