Trains are only allowed to enter a line from one side only. The signalmaster can only allow a departure of a train when he has the electronic key for that track. The electronic key can be handled over to the signalmaster of the other side when no train is occupied in the line.
One train (marked A) has to be signalled over the line. The signalmaster (station A) has the electronic key and can open the exit signal.
As the train approaches the station B, the signalmaster (station B) can open the entry signal
When train A has arrived in the station B, the electronic key can be transferred.
Now the signalmaster (station B) can open his exit signal for train B.
And when the train B has left the station, the signalmaster can open the exit signal for train A.
The permissive signals are locked on the direction of the train by the new lay-out. The NMBS is slowly upgrading the permissive signals to this new lay-out. For the moment only the recent lines and the mainlines are outfitted with it.
And when the electronic key is transferred to station B, the permissive signal open for that direction.
The distant signals aren't locked on the direction, but there crocodile is. The crocodile will be out of service (0V) when a train will come out of the other direction. (see also the chapter "Other signals")
The approach section of the levelcrossing are locked to the direction.
The levelcrossing has two approach section. Only one approch section is active when the levelcrossing is working in normal mode.
In this example the approach section 1 is active. Whan the electronic key is handded over to the station B, the approch section 2 will become active.
By maintenaince work on the track none of the approch sections will be active and only when the (maintenaince)- train is in the middle section, the levelcrossing will operate and close the barrier.