Automatische treinbeïnvloeding
When the circuit is closed by the train's front wheels an electromagnetic field is created with each pulse.
These fields electromagnetically energise two coils in front of the leading axle which feed the pulses to the ATB-system.
(out of order) The speed limit enforced by ATB-EG is presented to the driver by a row of lights, with the current cab signal illuminated, (Mat 64, SLT, PROTOS and THALYS) which can be integrated into speedometer (ICM and SGM) or either a red needle (VIRM, DDAR and Class 1700) or yellow LED (FLIRT and GTW) on the outside of the speedometer.
According to the ATB the train is now overspeeding so it will initiate the continuous bell, informing the driver that they need to start braking.
When the train is within the 5 km/h margin of the target speed the system rings three short bells, informing the driver that they are allowed to stop braking.
Several accidents at train stations and railroad yards occurred because the driver failed to stop at a red signal and ATB did not intervene, as it had already enforced a speed below 40 km/h.
The biggest gap falls between 80 and 130 km/h, meaning ATB EG will allow a train to drive 130 km/h in a 90 km/h zone.
This system is only installed on line between Hoofddorp and Den Haag Mariahoeve and is currently solely used by Thalys trains ATB-Plus-Plus is designed to reduce "Stoptonend Sein (STS)-passages" (English: Signals Passed At Danger) by applying an emergency brake after passing a signal at danger.
It compensates the original design flaws in speeds below 40 km/h where no forced braking was possible in case of passing stop signals.
ATB-Vv (Verbeterde versie English: Improved version) is the latest evolution of ATB-Plus-Plus.
Trainborne ATB-NG equipment is also able to receive ATB-EG signals, making the system backwards compatible.
The system works by conveying movement authorization via balises between the tracks, called beacons, located next to signals and in other strategic places.
When the train reaches the target speed three short bells will sound, informing the driver that they can stop braking, and the red LED will disappear.
ATB-NG measures the traveled distance by counting the wheel rotations; therefore, the system will think the train is ahead of its actual position when the wheelspin occurs.
If a red signal clears ATB-NG will still force the train to stop and only let it creep forward until it reaches the next beacon.
[1] Beside intermediately closing of functional gaps,[2] new constructed lines will use European Train Control System (ETCS) as part of the assigned standard ERTMS.
