will inform the driver of the oncoming speed reduction and upon entering that block the ATB will change to the target speed. According to the ATB the train is now overspeeding so it will initiate the continuous bell, informing the driver that he needs to start braking. Once again, if the driver does not brake within 3 seconds the ATB will initiate an emergency brake application. The system will stop the warning once the driver is braking sufficiently, this is checked by means of the so-called remcriterium (English: brake criterion). The remcriterium is based on either the brake pipe pressure, brake cylinder pressure or the position of the brake lever. This should ensure the train reaches the target speed before the next block, but it often proves inadequate. When the train is within the 5 km/h margin of the target speed the system rings three short bells, informing the driver that he is allowed to stop braking. Failsafe After passing a red signal and entering a section already occupied by another train, the track circuit is already shorted by the other train preventing the signal from reaching the train passing the red signal. Therefore, the absence of a signal is interpreted as the most restrictive signal, making the system fail-safe. To allow driving on sight onto occupied track, which cannot be discerned from passing a red signal using a system like this, receiving no signal was chosen to be interpreted as a speed limit of 40 km/h. Design limitations ATB-EG has a number of drawbacks when compared to modern systems like ETCS ATB-EG does not enforce speeds below 40 km/h. The system only has 5 speed settings, leaving room for overspeeding. ATB-EG does not allow speeds above 140 km/h while there are lines designed with a higher speed limit. The braking power enforced by ATB-EG often proves insufficient. Rails are also used as return for the catenary, it is therefore possible for electric trains to interfere with the ATB signal. ATB EG will only work with good contact between the rails and train wheels. One of the early system's design limitations was the inability to enforce speeds below 40 km/h. 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. Strange as this limitation may seem,