SBB operates the most heavily and densely used rail network in the world. Every day, several thousand trains run on SBB’s network of over 3,000 kilometres, delivering around one million passengers to their destinations. SBB also transports over 100,000 tonnes of freight on its rails each day.

Train protection plays an important role in ensuring that passenger and freight trains run safely and on time over this busy network. 

Three systems are currently used for train control in Switzerland, with a further distinction between ETCS Level 1 and ETCS Level 2:

• Integra-Signum: this warning system alerts the locomotive driver at the distant signal when approaching a stop signal or when the speed needs to be reduced. If the driver fails to observe a stop signal, the train brakes automatically. This system operates at all the main signals on the entire rail network.
• “ZUB”: This system complements Integra-Signum by continuously monitoring the speed of the train between the distant and main signals. If the driver fails to reduce the speed between the signals, the train brakes are automatically deployed. This ensures that the train is brought to a halt before a danger point (e.g. a crossing).
• “European Train Control System (ETCS) Level 1”: This train protection system largely corresponds to the principles of "ZUB" and "Integra-Signum". It is also used with track-side signals but takes the European approach of ETCS and its basic principles. In Switzerland, the LS (Limited Supervision) specific operating mode is used for ETCS Level 1.
• European Train Control System (ETCS) Level 2: with this train protection system, the movement authority, speed information and route data are displayed in the driver’s cab (cab signalling). This means it is possible to dispense with lineside signalling apart from a few indicator panels. The train movements as well as the maximum speed for the local section, the train's maximum speed, the correct route and the direction of travel are all continuously monitored by the radio block centre.

There are a large number of different national train protection systems in Europe for historic reasons. For a train to be able to run from Rotterdam to Genoa, it currently still requires several different train protection systems. ETCS (European Train Control System) was developed as a European standard to harmonise technologies and promote rail transport in Europe, thereby strengthening the competitive advantage of rail transport. 

The large number of train protection systems used in European countries is to be replaced by a technologically and operationally standardised solution to facilitate frequent and fast cross-border train movements throughout Europe.

With the rollout of ETCS Level 1 completed in 2018, Switzerland is the first country in Europe to fully meet the requirements for European interoperability. 

Thanks to the network-wide use of ETCS Level 1 and Level 2, the entire Swiss standard-gauge network can now be operated without the use of an additional national train protection system.