ComfoAccess was developed by Trapeze in partnership with Albis Technologies, Switzerland, and is based on a card the size of a normal credit card, which is carried by the passenger. Detection fields positioned around the passenger doors identify whether a passenger is entering or leaving the train.

When the passenger boards the train, the card is detected and a trip transaction is automatically registered for each section of the journey, which is saved in the onboard computer. This means no passenger interaction or operation is required.

The passenger is charged only after they have completed the journey, and they can access trip and transaction history if required. A prepaid option is also available, and users can even pay by cash at a ticket office to top-up the card if desired.

The so-called Be in/Be out (BiBo) technology is currently being trialled by Swiss Federal Railways (SBB), and is a third-generation development of the EasyR!de system trialled in Switzerland and the more recent Allfa-Ticket evaluated in Dresden in 2005.

Passengers interface with ComfoAccess using a smartphone app, which enables the user to select fare options and also displays timetables, and real-time passenger information.

The onboard computer can detect up to 300 cards every 15 seconds, meaning it can quickly establish how many card users are boarding and alighting at each stop.

Trapeze says BiBo fare collection allows public transport operators to operate flexible pricing systems which reflect actual utilisation of services.