Under the Name TWINDEXX Swiss Express, Bombardier produced a total of 62 double-decker high speed trains for the SBB. SBB also calls these trains “FV-Dosto”. In contrast to the TWINDEXX Vario that is being offered for commuter traffic, this variant has traction motors distributed along the train. In both four- and eight-car variants, three quarter of all cars are equipped with two traction motors in one of the bogies, making 3,750 or 7,500 kW in total.
A special feature of these trains is the roll compensation that is not a tilting system as such, but compensates for the rolling movements in curves and allows for higher average speeds. For use in inter-regional service, there is the four-car variant IR 100 with a total length of 100 m and the eight-car IR 200 with a total length of 200 m. The IC 200 is being used for long-range intercity traffic and also consists of eight cars, including a dining car. The official type designations of SBB are RABe 502 and RABDe 502, where the D designates the additional dining car.
Although these trains were originally planned to be introduced in 2013, this only happened in 2018 due to various problems. These included software issues, but also problems with the roll compensation. Especially passengers in the upper deck complained about great discomfort in certain curves. So SBB decided to disengage the system for the time being and to lower curve running speeds in exchange for a better passenger comfort. In the near future, the suspension system is to be upgraded, allowing to remove the roll compensation equipment altogether.