Siemens first produced the Viaggio Comfort railcars in response to a request by the Austrian Federal Railways for locomotive-hauled push-pull trainsets for its upcoming Railjet high-speed rail service. Typically, high-speed rail services use electric multiple units, but ÖBB had recently purchased a fleet of Siemens EuroSprinterelectric locomotives that it wanted to continue to use. After a bidding process, it was announced in February 2006 that the Siemens Viaggio Comfort was the best design as well as the least expensive. The initial February 2006 order was for 23 sets of 7-coach trains, which was followed by a second order by ÖBB for 44 more sets in September 2007. The total value of the order was €798 million for 469 passenger carriages. The industrial design company Spirit Design was contracted to provide an exterior and interior design. The shape of the forward end of the control car was derived from the design of the Siemens EuroSprinter locomotives that the trainsets would be paired with. The trainsets were built at the Siemens factory in Maribor, Slovenia and the first unit was completed on 15 September 2008, and put on display in several locations including the InnoTranstrade fair before beginning test runs in late 2008. The first Railjet commercial service started on 14 December 2008. Between September 2011 and May 2012, Czech Railways negotiated to have seven of the trainsets ordered by ÖBB transferred to it, for use on its high-speed rail service which would also be called Railjet. The Viaggio Comfort railcars went into service with ČD on 15 June 2014. In July 2018 the Czech Railways ordered 10 5-car trainsets for domestic services. They should operate on Prague - Cheb line from 2021. These units have decreased maximum speed to and they haven't the control car.
Trainsets
Most Siemens Viaggio Comfort railcars are configured into semi-permanently coupled trainsets with open gangway-style connections between cars but with standard couplers on the outer ends of the trainset for connecting the trainset to locomotives or other railway equipment.
Railjet trainsets
A Railjet trainset consists of seven individual coaches: four coaches with economy seating, one coach with a restaurant and a first class seating section, one coach with first class seating, and a control car with a first class seating section and a business class seating section. The trainsets were manufactured by Siemens in Maribor, Slovenia, with final assembly being completed by ÖBB's technical services department in Simmering, Vienna. The passenger cars are equipped with electro-pneumatic disc brakes, as well as electromagnetic track brakes, and a parking brake. The driving trailer also has a manually operated brake using the disc brakes. Primary bogie suspension is by coil spring, and secondary suspension is pneumatic. Brake equipment is supplied by Knorr-Bremse, air-conditioning by Liebherr, and doors, carriage connections, toilets and seats are manufactured by other subcontractors.
The Siemens Venture is based off the earlier Siemens Viaggio Comfort railcars in use in Europe, but adapted for the North American market. The cars entered service with Virgin Trains USA in 2018. Railcars are currently on order for the US states of California, Illinois, Michigan, and Missouri for use on their state-supported corridors operated by Amtrak and Canada's Via Rail for use on its Québec City–Windsor Corridor. They are being built in Siemens' Mobility North American factory in Florin California.
