InnoTrans 2022 (38)

At InnoTrans 2022, Siemens Mobility was the only exhibitor presenting a train for the metro - specifically it has shown two cars of the new X-Wagen type for Wien. At the end of 2017, Siemens signed a contract with Wiener Linien (WL) for the supply of 34 six-car units, also including maintenance contract for 24 years (essentially their entire planned lifetime) and including an option for a further 11 trains. The end car 3711 and the intermediate one 3511 on display belong to the sixth unit (the end cars are numbered 3701 + 3702 upwards, starting with the first unit); at the time of InnoTrans, the seventh trainset was being completed.

The 111,250 mm long trains over couplings are fully ganwayed and have a 2'2' + Bo'Bo' + Bo'Bo' + Bo'Bo' + Bo'Bo' + 2'2' axle arrangement, a maximum speed of 80 km/h and a starting acceleration of 1.2 m/s². The asynchronous traction motors are rated at 180 kW, giving a total power of 2,880 kW. The train is fed from a 750 V DC third rail. 

The bogies with the rubber-metal primary and pneumatic secondary suspension are manufactured at Siemens Graz. The wheels have a diameter of 840 mm when new, and the axle weight is 10.9 t (compared to 11.4 t of the previous V-Wagen generation). The electrodynamic brake is effective until the train comes to a complete stop, reducing wear on the disc brake.

The brake units themselves are of a completely new type, as Siemens Mobility together with Liebherr Transportation developed a compact electro-hydraulic brake to replace the pneumatic brake. A fully electronically controlled device also known as Brake-by-wire meets the highest Safety Integrity Level SIL4, utilising Liebherr’s know-how in electronically controlled aircraft components (so-called fly-by-wire).

Although the new Type X trains are equipped with a driver's cabs and LZB 503/513 ATP for use on the U1 - U4 lines, they are also being considered for service on the constructed U5 line between Frankhplatz and Karlsplatz, which will introduce fully automated driverless train operation in Wien once it is completed around the end of 2026.

The bodyshells are made of aluminium and are 2,850 mm wide. They are manufactured at the Wien-Simmering works, where final assembly also takes place. The height of the unit is 3,545 mm above TOR, the floor is 1,000 mm above TOR. The distance between the bogie pivot centres is 12,000 mm for the intermediate cars and 12,200 mm for the end cars. Each of the cars has three pairs of double plug-sliding doors with a clearance of 1,305 mm. An extendable bridge is built into the threshold of each door to bridge the gap between the train and the platform.

There are 200 seats in each train. The seats have different arrangements, mostly 1 + 2 or 2 + 2 in bays, but some of them are placed transversely. The train also offers space for 728 standies at a density of 4 persons per m². There are also multifunctional areas for strollers, oversized luggage and wheelchairs. The interior is illuminated with LEDs and thermal comfort is maintained by air-conditioning units. 

Compared to previous generations of Wien metro trains, the X-trains have an advanced passenger information system consisting of LED panels mounted on the ceiling and displays above all doors. The displays provide travel informations, including details of interchange connections, while the station-specific information displayed, such as directions to exits and connections, is individual to each door of the train, reflecting the door position within the platform on which the train stops.

The very first X-Wagen bodyshell was unveiled at the Simmering plant on 22 August 2019, and less than a year later, on 3 July 2020, the two completed cars were then officially introduced there. Between 15 and 30 June 2020, two cars (3701 and 3501) were tested at the RTA Rail Tec Arsenal. In July 2020, the first six-car unit was completed on the tracks at the WL depot and testing began.

For the approval of the new type is responsibile MA64 department of Wien City Hall (Bau-, Energie-, Eisenbahn- und Luftfahrtrecht), which oversees compliance with building, energy, rail and aviation laws. Within Austria, underground trains belong under the legal framework of tramways. The first "passengers" during the test operation were representatives of the Wien City Hall, Wiener Linien, Siemens and the media on 14 April 2021. On 6 May 2021, the "X-cars" were named FeliX in an online survey involving approximately 44,000 voters.

On 6 October 2022 Wiener Linien announced that the tests had been successfully completed and that type approval and start of the regular service was expected before the end of 2022; however, this has not yet happened. Last December, WL had six units in service; in mid-February, the transport company reported seven trains awaiting the start of operations.

The FeliXes are to be first introduced on the U3 Line. This will enable the aging U type trains, known as the "Silberpfeil" (Silver Arrow), produced by SGP between 1972 and 1995, to be withdrawn gradually. After the introduction of the X type on the U5 Line in the fully autonomous GoA4 mode, it is planned to remove the driver's cabs, which will increase the capacity of each train by 24 passengers. Delivery of the entire 34-strong batch is scheduled to be completed in 2030.

Brake-By-Wire

The electrohydraulic brake has replaced the pneumatic brake in the Type X units, the first such application on a Siemens Mobility train. Also known as "brake-by-wire", the system was developed by Siemens Brakes, a separate department within Siemens Mobility since 2003, in cooperation with Liebherr Transportation.

After more than 150 years since the invention of the air brake by Westinghouse and after a long period of optimalization of the conventional air brake, an electrohydraulic (eh) alternative is now available for the first time ready for batch use, representing a technological leap in the field of braking systems. The electrohydraulic brake eliminates the need for compressors, air pipelines and pneumatic components to control the brake.

With a decentralised architecture and compact design, braking force is generated directly in the hydraulic wheel brake unit (actuator), which is integrated into the bogies in the same mounting space like the conventional air brake unit and has the same mechanical interfaces. The control of the eh-brake is only provided by a 24 V DC power supply and via a CAN interface. This reduces vehicle weight, while space previously required for air brake components can be used for other subsystems; maintenance costs are also reduced. 

But there are also benefits directly in operation, where the time required to prepare the train and running at the beginning of a shift is reduced. This means that the driver can start his shift a little later or, in the case of trains in automatic operation, the train can run on the line earlier, offering greater flexibility. The parameters of the eh-brake also present additional benefits for the automation of operations, especially in terms of braking performance and stopping point accuracy, which is comparable to the electrodynamic brake. 

The electrohydraulic brake is released faster than the pneumatic brake, so the train needs less time to move after the entrance doors are closed. At intervals of 60 to 90 seconds between trains, the saving of every second is a significant improvement. Wiener Linien will be the first operator in the world to use this brake system both in conventional driver-controlled operation and later in automated operation on the new U5 Line.

Siemens is now also working on other applications, for example for EMUs. A prerequisite for the expansion of eh-brake in rail transport is that future vehicle tenders specify only functional and technology-neutral brake requirements instead of the current practice of directly specifying air brakes.