InnoTrans 2024 report (21)

Stadler at InnoTrans 2024 has again presented a wide range of vehicles representing its extensive production portfolio, but a special surprise, announced only in June, was the RS ZERO, a modern "reincarnation" of the RegioShuttle RS1 diesel railcar. Less than 500 of RS1s were produced first for Germany and later for the Czech Republic.

RS1's history began in the early 1990s as part of the activities of many manufacturers aiming to bring innovative types of trains for regional and local transport. Development of a four-axle railcar was initiated by the then Berlin-based ABB Henschel Waggon Union. The complete development of the vehicle, with the exception of the bogies, was carried out at the Výzkumný ústav kolejových vozidel (VÚKV), the Railway Research Institute, in the Czech republic, according to the design of the project. The characteristic feature of the car was the truss structure of the steel bodyshell giving it a typical diagonal window columns.

In 1996, the joint activities of ABB and Daimler-Benz were merged to Adtranz, which completed the first RS1 cars at its Pankow works, in the same year. In 2001 Adtranz was acquired by Bombardier and became part of its Transportation (BT) division, but for reasons of market protection, BT was forced to give up the Pankow plant. It was subsequently acquired by Stadler who held production of the RS1s until 2013, when the cars ceased to be offered as they did not meet the new TSI for crashworthiness.

Although the European market seems there is no demand for small vehicles, some interest does exist. That's why Stadler is coming up with RS ZERO. The major change is being an exclusively carbon-free (locally), specifically using hydrogen or battery to power the vehicle.

The hydrogen prototype

The RS ZERO prototype on display, designated 90 80 0550 000-8, is hydrogen-powered, but not with fuel cells: a cheaper solution with two combustion engines burning hydrogen is applied. Each Deutz engine, located in the PowerPack under the driver's cabs, powers an ABB traction alternator, from which a traction battery, situtated under floor, is recharged via an ABB traction converter. The traction motors of the adjacent inner axle are then fed from the battery. The traction motors have an output of 300 kW and are supplied by Traktionssysteme Austria (TSA).

The power transmission is thus no longer hydromechanical as in the case of RS1 (a B'B' axle arrangement), but electric, which is therefore also a precondition for the battery version of the RS ZERO, using as power source batteries only. The bogie arrangement is now (1A)' (A1)' and the railcar is referred by the manufacturer as HEMU 1. The designation of this vehicle as Class 550 characterises, according to the German scheme, cars/units with battery or hydrogen drive (the Class 6xx is reserved for DMUs or diesel railcars).

A two-car variant of the vehicle, HEMU 2, is also possible, in that case both cars are of the same design. The length of the RS ZERO is 27,400 mm over the couplings, the width of the bodyshell is 2,820 mm and the height of the car is 4,275 mm above the TOR. The two-car unit will have a length of 53,140 mm. The top operating speed in both cases will be 120 km/h; this is sufficient for local lines, according to Stadler, and the higher design speed would also require more massive and therefore heavier crash elements. The RS ZERO hydrogen car has a maximum power output of 600 kW at the wheel (1,200 kW for the two-car unit), a maximum tractive force of 70 kN (140 kN for the unit) and a starting acceleration of 0.95 m/s² (in both cases).

The axle-load is stated to be less than 18 t (like for the battery version). In order to keep the weight as low as possible, the vehicle battery has been omitted so that the auxiliary drives are powered directly from the traction battery. The working range of the HEMU1 railcar is claimed to be more than 700 km per filling and over 1,000 km for the HEMU2.

The interior

The manufacturer has taken inspiration from the original design of the RegioShuttle RS1 for the bodyshell design, so the typical trapezoidal windows are retained. However, they are just a design element as a reminiscence of the original vehicle, as the RS ZERO's bodyshell is made of extruded aluminium profiles, which means the window openings are milled into the welded sidewalls and the diagonal columns no longer have a direct load-bearing function.

The new vehicle complies with the current TSI standards and also complies with the EN 15227 C1 for mainline vehicles. The bogies have a primary suspension consisting of steel coil springs, the secondary suspension is pneumatic. The wheels have a diameter of 760 mm when new.

The thresholds of the entrance doors are 600 mm above the TOR, as is the floor in the low-floor section of the vehicle. The floor above the bogies is situated 1,190 mm above TOR. The width of the entrance doors is 1,300 mm and each door is fitted with a retractable step. The seating capacity in the air-conditioned interior varies depending on whether the car is equipped with a toilet, or not. In the version with a barrier-free toilet in the low-floor section 59 seats are available, including folding seats; the two-car unit can offer up to 148 seated passengers. In configuration without a toilet, the seating capacity increases to 75 and 165 respectively.

The prototype is equipped with seats from BORCAD cz, namely VISIO seats and the new FLEXIO REGIONAL seats. The latter has ergonomics modified to allow its arrangement facing each other with a pitch of 1,650 mm. In the elevated section above the bogies, alternative solutions using the FLEXIO REGIONAL concept, also developed in cooperation with BORCAD cz, was presented, in the form of two-seat units in a quasi-compartment, or the longitudinal seating at a table with a view of the landscape.

Stadler states that when designing the RS ZERO family, considerable emphasis was put on the use of environmentally friendly materials, e. g. the flooring is made from 98 % renewable raw materials and is free of synthetic rubber and plasticizers. The wall cladding is made from recycled materials including PET bottles.

The RS ZERO with a battery

The battery version of the RS ZERO will differ from the hydrogen version, in terms of parameters, mainly by the presence of a pantograph above one of the driver's cabs and a roof-mounted traction transformer to allow the charging of traction batteries (located as well under the floor), primarily from a 15 kV 16.7 Hz overhead wire.

However, Stadler also offers the possibility of using 25 kV 50 Hz, 1.5 kV and 3 kV DC voltage systems. Battery version will also be offered both as a four-axle car (BEMU 1) and as a two-car unit (BEMU 2). The service range of a BEMU is stated to be 80 - 100 km per charge in case of BEMU 1 and 90 - 180 km for the two-car BEMU2.

Testing

The hydrogen prototype has been built at the Pankow factory, where the first presentations to potential customers took place at the end of August. In terms of future test operation with passengers, an agreement was signed at InnoTrans between the Thuringian Ministry of Infrastructure and Agriculture, the operators Erfurter Bahn and Süd-Thüringen-Bahn, and Stadler on the intention to use the RS ZERO hydrogen prototype in Thuringia.

As part of a pilot project, the prototype is to be used in passenger service on non-electrified lines from mid-2026, with either Erfurter Bahn or Süd-Thüringen-Bahn services, depending on the location selected. The purpose is to test whether the RS ZERO meets the requirements of passengers as well as the technical and economic expectations of the operators who currently operate RS1 railcars.

Stadler has high hopes for the new vehicle, so it will be interesting to see how it performs in the target markets, which include Italy, France, Poland and the Czech Republic in addition to Germany.