Stadler GTW

First Generation: Goldenpass Be 2/6 7003 Blonay at Blonay (CEV-Bahn)

The Biel–Täuffelen–Ins-Bahn near Bern, Switzerland was looking for a lighter train model to replace its aging fleet, so that a low floor system does not require heavy installations on the roof. Based on that requirement Stadler came up with a concept of placing most of the equipment in a central unit between the seating cars. While the BTI-Bahn tracks are meter gauge, Stadler presented the first prototype in 1995 set on standard gauge rails, and the Mittelthurgau-Bahn tested three prototypes on its standard gauge network during 1996. The rolling stock for Mittelthurgau was later expanded to 10 GTW 2/6 (built 1998-1999) that are now part of the THURBO fleet (the three prototypes were sold to Italy). The next lots were produced in meter gauge, and were delivered to the BTI-Bahn and the CEV-Bahn (Chemins de fer électriques Veveysans) in 1997 - although the BTI-Bahn was first to order any GTWs with its 7 trains, the CEV-Bahn ordered the biggest lot of the first generation with 20 trains.

In 1998 the Linzer Lokalbahn (Austria) placed an order which needed to be modified to conform to the DIN 5510 class 2 safety standard, as well as different electrification. These 8 trains were delivered in 2000 from the Swiss facilities and an option of 6 more trains was fulfilled in 2005. Another modification was done for the River Line (New Jersey) with an order of 20 DMUs delivered in 2002/2003 from the Swiss facilities.

Second Generation: HLB train 509 108 in Frankfurt

During that time the Hessische Landesbahn (HLB) in Germany was also looking at the new system but actual procurement was delayed until the second generation. In the beginning, Stadler was cooperating with ADtranz/DWA im Germany with the initial batch produced in 1999 at DWA Bautzen (Saxony). Its headshape design follows the style of the Deutsche Bahn trains as they were already on production at DWA, and eventually the DB Regio services also ordered a batch of 30 trains of a similar type as the 30 trains ordered by the HLB (only the height of the low floor section differs). The full series were then manufactured at the new Stadler Pankow (Berlin) facilities being built in 2000 by a joint venture with ADtranz. Stadler acquired their shares in 2001 and the final vehicles were delivered from that plant in 2001 by Stadler alone.

The second generation can be easily distinguished by its round headshape made from FRP (glass-fiber reinforced plastic). These follow the DB design being produced since 2000 for other customers as well, for example a batch of 12 trains went to Athens (Greece) in meter gauge (ordered in 1999, delivered since 2003). With the second generation the available options for GTW trains expanded - meter gauge vehicles can be ordered in a 2.2 or 2.7m width and the standard gauge vehicles in a 3.0 or 3.1m width. Also the GTW 2/6 may be expanded with an additional bogie car making it a GTW 2/8.

Third Generation: Stadler GTW 2/6 (ATR 100) diesel electric for Societá Automobilistica Dolomiti (SAD), used on the Ferrovia della Val Venosta, at Mals station in Italy

The third generation has minor modifications to the headshape but the more important changes were made to the power module - the electric variant now has 700-800 kW (instead of up to 520 kW) and the diesel-electric variant is available as a DMU-2 with two generators instead of one. This allowed increasing the maximum speed, which was a requirement of Italian customers; in Italy this type is known as ATR 100. The Vinschgerbahn (Bolzano) was the first to order twelve DMU-2 in 2004, extended by eight vehicles of the same type for the Udine-Cividale line (Padova), also in 2004. The DMU-2 concept impressed the Arriva operator in the Netherlands which ordered 43 trains in 2005 asking for some further developments - the modified type sold well to other operators in the Netherlands and abroad, both as DMU and EMU variants.

The fourth generation came along with new regulations in the EU that increased the crash worthiness requirements (see EN 15227). Trains had to comply with these requirements by 2008 (see 2008/57/EC). This is the same year that much of the production was moved to the branch factory in Siedlce, Poland.

551 units have been sold until 2011[1] and are in use in Austria, France, Germany, Italy, the Netherlands, Slovakia, Switzerland and the United States.

Because of the crash worthiness requirements, the GTW gained weight over time. In the concept of 1998 it had 483 kg per seat while in 2010 the base model 2/6 had increased to 660 kg per seat. This was higher than a Flirt ET 22 in 2007, at 639 kg per seat. As a consequence the manufacturer saw its biggest customers, Arriva and Connexxion, switch over to the Flirt models for the following deliveries in 2012. Only some replacements for diesel-electric and cog-wheel trains followed after that point in time. For those application areas Stadler introduced the WINK concept (or Flirtino) in 2018. Flirt and Wink are the next generation models that can support updated crash worthiness requirements. Like Stadler's GTW family of multiple-units, Wink has a central power module containing the energy generation, traction and auxiliary systems, while the frame and other parts are derived from the Flirt models.

Driver's cab of Thurbo RABe 526 799 at Sankt Gallen train station

Stadler GTW is family of vehicles which differ externally, in the various designs of the head of the vehicle (from angular to streamlined), and also in the different designs and power units that drive them. They also come in different gauges and as rack railway vehicles. The basic version is the GTW 2/6, a railcar which conforms to UIC standards. "2/6" means "two of six axles are powered". The GTW 2/6 is used for example by Deutsche Bahn as Baureihe 646 (Series 646) and by Swiss railways as RABe 526.

The basic concept is rather unconventional: the car is driven by a central "power module", also known as a "powerpack" or a "drive container", powered on both axles. Two light end modules, each with a bogie, rest on the power module, which produces useful traction weight on the driving axles. The end modules also use the space very effectively, although the railcar is divided into two halves by the power module. Most units have a path through the drive container for passenger access. The end modules can be delivered with standard pulling devices or buffer gears, or with central buffer couplings. They are built with a low-floor design except above the bogies and at the supported ends (more than 65% of the railcar is low-floor). All of the usual comforts to be expected in a modern local network railcar are provided, such as air conditioning, a multi-purpose room, vacuum toilets (in a washroom suitable for the disabled) and a passenger information system. The GTWs can be Diesel-electric or electric-powered (via overhead wires or third rail).

Although the traction is good for the powered bogies the concept has the same problem as other light railcars with the brakes on the non-powered axles having lower grip than traditional railcars. This has led to actual restrictions when leaves are on the rails as the wheel slide protection can not fully compensate the effect. The central power module has limits with heat dissipation as well which can lead into situations where the power output needs to be limited which is automatically done in this construction concept.

A Stadler GTW-2/6 DMU train of Proastiakos (Greek: Προαστιακος) in Athens Railway Station

There are diesel propulsion modules with 550 kW (740 hp) (since 2003) with 2 x 375 kW (503 hp) = 750 kW (1,006 hp) power available, and electric propulsion modules with 600 to 1,100 kW (800 to 1,480 hp). IGBT based traction converters together with asynchronous motors are used as drive units. The traction converters are manufactured by ABB at their site in Turgi, Switzerland and the motors by TSA Austria.

By inserting a middle car (also with only one bogie) on one side of the propulsion module, the GTW 2/6 is expanded to GTW 2/8. Instead of the middle car, another drive module can also be inserted. Between the two modules are then either a trailer passenger car (GTW 4/8) or two medium cars and partitions (GTW 4/12). For operational flexibility up to four GTWs of the same pattern can be operated as a multiple unit.

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