JKOY Class Sm5

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JKOY Class Sm5
The interior of an Sm5 unit.
In service2009–
ManufacturerStadler Rail
Built atBussnang, Switzerland
Family nameFLIRT
ReplacedSm1, Sm2
Number built81
Number in service81
Formation4-car sets
Fleet numbers94 10 2081 001–081
OperatorsVR Group
Lines servedAll Helsinki commuter rail lines
Car body constructionAluminium
Train length75.2 m (246 ft 9 in)
Width3.2 m (10 ft 6 in)
Height4.4 m (14 ft 5 in)
Floor height600 mm (24 in)
Platform height550 mm (22 in)
  • 1 pair of plug doors per motor car
  • 2 pairs of plug doors per trailer car
Wheel diameter
  • 870 mm (34 in) (motorised bogies, new)
  • 800 mm (31 in) (trailer bogies, new)
  • 2,700 mm (8 ft 10 in) (motorised bogies)
  • 2,750 mm (9 ft 0 in) (trailer bogies)
Maximum speed160 km/h (99 mph)
Weight132 t (130 long tons; 146 short tons)
Axle load
  • 20.5 t (20.2 long tons; 22.6 short tons) (motorised bogies)
  • 20.5 t (20.2 long tons; 22.6 short tons) (trailer bogies)
Traction motors4 × TSA TMF 59-39-4 500 kW (670 hp)[1]
Power output2,000 kW (2,700 hp)
TransmissionVoith SZH-595 gearbox
Acceleration1.2 m/s2 (3.9 ft/s2)
Electric system(s)25 kV 50 Hz AC catenary
Current collector(s)Pantograph
UIC classificationBo′2′2′2′Bo′
Safety system(s)ATP-VR/RHK
Coupling systemScharfenberg
Track gauge1,524 mm (5 ft)
Sourced from [2][3][4] except where noted.

The Sm5 electric multiple unit (EMU) is a low-floor train used on the Helsinki commuter rail network. Unlike other train types on the network, the Sm5 units are owned by Pääkaupunkiseudun Junakalusto Oy, a subsidiary of the cities of Helsinki, Espoo, Vantaa and Kauniainen. The units are leased to the Helsinki Regional Transport Authority (HSL), and VR operates them. [5]


Junakalusto Oy ordered 32 Stadler FLIRT EMUs from the Swiss manufacturer Stadler Rail in 2006. The first two units were delivered in November 2008[6] and 2009. The units were put through extensive testing on the Finnish rail network before the first unit entered commercial service in November 2009.[7] As of July 2012, seventeen units have been delivered, all of them being in service. Nine more trainsets were ordered in October 2011 and 34 further units in 2014, raising the total to 75.[8]

The Sm5 units are designed for the Finnish winter conditions. They are fitted with 50–100% thicker thermal insulation compared to previous FLIRT models, and the incoming fresh ventilation air is preheated with the outgoing warm air to recover heat. The entrance areas are fitted with fan heaters in order to preserve the interior climate as passengers enter and leave during cold weather.[9][10]

The Sm5 unit is mostly low-floor with all entrances level with the station platforms. The interior space is open through the articulations so that passengers can walk through all the four cars from end to end. This allows passengers to easily occupy the cars evenly. The wide Finnish loading gauge allows the cars to be wider than most European railway cars. This allows a 2+3 seating configuration in the commuter trains, but still with comfortable spacing.

The Sm5 series is planned to replace the two oldest electric multiple unit series in the Helsinki commuter traffic, the Sm1 and Sm2. The Sm5 are also used for the airport rail service, the Ring Rail Line connecting the Helsinki-Vantaa airport to the rail network, operated since July 2015. At the same time HSL repainted the trains in a distinctive purple to differentiate the capital region commuter trains from the outer suburban services to places like Riihimäki.

The trains are transported from the Swiss factory by road and ferry, since they cannot run on European standard gauge railways.[11]


  1. ^ "Stadler Rail FLIRT EMU for various operators". Traktionssysteme Austria. Retrieved 29 June 2023.
  2. ^ "Low-floor electric multiple unit FLIRT with SZH-595 final drives" (PDF). Voith. Retrieved 29 June 2023.
  3. ^ "Railvolution: The Professional Two-Monthly Magazine Of Rail Transport Worldwide" (PDF). Vol. 11. ABB. Retrieved 29 June 2023. {{cite magazine}}: Cite magazine requires |magazine= (help)
  4. ^ "Electric low-floor multiple unit FLIRT" (PDF). Stadler Rail. Retrieved 29 June 2023.
  5. ^ "Electric low-floor multiple unit FLIRT: Sm5 trains for Junakalusto Oy, Finland" (PDF). Stadler Rail. Archived from the original (PDF) on 27 July 2011. Retrieved 12 November 2008.
  6. ^ "Sm5-juna tuli Suomeen" (PDF). Rautatietekniikka (4). Rautatiealan Teknisten Liitto RTL ry: 26. 2008. ISSN 1237-1513.[permanent dead link]
  7. ^ "Uusi kaupunkijuna liikenteeseen" (in Finnish). Pääkaupunkiseudun Junakalusto Oy. 13 November 2009. Archived from the original on 7 March 2010. Retrieved 20 November 2009.
  8. ^ "34 new Flirt trains for commuter train services". Helsingin Seudun Liikenne. 12 September 2014. Retrieved 7 December 2014.
  9. ^ "Hot FLIRT in the cold north" (Press release). Stadler. November 18, 2009.
  10. ^ Stadler. "Electric low-floor multiple unit FLIRT - Sm5 trains for Junakalusto Oy, Finland" (PDF). Archived from the original (PDF) on 2009-11-27. Retrieved 2009-12-02.
  11. ^ "Ohne Drehgestelle nach Finnland". 26 February 2011. Retrieved 2 June 2011.

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