HKL Class M100

The HKL Class M100 is the first and oldest class of metro trains in use on the Helsinki Metro. One train consists of two individually numbered cars. A total of 42 units (84 cars in total) were manufactured between 1977 and 1984.[5]

HKL Class M100
A refurbished M100 train, July 2011
Interior of a M100 carriage
Manufacturer	Valmet, Strömberg
Assembly	Tampere, Finland
Constructed	1977–1984
Entered service	1982
Refurbished	Talgo Oy Otanmäki 2004–2009 VR FleetCare 2019–2023
Scrapped	2021 (prototype "Nokkajuna" units)
Number built	42 units
Number in service	39 units
Number preserved	1 car[1]
Number scrapped	5 cars
Predecessor	"Nokkajuna" (1977 prototype)
Successor	M300
Formation	2 cars
Fleet numbers	101–184
Capacity	118 seats, 130 seats (before second refurbishment)
Operator(s)	Helsinki City Transport
Depot(s)	Roihupelto, Sammalvuori[2]
Line(s) served	Helsinki Metro: M1, M2
Specifications
Train length	44.2 m (145 ft 3⁄16 in)
Car length	22.1 m (72 ft 6+1⁄16 in)
Width	3.2 m (10 ft 6 in)
Height	3.6 m (11 ft 9+3⁄4 in)
Doors	3 double doors per car
Wheel diameter	840 mm (33 in)
Wheelbase	2,200 mm (7 ft 2+5⁄8 in)
Maximum speed	100 km/h (62 mph) (design) 80 km/h (50 mph) (service)
Traction system	Strömberg SCRS–VVVF[3]
Traction motors	8 × Strömberg HXUR/E 505G2 125 kW (168 hp) asynchronous 3-phase AC
Power output	1 MW (1,300 hp)
Electric system(s)	750 V DC third rail
UIC classification	Bo′Bo′+Bo′Bo′
Multiple working	Mechanically with all Helsinki Metro rolling stock
Track gauge	1,522 mm (4 ft 11+29⁄32 in)[4]

Up to six pairs can be combined into a 12-car train formation, however due to the relatively short length of the platforms (especially on the new Länsimetro extension), at most only two pairs (giving a 4-car formation per train; and prior to the Länsimetro opening in 2017 three pairs resulting in 6-car formations could also be seen during rush hour) can be combined for passenger service. Longer combinations are used in maintenance operations. Any Helsinki metro train types can be combined mechanically, such as for towing. The M100 series is the first train in the world to use VVVF propulsion inverters, developed and manufactured by Strömberg.[3]

The first three units (cars 101–106; nicknamed "nokkajuna", "beak trains") were constructed as prototypes in 1977 and had some minor technical differences compared to the later units. The prototype units were retired from service in 2021 and five of them were subsequently scrapped in Vantaa, with one unit preserved at the Helsinki City Museum.[1]

The M100s were refurbished twice: first in 2004–2009, at the Talgo Oy (now Škoda Transtech) rolling stock works at Otanmäki and secondly in 2019-2022 by VR FleetCare at its Ilmala depot,[6][7] to extend their lifetime until their planned retirement in 2030, by which time the class will be almost 50 years old.