NSB Class 73

NSB Class 73 (Norwegian: NSB-type 73) is a class of 22 electric multiple units built by Adtranz for the Norwegian State Railways. The four-car trains were modifications of Class 71, which was again based on the Swedish X2. The A-series consists of 16 intercity trains; they were delivered in 1999 and 2000 and are used on the Bergen, Dovre and Sørland Lines. The intercity service was branded as Signatur until 2003. The B-series consists of six regional trains delivered in 2002 and used on the Østfold Line. The regional trains were originally part of the Agenda concept. The trains have a power output of 2,646 kilowatts (3,548 hp) and a maximum speed of 210 km/h (130 mph). They have an overall length of 108 meters (354 ft) and have a capacity for 208 seated passengers in the A-series and 250 in the B-series. The trains have a tilting mechanism allowing for faster travel through curves.

The trains were delivered late, and were put into service after the Norwegian Railway Inspectorate had given dispensation from parts of the safety regulation. On 17 June 2000, a train derailed at Nelaug Station after an axle broke. The class was grounded for a month, and the investigation showed both design errors, and lack of proper inspection and testing. After they were put back into service, they were not allowed to use the tilting mechanism—thus not being allowed to run faster than their predecessors. The construction was reinforced, and in 2004, the tilting mechanism was re-enabled along with higher speeds. In 2007, a train derailed on the Bergen Line, and questions were raised about the trains' ability to operate in snow, however the accident report showed that the trains' front axle load was just as able to cope with heavy snow conditions as the locomotives running on the line, and that the derailment would have been more severe if the same conditions would hit a normal train with less secure connections between carriages. On 16 June 2011, two units were destroyed when the train ran into a fire in a snow tunnel at Hallingskeid Station.

Class 73 is a four-car electric multiple unit built by Adtranz. Each four-car train has eight bogies—of which three are powered—with a total power output of 2,646 kW (3,548 hp). The trains have active tilting, which allows speeds 20 to 30 percent higher than conventional trains through curves on conventional lines. Maximum permitted speed is 210 km/h (130 mph). A four-car train is 108.48 meters (355.9 ft) long; an A-series weighs 215.1 tonnes (211.7 long tons; 237.1 short tons) while a B-series unit weighs 216.1 tonnes (212.7 long tons; 238.2 short tons). The trains have a steel body and the entire cabin is pressurized. Rail brakes are installed on all carrying bogies.

The A-series has a capacity of 207 seated passengers, while the B-series has room for 250. The difference is due to the B-series having a smaller bistro and more compact seating. In the A-series, each of the four cars has seating in a different color (blue in BFM73 car, green in BMU73, red in BFR73, and yellow leather in BM73 and in the bistro area in BFR73). Originally, three of the cars had floors with carpet, while the fourth car (BFM73) had vinyl, of consideration to people with allergies. The carpets were removed in about 2005 as it was difficult to keep them clean. Seating is in two classes, standard and Komfort (originally "Plus"); the latter (BM73 car) with leather seating and power supply for laptops. All the cars have cherry tree wood interior. The trains are equipped with a dining section (BFR73 car) and warm meals can be served at the seat or in the diner. The menu is according to the time of day, with breakfasts in the morning and larger meals in the afternoon and evening. The trains also feature a family section with a play area and HC area (BFM73 car). The BFM73 car has also a bicycle room behind the driver's cab. From 2011, the trains are equipped with free wireless Internet.

In 1990 and 1994, NSB published two reports regarding the future of intercity rail transport in Norway. The reports concluded that there would have to be invested 56 billion Norwegian krone (NOK) in new infrastructure if the main corridors were to be built as high-speed railways. Instead, the use of tilting technology was proposed to allow higher speeds on existing lines. In 1992, the Parliament of Norway voted to build Oslo Airport, Gardermoen and connect it to the capital with the high-speed Gardermoen Line. It was decided that the service should take 19 minutes—and not one minute more. When issuing invitations to tenders, NSB specified this time limit as a criterion, which was also the reason the line was dimensioned for 210 km/h (130 mph).

Proposals had been made for NSB to purchase the same units as the Swedish State Railways (SJ), the X2, in a Nordic cooperation to use the same trains in Norway, Sweden and Denmark, but the idea was abandoned. In 1994, NSB launched plans to build 200 kilometers (120 mi) of high-speed railways by 2011, but also these plans were shelved. In May 1995, Osmund Ueland was hired as director-general of NSB, and he scrapped all plans to build new railways, and instead decided to focus on tilting technology.

Class 71 and 73 are based on the Swedish X2, built by Kalmar Verkstad (KVAB) for the Swedish State Railways, and introduced in 1990. Carbody is built of stainless steel. Forty-three units were delivered by 1997; they each considered of a locomotive and two to five unpowered carriages, including a driving trailer. The locomotives had a power output of 3,260 kW (4,370 hp) and a top speed of 200 km/h (125 mph). Compared to X2, Class 73 has an upgraded bogie construction and motors in multiple cars instead of having a locomotive unit. The latter forces a four-car configuration, but allows for better traction and better use of space and weight by placing the technical equipment throughout all four cars.

In 1993, NSB test-ran an X2 train on the Randsfjord Line, and between 29 September and 21 December 1996, ran a unit in regular service on the Sørland Line. On 23 February 1995, NSB signed a contract to purchase 16 Class 71 trains for use on the Airport Express Train on the Gardermoen Line. The contract included two options, one for 16 trains for intercity traffic and one for 6 trains for regional traffic. The reason for using the same type of train as the Airport Express Train, was to reduce maintenance and operation costs through having a unified fleet. The options would only modify the trains slightly; they were primarily designed for the airport service and any optimization for intercity and tilting technology was secondary in the design process. The first option was taken out on 5 March 1997.