X2 is the Swedish high speed train system operated by the operator SJ (Swedish Railways) under the SJ 2000 brand name. It has a top commercial speed of 200 km/h (120 mph), but has reached 276 km/h (171 mph) in a test. The reason the X2 was chosen was that Sweden (like most other countries) has very curved railways, and not enough traffic to justify building special high-speed railway lines (at least before 1990). As a result, a Swedish tilting train had to be developed.