In the late nineties, private Swedish train operators needed a modern type of electric multiple units. So Adtranz, later Bombardier developed the Regina that made use of the wider Swedish loading gauge. So it has a body width of 3,450 mm, what allowed to mount five seats abreast. At first, the sets either had two cars with six powered axles or three cars with eight powered axles. Depending on the customer, they were approved for 180 or 200 km/h and are being designated X50 to X54. In 2002, an X52 set a Swedish speed record with 303 km/h. Later also the SJ ordered the Regina, but in a four-car long-distance variant with only four seats abreast that is being called X55. It has twelve traction motors and is known for consuming less power per passenger than the X2. A variant of the Regina was sold to China and is called CRH1.