the weekends; while NSB had previously run trains with 400 to 500 seats, Class 73 had considerably less capacity. Additional services were introduced on the Dovre Line from 11 June 2000, while the introduction on the Bergen Line was delayed because the infrastructure upgrades on the Bergen Line were not yet completed. Axle faults On 17 June 2000, a Class 73 train derailed at Nelaug Station on the Sørland Line. The train was traveling at slow speed and no-one was injured, but had the derailment happened at full speed, it could have been fatal. The derailment was caused by a fatigue failure in the front axle of the train. All Class 71 and 73 trains were immediately grounded, and were investigated by maintenance crews. The derailed train had recently had its axle checked for fatigue, but no cracks had been found. On 19 June, NSB stated that they had made insufficient tests during the controls. Class 71 had been through ultrasonic testing and were therefore allowed to resume operation the day after the accident. A DNV report from late August concluded with that the cracks had been caused by rust, which was again caused by water being sealed in by the corrosion-protective layer. On 23 June, Quale stated that the inspectorate should never have approved the trains. He stated that the Sørland Line was extreme in Europe in the number of curves, and that this gave increased stress on the axles. The tests which were used to approve the trains had been done on the Dovre Line and with a Class 71 set equipped with tilting technology, a class which weighs less than Class 73. He further stated that NSB had controlled only part of the axle and that if proper tests had been made, the fatigue would have been discovered. NSB stated that they had tested the trains on a section of the Dovre Line they considered to be more curvy than the most curvy parts of the Sørland Line. There was also a misunderstanding in the approval, as NSB had said to DNV that the tests on the Dovre Line were not to be considered representative for the Sørland Line, while the inspectorate had the impression that DNV had approved the tests also for the Sørland Line. NSB stated that all tests would be done again before the trains were put back into service. NSB stated that they