Taiwanese rail authorities say the driver of a train that derailed, killing 18 people, failed to report to controllers that he had turned off its control system before the accident.
The express train carrying 366 passengers went off the tracks in the northeastern county of Yilan on Sunday. 190 people were injured.
The damaged tracks were repaired and train services resumed on the tracks on Wednesday morning.
The train was believed to have been travelling at 140 kilometers per hour -- nearly double the speed limit of 75 kilometers per hour -- just before the accident.
The driver admitted that he switched off the automatic control system because of trouble with the power system.
Authorities told reporters on Wednesday that any train driver is required to report to a control center when turning off the safety system.
But they said the driver of the derailed train failed to do so and that controllers were unaware of the fact that it was running with the system turned off.
Referring to the driver's claim of trouble with the power system, the authorities say they confirmed there was something wrong with the air compressor, but that the problem wasn't serious.