The Puyuma Express was built by the Japanese manufacturer Nippon Sharyo in 2011 and had undergone major maintenance the year before. By all accounts, it was a modern, well-maintained train. But on that October afternoon, a chain of mechanical issues and human decisions converged. The driver had reported problems with the main air compressor before the derailment. The Taiwan Railways Administration's chief secretary later acknowledged that a full compressor failure could cause deceleration problems but should not, by itself, cause a derailment. The critical factor was something else entirely: the automatic train protection system, or ATP, which monitors speed and applies brakes when a train exceeds limits. The driver had turned it off.

Among the 18 people who died were eight members of the same family. They had boarded the train together on a Sunday trip, and none of them survived the derailment. Taiwan's Railway Authority confirmed the family's loss as rescue operations continued into the evening. By 9:35 that night, all passengers -- living and dead -- had been removed from the wreckage. Hundreds of medics, firefighters, and 100 soldiers responded to the scene. Fifty-three injured passengers remained hospitalized. The derailment was Taiwan's worst rail disaster since a 1991 collision near Miaoli that killed 30 people, a record it held until a 2021 derailment in Hualien killed 49.

Investigators determined that the direct causes were excessive speed in the curve and the driver's decision to disable the ATP system. He had switched it off after passing Fulong station because the malfunctioning air compressors were inhibiting acceleration and causing delays. At subsequent stops in Yilan and Luodong, he did not reactivate it. Without ATP, the train's speed was unmonitored as it approached the fatal curve. The compressor problems, initially suspected as a contributing factor, were ultimately ruled out. But the investigation uncovered something broader: technical flaws in the connection between the Puyuma trains' protection systems and the central signaling network. Nippon Sharyo acknowledged the design flaw and committed to fixing it. Improper management of the ATP testing process led to indictments of two senior TRA officials.

In October 2021, the Yilan District Court sentenced the driver to four years and six months imprisonment for negligent homicide. Two other Taiwan Railways Administration officials were acquitted. But the derailment's most lasting consequence was institutional. Recognizing that Taiwan lacked a comprehensive transportation accident investigation body, the government expanded the Aviation Safety Council -- which had previously handled only air incidents -- into the Taiwan Transportation Safety Board, with jurisdiction over rail, maritime, and aviation accidents alike. President Tsai Ing-wen, who had called the disaster a "major tragedy" and met with victims' families the day after the crash, presided over reforms that fundamentally restructured how Taiwan investigates transportation failures. The curve at Xinma is quiet now. The trains still run. But they run under a system that remembers what it cost to ignore a warning.