The line ran along the coast between Comodoro Rivadavia and the seaside resort of Rada Tilly, a branch of the Comodoro Rivadavia Railway then operated by Ferrocarriles Argentinos. Its narrow-gauge motor coaches were nicknamed chanchitas, little pigs, half in affection and half in complaint, for their squat shape and uncomfortable ride. In the heat of mid-February, with the beaches full and Carnival approaching, demand far outran capacity. Coach No. 52 pulled away from Rada Tilly that afternoon packed well beyond its limit, every seat taken and people standing wherever they could fit. Most aboard were families and vacationers, ordinary people doing the most ordinary thing imaginable: heading home at the end of a good summer day.

The combination proved fatal. The car was traveling fast, reportedly near 80 kilometers per hour, far too many people aboard, on an unstable narrow-gauge line that hugged the coastal slope. When the railcar left the rails it had nothing beneath it but the drop, and it fell roughly forty meters down the hillside toward the shore. The coach was all but destroyed. Survivors were thrown clear or trapped in the wreckage. These were not statistics but neighbors, children, parents, and friends, people whose summer afternoon ended in the worst way on the rocks below the line. The grief that followed ran through every part of a city where almost everyone knew someone who had been on that train.

Help was organized at once, but the geography fought the rescuers as hard as the clock did. The steepness of the slope where the car had fallen made simply reaching the victims dangerous and slow, and every minute counted for the injured. Among the dead and the survivors were whole families, and the stories that came down through the decades include love stories cut short on those rails, the kind of intimate loss that turns a single afternoon into a permanent mark on a community. Word of the disaster spread fast through Comodoro, and the carnival that was meant to fill the streets that night turned to mourning instead. In a city built by oil workers and immigrants who had come to the edge of Patagonia to make new lives, the tragedy of the chanchita became a shared wound, carried in family memory long after the wreckage was cleared from the beach.

The railway kept running for another quarter century, but its days were numbered. In 1977, Argentina's military government issued a decree closing many rail services it judged unprofitable, the Comodoro Rivadavia Railway among them. The last train reached Comodoro Rivadavia in January 1978, and a 1993 decree under President Carlos Menem confirmed the closure for good. This was not the line's only catastrophe, either; a second, separate rail disaster struck Comodoro Rivadavia in 1960, compounding the city's long, hard relationship with the trains that once knit it together. The tracks are gone now, but the city has not let the dead of 1953 vanish with them. Comodoro has held public commemorations for the victims of the crash, gathering to remember them decades on, so that the people who boarded that little train, expecting nothing more than a ride home, are remembered as the human beings they were.