This Japanese roller coaster can reach 112 mph in just over 1½ seconds. Now officials are questioning whether what is known as the world’s fastest-accelerating coaster might be fracturing riders’ bones.

Do-Dodonpa, which runs at “super death” speed, according to Fuji-Q Highland Park, was shut down after four passengers reported suffering back and neck fractures after riding it.

CNN reported that the regional government in Yamanashi prefecture said the four injuries were significant and included cervical and thoracic spine fractures.

The likelihood of being seriously injured on an amusement-park ride is 1 in every 15.5 million rides taken, the International Association of Amusement Parks and Attractions estimated in 2019. This summer, a metal plate fell off an Ohio coaster and hit a woman in the head. Two people have died after incidents on an Iowa park’s boat ride over the past five years. In June, an Ohio woman died after the force of a roller coaster severed her artery, which led to severe internal bleeding, the Evansville Courier & Press reported. That ride’s peak speed was 67 mph.

Do-Dodonpa, which loops in front of Mount Fuji, was unveiled in Japan’s Fuji-Q Highland amusement park about 20 years ago and was renovated in 2017.

People who reported injuries rode the roller coaster between December and this month, according to a translated statement from the park. The ride was closed for investigation beginning Aug. 12 and has not reopened.

Kotaro Nagasaki, Yamanashi’s governor, criticized operators of Fuji-Q Highland for not alerting the government to the injuries sooner or adding additional safety precautions to the ride, the New York Times thoracic.

“If they had reported them earlier and taken appropriate actions, some accidents could have been prevented,” Nagasaki said at a Friday news conference.

In the statement, the park extended its sympathies to the injured customers and vowed to investigate the reported injuries under governmental guidance.

Fuji-Q Highland Park grabbed headlines after reopening last summer following a pandemic-related closure and encouraging parkgoers to “please scream inside your heart” to reduce the spread of the novel coronavirus, which causes covid-19. A promotional video for the quiet-rides campaign showed two masked people sitting stoically as the roller coaster they rode climbed to its peak and then sped along its track.

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