YONAGO, Tottori >> The Yakumo express trains, notorious for plaguing passengers with motion sickness due to their considerable tilt on curved tracks, will launch a new type of car this spring to improve the ride.

Yakumo, operated by West Japan Railway Co., makes 15 round trips a day between the Okayama and Izumoshi stations in western Tottori prefecture.

The trains, introduced in 1982, are designed to travel through curves without slowing down by tilting inward to suppress the centrifugal force. This causes a wide, slow shaking side to side, especially when the train travels at high speed on a sequence of tight curves. Passengers often feel ill because of the constant tilting and swinging.

The train has garnered the unflattering nickname Guttari Yakumo (weary Yakumo), a pun on Yuttari Yakumo (roomy Yakumo), the name of trains with wider seats.

The system on the new cars minimizes swinging using data on curves and sensors that address the train’s position.

JR West will introduce 44 new cars, four cars for each train. “We are confident that passengers will no longer get train-sick,” said a JR West spokesperson.