[LargoLasskhyfv]

That accident happened long ago, on a testing track, due to bad signalling/communications, leading to maintenance equipment still on the tracks, and the maglev running into that.

https://en.wikipedia.org/wiki/Lathen_train_collision

The slowing of this https://en.wikipedia.org/wiki/Shanghai_maglev_train is caused more by economical factors like ridership and electricity costs.