The reason this was used in Wuppertal is that because the town is a steep valley with a river in the middle, so the best/only place to hang the track was over t

The reason this was used in Wuppertal is that because the town is a steep valley with a river in the middle, so the best/only place to hang the track was over the river. Wikipedia has the (not very long) full list of every "dangle-train" ever built: https://en.wikipedia.org/wiki/Suspension_railway https://en.wikipedia.org/wiki/Suspension_railway