Some modern top rail monorails do it like that: https://commons.wikimedia.org/wiki/Category:Sh%C5%8Dnan_Monorail#/media/File:MonorailShonan.JPG https://commons.

Some modern top rail monorails do it like that: https://commons.wikimedia.org/wiki/Category:Sh%C5%8Dnan_Monorail#/media/File:MonorailShonan.JPG https://commons.wikimedia.org/wiki/Category:Sh%C5%8Dnan_Mono... The rails is a steel girder with two raceways around a slot inside. The cars hang from T-shaped boogies that come in via the slot and ride on rubber wheels on the raceways.