The underworld is made up of four vestibules and three hells properly so called.
To remedy these defects vestibules were introduced, to enclose the platform with a housing so arranged as to be continuous when the cars are made up into trains, and fitted with side doors for ingress and egress when the trains are standing.
The application of vestibules is practically limited to trains making long journeys, as it is an obstruction to the free ingress and egress of passengers on local trains that make frequent stops.
The vestibules have each two rulers, Zartay and Zartanay, Hag and Mag, Gaf and Gafan, Anatan and Kin.
In the vestibules dirty water is still to be met with, but the hells are full of scorching consuming fire, except Krun's domain, where is nought but dust, ashes and vacancy.