Say 30 exposed crowded,2 persons per step equals around 4200 kgs, I don't think the stop would be instantaneous.
As for walkways,from memory, max weight per floor plate is 300kgs
Many years ago I was involved in a full load emergency stop test on an escalator,(a simulated broken drive chain where the normal power off apply brake was overidden ) the escalator slid 1.5 steps before stopping.