To limit the probability that excessive variance
in the configuration of a stair will excessively disrupt the gait
of users, which could lead to:
- persons misstepping and tripping, or
- persons misstepping and tripping in an emergency --
when traffic flow is expected to be limited owing to the presence
of exit stairs as an alternate option or to the limited number of
occupants in dwelling units -- which could lead to delays in the evacuation
or movement of persons to a safe place.
This is to limit the probability of
harm to persons.