To redefine limiting distance as being less than actual in cases where the time from receipt of notification of a fire by the fire department until the first fire department vehicle arrives at the building is longer than assumed for the application of requirements based on limiting distance, and where protection is not provided by sprinklers.
This is to limit the probability that fire will spread from the subject building to an adjacent building during the time required for emergency responders to perform their duties, which could lead to damage to the adjacent building.