To limit the probability that, during construction, the sides of the unsupported excavation will not be stable, which could lead to the collapse of the excavation, which could lead to harm to persons.
To direct Code users to the requirements of Articles 4.2.5.1. and 4.2.5.2. with respect to design and construction of unsupported excavations.
To exempt unsupported excavations from the requirements of Sentence 4.2.5.3.(1).