What type of support is utilized temporarily when digging infringes upon another structure?

The correct answer is temporary support. This type of support is employed specifically in situations where excavation activities may disturb or threaten the stability of an adjacent structure. When digging occurs close to existing foundations or other structural elements, temporary support systems are installed to provide necessary stabilization and safety measures.

Temporary support allows for ongoing work while ensuring that the surrounding structures remain secure. Examples of temporary support methods include shoring or bracing systems, which are designed to be removed once the excavation is complete and any construction needed to stabilize the site is finished.

In contrast, permanent support would be intended for long-term use, which is not suitable when the need is strictly for the duration of a construction process. Vertical and flexible supports can be various forms of structural reinforcement but do not specifically communicate the transient nature required in this context. Thus, recognizing the necessity and purpose of temporary support is crucial for safe and effective construction practices when working near existing structures.