Adaptation of existing underground facilities for civil protection purposes – technical barriers and design options

In view of the growing importance of infrastructure resilience and the need to increase public safety, the possibility of using existing underground facilities as temporary shelters is being increasingly analyzed. The paper will address the issue of adapting tunnels, infrastructure facilities, and historic underground excavations for protective functions.

Key technical and design barriers will be discussed, including: space limitations, enclosure tightness, evacuation requirements, and the safe duration of human exposure to conditions of limited air exchange. Particular attention will be paid to ventilation issues and the differences between residential ventilation, fire ventilation, and systems enabling temporary isolation of underground spaces, taking into account the CO₂/O₂ balance and scenarios involving human presence.

The paper will also present the functional differences between a classic civil defense shelter and a temporary shelter, indicating the real possibilities and limitations of adapting the existing underground infrastructure. The presented conclusions may serve as a starting point for developing design standards for future infrastructure investments, taking into account the potential for converting the functions of buildings.