Facilities debates door-controller failure behavior versus traffic-signal safety behavior during outages. Which guidance is most appropriate?
Select an answer to reveal the explanation.
Short Explanation
Locks and stoplights do not share one magic failure setting. Security doors often fail closed; life-safety gear may need to fail open or fail safe so people are not trapped or stuck. Match the mode to the risk—security versus safety.
Full Explanation
Failure modes are chosen based on whether confidentiality/integrity of access or human safety dominates. Security door controllers commonly fail closed to deny entry on fault, while safety-critical traffic systems may require fail-safe behaviors that keep people safe during outages. A single always-open or always-closed rule for every system ignores that distinction.