Normal Accident Theory articulates three dangers of redundancy, summarized by Scott Sagan as follows.
- Redundancy increases complexity, generating “common-mode” errors. Example: Fermi Reactor safety device added at last minute breaks off and blocks coolant pipe.
- Redundancy may lead to decreased sense of responsibility among workers. Example: Diffusion of responsibility among AWACS operators led to no one passing needed information to F-15 pilot. See Bystander Effect
- Redundancy may lead to increased production pressures due to perceived safety. Example: Injuries increase when helmets added to a sport.
Examples and breakdown from “Learning from Normal Accidents” (pdf)
Normal Accident Theory see accidents as “normal” and has related insights.
A related issue is Alarm Fatigue
Source: Three Dangers of Redundancy