Redundancy is not duplication everywhere
Cities prioritize alternatives where consequences of failure are high.
Network loops can help
Some utility and transport networks can route around a failed segment when the design allows it.
Operational redundancy matters too
Backup crews, alternate facilities and mutual-aid arrangements can complement physical redundancy.
Redundancy has cost
Extra capacity requires capital, land, maintenance and management, so resilience is a trade-off rather than unlimited duplication.
Scope boundary. This page explains system relationships at a planning level. Real utility, transportation, emergency, structural, electrical, cybersecurity and public-safety decisions require local agencies and qualified professionals.