🔗 RTT Facilities — Cross‑System Propagation
Interdependence, Cascades, and Systemic Risk
This document defines how risk, degradation, and failure propagate across facilities systems, rather than remaining confined to a single asset class.
It is grounded in the RTT Facilities Playbook and extends the Facilities‑level Propagation Model by making cross‑system coupling explicit.
1. Purpose#
Modern infrastructure systems are deeply interdependent.
The purpose of this document is to:
- Identify how failures propagate between systems
- Prevent cascading outages through early detection
- Inform intervention prioritization and capital timing
- Support cross‑system governance and coordination
- Preserve public safety and trust during complex events
Cross‑system propagation is treated as a first‑class governance risk.
2. What Is Cross‑System Propagation#
Cross‑system propagation occurs when degradation or failure in one facilities system:
- Disrupts the operation of another system
- Amplifies risk beyond the original failure domain
- Creates delayed or secondary impacts
- Escalates from technical failure to societal impact
Propagation may be immediate or latent.
3. Canonical Facilities Systems#
Facilities systems commonly involved in propagation include:
- Electrical
- Water and wastewater
- Communications
- Transportation
- Public buildings
- Emergency and resilience systems
No system is assumed to be independent.
4. Common Propagation Pathways#
Electrical → Water#
- Power loss disables pumping and treatment
- Water pressure and quality degrade
Electrical → Communications#
- Network outages impair coordination
- Emergency response delayed
Electrical → Transportation#
- Traffic signals fail
- Transit systems disrupted
Water → Public Health#
- Sanitation failures escalate rapidly
- Trust erosion follows
Communications → Emergency Services#
- Dispatch and coordination impaired
- Response effectiveness reduced
These pathways are bidirectional and often compound.
5. Propagation Layers (Revisited)#
Cross‑system propagation operates across layers:
- Asset‑Level — component failure
- Corridor‑Level — spatial clustering
- System‑Level — interdependent services
- Societal‑Level — safety, trust, continuity
Facilities governance must reason across all layers.
6. Stress Amplifiers#
Cross‑system propagation accelerates under:
- Climate events
- Aging infrastructure
- Deferred modernization
- Staffing shortages
- Poor inter‑agency coordination
- Governance fragmentation
Amplifiers are explicitly noted during assessment.
7. Detection & Early Warning#
Cross‑system propagation risk is detected through:
- Drift and harmonics scoring
- Corridor classification
- Historical cascade analysis
- Cross‑system indicators
- Environmental monitoring
Early detection is prioritized over post‑event analysis.
8. Intervention Implications#
When cross‑system propagation risk is identified:
- Facilities‑level governance is invoked
- Intervention class may escalate
- Capital timing may accelerate
- Communication requirements expand
No domain intervenes in isolation when dependencies exist.
9. Relationship to Domain Extensions#
Domain initiatives (e.g., RTT‑AGERI):
- Model propagation within their asset class
- Identify cross‑system dependencies
- Feed results into this Facilities‑level framework
They do not redefine cross‑system logic.
10. Canonical Status#
This document is canonical.
All Facilities domains must reference it when assessing interdependence, cascade risk, and coordinated intervention.