Risk Assessment & Risk Matrix

Risk Assessment & Risk Matrix

NexusRMS uses a standard 5×5 risk matrix to quantify hazards consistently across all RAMS documents and standalone risk assessments. This methodology aligns with HSE guidance and provides a clear, auditable framework for risk evaluation and control prioritisation.

5×5 Risk Matrix

The risk matrix plots Likelihood against Severity to produce a numerical risk score:

Score	Likelihood	Severity
1	Rare	Negligible
2	Unlikely	Minor
3	Possible	Moderate
4	Likely	Major
5	Almost Certain	Catastrophic

The Risk Score is calculated as Likelihood × Severity, producing a value in the range of 1 to 25.

Risk Levels

Level	Score Range	Colour	Action Required
Low	1–6	Green	Manage by routine procedures
Medium	7–12	Yellow	Specific risk reduction measures required
High	13–19	Orange	Senior management attention; significant controls required
Critical	20–25	Red	Immediate action required; work must not proceed until risk is reduced

Initial vs Residual Risk

Each hazard is assessed twice:

• Initial Risk — the risk score before any control measures are applied; represents the inherent danger of the hazard
• Residual Risk — the risk score after control measures have been implemented; represents the managed risk level

The Risk Reduction metric is calculated as the initial score minus the residual score. This value measures the effectiveness of your control measures. A higher risk reduction indicates more effective mitigation.

Per-Hazard Risk Assessment

Within the RAMS Document Builder, each hazard includes interactive risk assessment controls:

• Likelihood Slider — adjust from 1 (Rare) to 5 (Almost Certain)
• Severity Slider — adjust from 1 (Negligible) to 5 (Catastrophic)
• Real-Time Score — the risk score and level update instantly as sliders are adjusted

Live Risk Summary

The Live Risk Summary component provides a real-time visualisation of the risk matrix across all hazards in the current document. As hazards are added, removed, or reassessed, the summary updates to show the distribution of risks across the matrix.

Standalone Risk Assessments

The system supports standalone formal risk assessments via the RiskAssessment model for assessments outside a specific RAMS document. Standalone assessments include:

• Assessment Name — descriptive title for the assessment
• Location — site or area being assessed
• Date — date the assessment was carried out
• Assessed By / Reviewed By — persons responsible for conducting and reviewing the assessment
• Next Review Date — scheduled date for reassessment

Assessor Qualification Tracking

The system tracks assessor qualifications to ensure competency:

• SMSTS — Site Management Safety Training Scheme
• SSSTS — Site Supervisor Safety Training Scheme
• H&S Qualification — general health and safety certification (e.g. NEBOSH, IOSH)

Control Effectiveness Rating

Each control measure can be rated for effectiveness after implementation:

• Not Assessed — effectiveness has not yet been evaluated
• Ineffective — control does not adequately reduce the risk
• Partially Effective — control provides some risk reduction but gaps remain
• Effective — control adequately reduces the risk to an acceptable level
• Highly Effective — control significantly exceeds the minimum requirement

Database Computed Columns

Risk scores are stored as PostgreSQL computed columns using the storedAs directive. The columns risk_score_before, risk_score_after, and risk_reduction are automatically calculated by the database engine, ensuring consistency and enabling efficient queries and aggregations without application-level computation.