How the UK Gas Industry's shared ‘NARMS’ asset health and risk framework uses AIM for smarter, safer and cleaner network investment.
Client:
UK Gas Industry (Cadent, SGN, NGN WWU, NGGT)
Location:
United Kingdom
Consulting Partner:
ICS Consulting, DNVGL, ULC, and Probit
Asset Types:
Gas distribution and transmission mains, stations, valves, meters
AIM Version Used:
AIM 2.0-4.2
Key Outcome:
Sector-wide planning framework for NOMS/NARMS, delivering Ofgem-compliant investment strategies with 15–40% efficiency gains
The UK Gas Industry includes a mix of Gas Distribution Networks (GDNs) such as Cadent Gas, Scotia Gas, Northern Gas, Wales & West Utilities, and the National Grid Gas Transmission (NGGT) system. Together, these organisations manage over 170,000 km of gas pipelines, delivering energy to millions of homes and businesses across the UK.
With ageing infrastructure, health and safety commitments and rising environmental obligations, the industry faces some of the most complex planning challenges in infrastructure today, requiring a collaborative, data-driven approach to strategic asset investment.
The challenge
The sector needed to move beyond traditional investment planning methods, many of which were manual, spreadsheet-based, or siloed, and implement a unified approach to risk, cost, and performance optimisation.
The industry also needed to meet Health & Safety Executive (HSE) mandates for cast iron mains replacement, manage emissions, and adopt a proactive stance on asset reliability, safety, and environmental performance; all while demonstrating transparency and value for money to regulators and the public.
A monetised risk-based methodology and framework, now known as NARM (Network Asset Risk Metric) was developed in AIM to compare asset investment within asset and between assets in a consistent and robust manner.
The framework identifies the potential impact of a networks assets by the assessment of failure, consequence, and the financial cost of failure, allowing risk to be projected forward to determine whole life cost and value of ownership.
Who worked on this project?
DNVGL and ICS Consulting led the development of risk and planning models for the gas sector’s NOMS/NARMS framework, working in collaboration with all 5 gas utilities across the UK.
ICS provided strategic consulting and model configuration services, while Probit supplied the AIM software and technical leadership behind the platform. AIM was deployed at multiple levels, from localised project decision-making through to national-level optimisation and across multiple asset classes.
Probit provided the analytical and architectural foundations that allowed utilities like Cadent and WWU to develop consistent, regulator-approved investment strategies. Other partners, such as ULC Technologies, contributed specialist capabilities including robotic remediation as novel interventions.
How was AIM used?
AIM provided the core digital infrastructure for risk-based investment planning across the UK gas sector. It was configured to provide the blueprint for the industry NARMS methodology:
- Model assets from the ground up, using ‘bottom-up’ data structures to assess individual pipes, components, and site assets, then aggregate results across cohorts, regions, or entire networks.
- Monetise risk by combining failure probabilities (PoF) with consequence models (CoF) across multiple domains, including safety, environmental impact, financial risk, and social cost.
- Support long-term planning, using deterioration modelling, risk discounting and life cycle cost analysis.
- Create and test interventions, with the ability to model cost, benefit, and risk reduction for replacement, refurbishment or other strategies.
- Run optimisation scenarios, balancing multiple objectives and constraints (e.g. budgets, targets, performance levels).
- Visualise outputs via dashboards and risk maps, or export results into reporting tools like Power BI, GIS, and Tableau.
This enabled transparent, auditable decision-making, fully aligned with NARMS and other regulatory standards.
The results
Deployment of AIM across the UK gas sector delivered substantial, quantifiable improvements in investment decision-making:
- Regulatory approvals secured for NARM submissions across GDNs and NGGT, meeting all licence conditions and Ofgem expectations.
- Planning speed dramatically improved, with complex scenario modelling reduced from weeks or months to hours or minutes.
- 15–40% cost savings achieved across multiple applications compared to traditional methods.
- Tactical planning embedded, with utilities like Cadent now generating live annual work programmes directly from AIM models.
These results demonstrate the impact of AIM not just as a planning tool, but also as a strategic asset.
Philippa Wrenn
Asset Planning Manager, Wales and West Utilities
Technical insight
AIM’s foundation for NOMS/NARMS planning is built around monetised risk, calculated by multiplying Probability of Failure (PoF) with Consequence of Failure (CoF) using Health Index models, deterioration curves, and criticality matrices.
Its scenario engine supports stochastic modelling, uncertainty quantification, and optimisation under constraint.
AIM’s model editor allows utilities to create or adapt complex formulae without code, while its Asset Data Manager ensures that data infill, cleansing, and transformation are consistent and transparent.
What followed for the UK Gas Industry and AIM?
AIM was used to update the NARMS methodology in early 2024 and to test and compare against previous versions and across the UK gas industry. This version was rolled out for the GD3 regulatory investment submission.
The configurability of AIM will enable the NARMS methodology to continually adapt and evolve in response to changing regulatory, environmental, and social pressures, from Net Zero and hydrogen transition to customer vulnerability and digitalisation.
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