Resilience Engineering Research Group

 Next Generation Methodologies and Tools for System Safety Analysis

NxGen final

The NxGen Project

Creating a new modelling framework for complex system safety analysis


Modern engineering systems are rapidly increasing in size and complexity, posing greater safety and risk management challenges than ever before. In addition to this, the threats to these engineering systems are constantly changing and new hazards emerging:

Modern Engineering System Features

  • An increased use of new technologies
  • Operational regimes which restrict the opportunity for maintenance
  • Operation of an engineering system beyond its planned design lifetime
  • An increased exploitation of condition based maintenance
  • The use of complex, phased maintenance strategies
  • Use of autonomy

System Threats

  • Component failure
  • Human error
  • Natural disasters
  • Extreme weather conditions
  • Climate Change
  • Terrorism     
  • Cyber attacks                  

Safety and risk modelling strategies need to adapt to keep pace with these changes and evolving threats, whilst continuing to demonstrate the ability to operate a system or facility safely and with effective hazard control. 

The Project

The foundations of current risk assessment tools and methodologies for safety critical systems were established in the 1970s. Research has made considerable advances in the capabilities of analytical techniques since then. In addition, technology has advanced and system designs, their operation conditions and maintenance strategies, are now significantly different to the types of systems that existed 50 years ago.

The challenge of this 5 year project is to account for all of these factors in developing a single methodology appropriate to meet the demands of modern industrial systems and to implement this in a software tool that has the potential for wide distribution and impact. The tool, accompanied by comprehensive documentation, could be adapted by users to reflect the needs of their system assessment.

This project is funded by the Lloyd's Register Foundation, an independent global charity that helps to protect life and property at sea, on land, and in the air, by supporting high quality research, accelerating technology to application and through education and public outreach. The Lloyd's Register Foundation mission: engineering a safer world, helps reduce risk and enhance the safety of the critical infrastructure that modern society relies upon in areas such as energy, transport and food. 


The objective of the research is to produce a new, generic, approach to system failure modelling which will enhance the traditional, currently used risk analysis methods: Event Tree Analysis and Fault Tree Analysis, both of which have limitations in terms of their applicability to modern systems. The approaches developed will introduce features which can more accurately model the complexity of the industrial systems our society relies upon today.

As a consequence of employing the new tools it is expected that the quality of decisions made to control the risks associated with the operation of hazardous systems and infrastructure will improve and there will be:

  • A reduced risk of fatalities to the public and workforce
  • Reduced risk of incidents which  cause damage to infrastructure
  • A reduced risk of environmental pollution
  • Optimising the most cost effective use of limited resources available
  • Increased productivity
  • Increased knowledge in the community 

NxGen Key Information:

Duration: 5 years

Funder: Lloyd's Register Foundation

Project Lead: Prof John Andrews

Academic Collaborators: Prof Ali Mosleh (UCLA), Prof Antoine Rauzy (NTNU)

Industrial Case Study Partners: Rolls Royce (aerospace and nuclear), High Speed 1 (HS1), Rail Safety and Standards Board (RSSB)


  Proposed key features of the new methodology

  • Component failure and repair times represented by any distribution
  • The ability to account for dependencies between component failure events
  • The ability to model complex asset management strategies
  • Representation of the full range of component failure modes and degraded states
  • Phased maintenance periods
  • Incident dynamics
  • Modelling journeys (phased missions) in addition to system lifetimes
  • Incorporation of resilience concepts 
  • Integration of the stochastic failure processes with the deterministic models of the engineering system performance
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  For more information on the project contact Professor John Andrews

Resilience Engineering Research Group

The University of Nottingham
Pavement Research Building
University Park
Nottingham, NG7 2RD

telephone: +44 (0)115 84 67366