Urban transport infrastructure
Published On: April 11, 2022

Professor Liz Varga is Professor of Complex Systems at University College London and a Commissioner of the National Preparedness Commission. Here, Professor Varga offers an overview of her work to develop a set of principles or shared goals for national infrastructure resilience, with the United Nations Office for Disaster Risk Reduction.


The UK’s national infrastructure delivers critical services to every part of society, industry, business, and government in different settings, e.g., households, hospitals, manufacturers, and banks. Our economy and way of life rely on critical services which are often taken for granted until they are disrupted. Critical services such as potable water provision, energy networks, transport systems, sewerage systems, and digital communication networks are invisible until they are not functioning as normal, or not available at all.

There is no set of principles or shared goals for national infrastructure resilience and to address this gap, the United Nations Office for Disaster Risk Reduction (UNDRR) supported by University College London (UCL) are developing a set of shared principles. A draft set of 14 Principles for Resilient Infrastructure were identified and shared for expert and practitioner feedback in the UK in 2021 before wider consultation. Following feedback from the consultation workshops the 14 draft principles were refined down to six recommended principles. These have been the subject of further expert review and global consultation and have responded well to robust challenge.

The principles support national scale Net Resilience Gain and the achievements of outcomes and impacts that emerge from increased infrastructure resilience.

Challenges to infrastructure resilience

The range and type of challenges to the resilience of our national infrastructure is growing and this is a cause for concern. These challenges include the way national infrastructure is structured and organised, as well as external and environmental risks, see examples below.

Structural challenges:

  • Proximity: geographical co-location and proximity of networks along service corridors, which is designed to enable efficiency.
  • Integration: interdependencies of networks and systems that are integrated between different sectors, e.g., transport systems distributing fuel and energy for power generation.
  • Vulnerability: single points of failure which could be vulnerable and targeted with attacks designed to cause maximum outages.
  • Asset health: ageing asset portfolios coupled with reduced maintenance regimes leading to increased risk of poor asset health and asset failure.

External and environmental challenges:

  • Supply chains: disruption to global supply chains through e.g., disrupted shipping/freight movements, lack of direct control over external production sites and processes, causing supply delays and interruptions.
  • Public health: significant public health issues, e.g., pandemics, epidemics and infection outbreaks, and the impact on productivity and workforce numbers.
  • Weather events: increasing severity and frequency of weather events e.g., storms, droughts, heat waves, etc. which could lead to human impact being exacerbated by infrastructure construction and operations.
  • Capacity: growing demand for critical services from populations especially in urban areas not being met by growth in critical services provision, which could lead to outages from breaches in network constraints

Infrastructure resilience strategies and aspects

The resilience of infrastructure and critical service provision has become an increasingly important national issue. This is especially in the context of delivering the UK government’s levelling-up agenda, which is aiming to provide widespread reliable and affordable services, such as faster broadband. Strategies for creating infrastructure resilience, and ensuring reliance of the provision of critical services where hazards are present, have generally focussed on four key areas:

  • Redundancy: such as n-1 capacity and other means of continued operation if one or more components fail.
  • Robustness: defending infrastructure from hazards, such as the building of barriers and other layers of security and protection.
  • Reliability: regular, proactive, and preventative maintenance.
  • Recovery: having mechanisms in place to ‘bounce back’ and recover failed operations in a safe and timely manner.

Aspects of resilience capture the range of actions that will deliver resilient infrastructure (see NIC Anticipate, React, Recover)

  • Anticipate: actions, such as data collection, to prepare in advance to respond to shocks and stresses.
  • Resist: actions, taken in advance, to withstand or endure shocks and stresses, such as flood defences.
  • Absorb: actions to lessen impact that cannot be resisted, such as network redundancy
  • Recover: actions to quickly restore expected levels of service following an event,
    such as emergency procedures to restart services.
  • Adapt: actions to modify infrastructure to enable it to continue to deliver services in the
    face of changes, for example using storage capacity.
  • Transform: actions to regenerate and alter infrastructure systems, for example
    transforming infrastructure to meet net zero.

Towards shared principles for infrastructure resilience

Despite the importance of infrastructure resilience and the integrated nature of infrastructure, there is no set of principles or shared goals for national infrastructure resilience. There is also no level of commitment for infrastructure investment to make a positive impact on systemic resilience of infrastructure or to protect the ongoing supply of critical services, i.e., “Net Resilience Gain”.

Developing a set of cohesive shared principles for resilient infrastructure would help decision making at national and regional levels and provide a mechanism for targeting both infrastructure investment and operational changes. This initiative to address the gap in shared principles is led by The United Nations Office for Disaster Risk Reduction (UNDRR) supported by University College London (UCL). The Principles for Resilient Infrastructure provide normative goals and desirable outcomes for systemic resilience of infrastructure to meet the targets of the UN’s Sustainable Development Goals, specifically SDG9 Innovation and Infrastructure; and the Sendai Framework for Disaster Risk Reduction; specifically, Global Target D to substantially reduce disaster damage to critical infrastructure and disruption of basic services.

The principles recognise that ensuring infrastructure resilience is a trans-national issue, not confined to infrastructure organisations. The wider natural environment, society, technology, regulation, finance, and investment, all have an impact. The work on Principles for Resilient Infrastructure highlights the value of taking a systemic perspective, especially the effect on resilience from the dynamics of structural changes to infrastructure. The introduction of new assets and the decommissioning of old or damaged assets, results in changes to systemic resilience, as do changes in skills, abilities, aging of assets, exposure to hazards, etc.


The methodology for developing the Principles for Resilient Infrastructure and identifying key actions for implementation them was informed by academic and practitioner examples and approaches. The first stage involved a review of academic articles and case study literature. This identified 14 draft principles organised into six categories with examples of key actions for implementation, which are described below.

The draft set of 14 principles were shared in 2021 for expert and practitioner feedback in the UK before wider consultation. Key UK institutions involved in different aspects of infrastructure resilience were consulted on the 14 draft principles under Chatham House rules, including commissioners of the National Preparedness Commission (NPC).Following consultation, the 14 draft principles were refined to reflect the feedback received and this resulted in a set of six recommended principles, with key actions for implementation. These have been the subject of further expert review and global consultation. The six principles for resilient infrastructure have responded to robust challenge.

Draft set of 14 principles

Category 1: Socio-Economic Centric

  • Strengthen economic capacity: this can be established through investment in infrastructure resilience This not only provides opportunities to strengthen these systems in the face of shocks and stresses, but it can also have economic benefits for all involved stakeholders. Examples of economic benefits include having a median benefit cost ratio equal to four, a 0.1% increase in GDP for 1% increase in public capital, and circa 18 million more jobs in renewable energy systems globally by 2030.
  • Providing social well-being and development: resilient critical services enhance quality of life, by improving public health, providing distributed equity, providing inclusive access to services, and encouraging public participation. For example, power-line outages can decrease female labour force participation by reducing opportunities in non-agricultural sectors in South Africa, while electrification can free up time, especially for women, and have positive impacts on health through refrigeration and the replacement of polluting kerosene lamps. Empowering women can support resilience of infrastructure systems by active participation in prevention and recovery projects. For example, women in Honduras and India participated in the repair of hundreds of houses, businesses, and public buildings, as part of the recovery following hurricanes and earthquake events.

Category 2: Sustainability

  • Preparedness for long-term risk: Evidence from case studies show the benefits of having a long term approach to risk. For example, Guyana is protecting its critical infrastructure from coastal and inland flooding, which it has identified as its highest priority hazard owing to the outcome of climate projection studies to assess and mitigate vulnerabilities and risks. A wide range of adaptation measures include early-warning infrastructure, introducing building codes for new construction, and upgrading drainage systems.
  • Current operational delivery: Evidence from case studies include applying nature-based solutions, using ecosystem services and natural capital, and protecting against short-term natural disasters. For example, coastal nature-based solutions can mitigate flood and storm damage more effectively than grey infrastructure alone using coral reefs in shorelines to stabilise and protect coastlines, mangrove trees to reduce wave height, and marshes to grow in elevation as sea level rises.
  • Long-term environmental recovery: this can be achieved by demand reduction, reducing waste, undoing past irresilient decisions, and improving legacy infrastructure. For example, based on new regulations in Mongolia, all mining and all development projects are required to provide biodiversity offsets. Similarly, in the UK highways and network rail infrastructures must protect biodiversity.

Category 3: Shared Responsibility:

  • Creating collaborative capabilities: this focusses on the “four Rs” of resilience (robustness, resourcefulness, recovery, and redundancy), and developing a collaborative approach to data, knowledge, and information; with digital infrastructure playing a large role . For example, organisations with common infrastructure interdependencies should be able to identify them and then share data in a standardised way to facilitate more of a system of systems approach to the “four Rs”. This enables progress from a siloed approach to data towards generating shared insights into how to handle a common threat. Sharing knowledge and experience across traditional boundaries can also be in the form of human knowledge. A collaborative approach to engaging with resilience allows systems to learn from each other’s mistakes and have a coordinated response to common hazards and vulnerabilities.
  • Leveraging physical resources: this needs to be possible both in emergency situations and in day-to-day operations, facilitating collaborative management of those needs. In an emergency response situation, leveraging physical resources might mean managing public funds and emergency supplies, or sharing facilities in response to an emergency, e.g., co-ordinating the use of a school hall as a shelter in advance. This is also relevant in a non-emergency context, e.g., South Yorkshire has merged elements of its police and fire services to meet common needs like vehicle repair. Needs have been identified and then physical resources shared to allow both services to reduce their overheads and dedicate more time and money to frontline services.

Category 4: Survivable Systems

  • Flexibility for future needs: this recognises that the demands placed on our infrastructure systems in the future may look very different from those we face today . We need to develop systems with this in mind and incorporate flexibility into all elements of our systems: supply chains, delivery methods and organisational structures. For example, using cloud computing rather than on site data banks to increase potential capacity.
  • Graceful extensibility: this is a relatively new concept recognising that there will always be unexpected surprises that the system has to deal with. In these circumstances the system might have to go beyond its expected boundaries, or the primary purpose for which it might have been designed, in order to absorb the disruption. This quite often involves an element of human discretion. For example, river levees are designed to keep water in, but in a case of unexpectedly heavy flooding, it might be a better systemically to break through one in order to have a controlled release that minimizes damage to infrastructure and life. We can see that this quite often involves a manual override capacity, and so we need to design that into our systems. We should also extend this concept to organisational structures, designing them in a way that can be reconfigured swiftly to respond to an unexpected disruption.

Category 5: Safe

  • System safety: this emphasises redundancy for system safety to raise baseline safety and be able to manage disruption. We encourage design for structure and system safety considering various risks, and design with passive survivability. For example, in order to adapt to sea levels rising, the 100-acre section of Fort Point channel raised the entire base of the infrastructures by approximately 12 feet, rather than trying to prevent sea water from entering the city and creating a resilient development area to serve as an urban waterfront district for the next 200 years.
  • Data safety: this highlights assurance of data safety to create stakeholder trust. In order to achieve this principle, we should build confidence and trust in cyber physical solutions, decision making, and community engagement. For example, UK critical infrastructure operators implement the EU Network and Information Security Directive which requires compliance with four proposed high-level requirements, including (i) organisational structures, policies, processes to govern the security of network and information systems; (ii) proportionate safety measures to protect from cyber-attacks or system failures; (iii) capabilities to ensure effective defences and to detect cyber security events; (iv) capabilities to minimise the impact of any cyber-security incidents. This means improving appropriate safety investment by formulating policies and market-based incentives, and formulating diverse governance, regulation, and controls.

Category 6: Smart

  • Timely knowledge: this involves using smart technology to mitigate concern or uncertainty by increasing the sensing capacity of the system, improving monitoring and maintenance to enhance awareness and achieve early warnings. For example, the New York City Department of Transportation developed a congestion management system ‘Midtown in Motion’ using cameras and microwave sensors and EZ-pass readers to advanced solid state traffic controllers. This congestion measurement system enables city traffic engineers to identify and respond to traffic conditions in real time by remotely adjusting the traffic signal patterns, unplugging bottlenecks, and smoothing the flow of traffic.
  • Systematic learning: this involves achieving effective decision making by offering substitutable solutions, making well-informed decisions, improving resilience of operational performance and optimising the use of resources. The principle is about discovery, insight, and learning. Drones, sensors, and cameras powered with artificial intelligence infused with data and analytical capabilities will be the monitoring tools making decisions for infrastructure maintenance for many companies in the near future. An example is the use of drones for monitoring underground pipelines and creating images of target states over time. Image analytics can detect changes and measure exact defects such as cracks, corrosions, and failures.
  • Timely intervention: this is about the use smart technologies to be able to respond rapidly to disruptions to critical services so that emergency services, governments, and communities achieve the goal of timely intervention. An example is the use of SOS alerts to include the real-time visual information and navigation warning system in times of crisis, to help users best understand what they need to do to stay safe.

Recommended set of six principles

The six recommended principles reflect findings from consultation and feedback with over 100 experts and other global institutions, and these are described below along with key actions for implementation. These have since been presented to various UNDRR platform meetings and groups, and to an international expert group.

Principle Description Key Actions
Principle 1 (P1):  Adaptively Transforming The goal is to adapt and transform to changing needs. This principle recognises that the demands placed on our infrastructure systems in the future may look different from the demands placed on them today.

Developing systems with this in mind encourages us to incorporate flexibility into supply chains, delivery methods, organisational structures, and operational methods.

Key actions for P1 are:

· P1.1 Design safe-to-fail infrastructure.

· P1.2 Create adaptive capacity.

· P1.3 Develop dynamic structures

· P1.4 Enable extensibility.

· P1.5 Allow for human discretion.

· P1.6 Adopt the appropriate level of complexity

Principle 2 (P2):  Environmentally Integrated The goal is to work in a positively integrated way with the natural environment. This principle recognises the importance of avoiding harm to the natural environment (required to avoid feedbacks such as climate change), as well as the opportunities of working with the natural environment in a positive way, such as planting trees to reduce speed of flood water spread.

Environmentally integrated refers to integration with the natural environment to employ natural capital in favour of adding to its value without harming natural ecosystems.

Key actions for P2 are:

· P2.1 Use nature-based solutions.

· P2.2 Integrate ecosystem information.

· P2.3 Minimise environmental harm.

· P2.4 Maintain the natural environment.

Principle 3 (P3): Protected by Design The goal is to design infrastructure that is prepared for hazards. Infrastructure is exposed to various hazards both known and unknown. And the nature of hazards is constantly changing: their amplitude and frequency, multiple hazards, and new hazards.

The best time for investment in readiness for hazards is at the design stage, which must proactively consider potential negative impacts of disturbance events and disasters with natural hazard origin, on the full lifecycle of infrastructure provision. Resilient design will raise system baseline safety to better absorb, accommodate, resist, adapt to, transform, and recover from the effects of ever-increasing hazards by providing infrastructures with foresighted and proactive solutions.

Key actions for P3 are:

· P3.1 Raise essential safety requirements.

· P3.2 Exceed basic requirements for critical components.

· P3.3 Consider complex interdependencies of connected networks.

· P3.4 Embed emergency management.

· P3.5 Use local sustainable resources.

· P3.6 Design for multiple scales.

· P3.7 Commit to maintenance.


Principle 4 (P4): Socially Engaged The goal is to develop active engagement, involvement, and participation with people. Social responsibility is becoming increasingly prominent as an alternative mechanism to prevent and respond to systems failure. Being socially responsible depends on increasing social awareness, taking a more active role, and improving self-management skills, resulting in more consciousness about how our decisions and behaviours can affect others.

It leads to a growing number of mindful individuals acting better to do no harm to society and benefit the whole community. Infrastructure systems are socio-technical systems. Support for the resilience of infrastructure by the community it serves can result in human flourishing which is the fundamental purpose of infrastructure.

Key actions for P4 are:

· P4.1 Inform people about disruptions.

· P4.2 Raise resilience literacy.

· P4.3 Incentivise demand behaviour.

· P4.4 Encourage community participation.


Principle 5 (P5): Shared Responsibility The goal is to share information and expertise for coordinated benefits. In order to move away from the traditional siloed approach to information, a collaborative approach must be encouraged for the sharing of data, knowledge, and expertise.

Organisations with common interdependencies should be able to share data in a standardised way and generate shared insights into how to handle common threats. A cooperative approach to management and planning benefits from diverse knowledge and experience, allowing a coordinated response to shared hazards or vulnerabilities.


Key actions for P5 are:

· P5.1 Harmonise open standards.

· P5.2 Cultivate collaborative management.

· P5.3 Establish shared responsibilities.

· P5.4 Enhance connectivity for information sharing.

· P5.5 Assure data safety to develop trust.

· P5.6 Share risk and return information.


Principle 6 (P6): Continuously Learning The goal is to develop understanding and insight into infrastructure resilience. The internal complexity and external hyperconnectivity of infrastructures make it difficult for stakeholders to clearly grasp the status of resilience in national infrastructure, which undermines the ability of system operators to prevent, contain and recover from outages.

Therefore, it is necessary for planners to actively prepare for the scale of potential hazards that infrastructures may suffer, for operators to sense the dynamic changes in the operating status of infrastructures to detect anomalies rapidly, and for decision makers to learn and continuously devise strategies to optimize the resilience of infrastructures

Key actions for P6 are:

· P6.1 Expose and validate assumptions.

· P6.2 Monitor and intervene appropriately.

· P6.3 Analyse, learn, and formulate improvements.

· P6.4 Stress test.



Conclusions and next steps

The resilience of critical services and national infrastructure has never been more important. There is strong evidence that investment in infrastructure resilience is economically justified. The six recommended principles support national scale Net Resilience Gain and the achievement of outcomes and impacts that emerge from increased infrastructure resilience. The principles are not intended for assessment of individual assets or components of infrastructure. They will be the subject of a global consultation in March 2022 before being finalised. Key actions have been defined for each of the six recommended principles, which will allow them to be developed into stakeholder actions. Global examples are provided for the key actions demonstrating their relevance to emerging, developing, and developed nations. It is recommended to work with global infrastructure organisations to seek their endorsement and to create local opportunities for translation into good practice guidance.

Next steps to develop and measure the usefulness of the principles could involve demonstrators/pilots, an international standard, and/or digital twins and computational models:

  • Digital twins can continuously monitor national infrastructure, providing early warning of potential vulnerabilities especially when linked to meteorological and other geo-physical systems. They can also aid continuous assessment of the national efficacy of these principles and provide timely detection of unintended consequences.
  • Computational models could be used to determine Net Resilience Gain which is expected to emerge as the key actions are adopted into national infrastructure. Existing plans/pipeline for nature infrastructure investment could be assessed before they are commissioned to assure compliance with Net Resilience Gain.

For more details on United Nations work in this area, visit:






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