Infrastructure Interdependencies Research Approach

Dana Brechwald, Earthquake and Hazards Specialist

Lifeline Committee Meeting

July 26, 2012

Types of Interdependencies(Chang et al 2006)

• Physical – one system depends on another for operation (ex, wastewater depends on power)

• Geographic – co-located systems• Cyber – linked electronically or through

information-sharing• Logical – other, such as shared financial market

Types of Interdependent Failures(Chang et al 2006)

• Cascading – direct disruption• Escalating – exacerbates already-existing

disruption, increasing severity or prolonging• Restoration – impacts the restoration of another

system• Compound damage propagation – leads to

disruption that causes serious damage• Substitutive – disruption due to excessive

demands placed on a system to substitute for failed system

Example:

Upstream and Downstream

Interdependencies

Describing Characteristics of Interdependent Failures (Chang et al 2006)

• What is the initiating event?• What is the spatial extent?• What is the duration of the failure?• What are the impacted systems and subsystems?• Is the interdependency expected (linear) or

unplanned/unexpected (complex)?• Is there feedback from the secondary system back to the

initial system?• What was the operational state of the system before it

failed?• What is the adaptive capacity of the system(s)?• What is the restoration time?

Characteristics of Interdependencies Consequences (Chang et al 2006)

• What is the severity of the consequence?• What type of consequence is it? Economic,

public health and safety, social, environmental, etc

• What is the spatial extent of the consequence?

• How many people are impacted?• What is the duration of the consequences?

(Rinaldi et al 2001)

Objectives for Our Study• Goal: Understand performance of infrastructure systems serving

airports to better understand performance of airports• Objectives

– Identify interdependencies– Qualify interdependencies– Understand vulnerabilities due to interdependencies– Find “choke points”– Find redundancies and “islands”– Project consequences– Identify and prioritize key mitigation strategies– Facilitate conversation among key stakeholders– Better understand how consequences will affect restoration and recovery

• Are these the right objectives? Should anything be added/changed/removed?

Scope of Our Study• Systems

– Power– Water and Wastewater– Communications– Transportation– Jet Fuel

• Size– Region – high level– Airport-specific – more detail

• Is this the right scope? What level of detail should we aim for at each level? Are there any other systems we should look at?

Case Studies

• Don’t Wing It case studies (Perkins, 2000)– 1989 Loma Prieta– 1994 Northridge– 1995 Kobe– 1999 Turkey– 1999 Taiwan

• Should we do case studies?• Should we add/change/remove from this list?

Quantitative Approaches• Many models are being developed to anticipate potential

interdependencies• Use algorithms to examine:

– Given a set of initiating events, what is the cascading impact on a subset of nodes?

– Given a set of nodes and a desired end state, what is a set of events that would cause this effect?

– Given a set of events and a set of observed outcomes on nodes, is it possible to determine derived interdependencies?

– Given a set of infrastructure networks and a critical function, what is the subset of critical nodes that will adversely impact a specific functionality due to a dependency?

• Require high level of specific data, expertise• Not clear how outputs relate to multiple sector

consequences

Modeling Interdependent Systems

(Pederson et al, 2006)

Qualitative Approaches

• Rely on empirical observation, expert interviews

• Typically use a damage scenario• Examine whole systems, not just nodes• Look at multi-sectoral societal impacts• Wide variety of outputs

(Pederson et al, 2006)

(AIDRC, UBC)

AIDRC

Analyzing Infrastructures for Disaster Resilient Communities (AIDRC)• Bases study in earthquake damage scenario• Conducts interviews

– Verify scenario– Characterize vulnerabilities and interdependencies– Estimate the ability of infrastructures to withstand and

recover from extreme events– Create diagrams based on data gathered from interviews

• Conducts Workshop– Review interdependencies and vulnerabilities identified

in interviews– Ranked and prioritized mitigation strategies

AIDRC

AIDRC

San Francisco Lifelines Council• Scenario-based study – repeat of 1906 (consistent with

other studies done in SF)• Emphasis on response and restoration preparedness and

coordination and development of performance standards• Working groups develop questions for infrastructure

operators on system performance, upstream and downstream interdependencies, and preparedness and coordination strategies/issues

• Synthesize data and conduct interviews/workshop to evaluate responses

• Prepare more detailed scenario based on responses• Draft performance standards and preparedness and

coordination strategies

Our Potential Approach

• Take cues from AIDRC and SF Lifelines Council

• Add high-level mapping of systems• Craft interview questions and conduct

interviews• Synthesize data• Confirm data• Any other thoughts and ideas?

Questions

• What do we like about these approaches, and what should we use from them?

• Should we use a scenario, and if so, what should it be?

• How can we improve upon these?• To what extent to we align with SF Lifelines

Council approach?• What is the right approach for us?

Potential Issues and Needs

• May have difficulty gaining access to data• Need to know the right people to contact• Don’t want to duplicate efforts of SF• How can we find the right people to access?