Understanding Resiliency

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UnderstandingResiliency Vulnerabilityin
Transport Network Design
Ideas Network Ltd applied imagination
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An intuitive understanding of resiliency
Two basic units of diversity the Cycle the
Shared Edge
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Creating a graphical representation of diversity
Level 0 Physical Topology Level 1 Diversity
in Level 0
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Applying the process recursively
Level 1
Level 1 Diversity in Level 0 Level 2
Diversity in Level 1
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Representing a networks inherent diversity

• Two basic units of diversity in bi-directional
  networks the Cycle the Shared Edge.
• Each of the units are abstracted to form a
  bi-partite graphical representation of the
  inherent diversity.
• The process of abstraction is repeated
  recursively until a level is reached where
  there is no inherent diversity.
• Level 0 represents the physical topology of the
  network, Level n (gt0) represents the diversity
  inherent in Level n-1
• In this way, we can create an 3D graphical
  representation of the full depth of diversity
  inherent in complex networks.

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A portion of the Netherlands rail network
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The A3 network analysis tool
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Level 0 of the main rail network (aprox)
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Levels 1 2 of the rail network
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Levels 0, 1, 2 3 of the rail network
A 3D abstraction showing the full depth of
diversity present
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Vulnerability to single (or multiple) events
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Lets remove one of the most vulnerable links
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And re-run the abstraction the impact is clear
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A framework for strategic analysis

• The recursive abstraction process provides a
  framework for flexibly analysing diversity in
  complex networks.
• A proof of concept analysis tool (A3) has been
  created by the authors to explore and validate
  this approach.
• An analysis of the main rail network of the
  Netherlands shows that it has 3 levels of
  inherent diversity.
• A vulnerability analysis shows that the loss of
  a small number of links has a significant
  impact on its diversity.
• As a result of these insights into a networks
  vulnerability, appropriate strategic action can
  be taken or prioritised.

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An Intuitive Understanding of Resiliency
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Level 0 of the main road network (aprox)
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Levels 0, 1, 2, 3 4 of the road network
A 3D abstraction showing the full depth of
diversity present
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Scenario 1 multiple operational impacts
Zwolle
Amsterdam
Rotterdam
Eindhoven
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Levels 0, 1, 2, 3 of network with Scenario 1
Scenario 1 causes a major loss in the depth of
diversity
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Vulnerability analysis with Scenario 1
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Lets remove one of the most vulnerable links
Discretionary Scenario 1
Zwolle
Urgent
Amsterdam
X
X
X
Rotterdam
X
Eindhoven
Congestion
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And re-run the abstraction the impact is clear
A severe impact on diversity if one of the V
links are lost
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Scenario 2 alternative discretionary impacts
Zwolle
Urgent
Amsterdam
X
Rotterdam
X
Eindhoven
Congestion
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Levels 0, 1, 2, 3 of network with Scenario 2
fragmented
Scenario 2 has much less impact on the depth of
diversity
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A framework for operational analysis

• A mature network, such as the main road network,
  will have a very rich inherent depth of
  diversity.
• As a consequence, such networks do not have a
  high degree of vulnerability to the loss of an
  individual link.
• However, road networks are an excellent example
  of situations where multiple events can easily
  occur.
• In these situations, the analysis tool provides
  a framework for assessing the operational
  impact of different scenarios.
• To join the Beta trials of the A3 network
  analysis tool contact the team via
  www.prolego.com