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Infrastructure dependability, 2013 Slide 1
Critical National Infrastructure 2:
Infrastructure dependability
Ian Sommerville
Infrastructure dependability, 2013 Slide 2
Influences on dependability
• Infrastructure ownership
• Infrastructure funding...
Infrastructure dependability, 2013 Slide 3
Infrastructure ownership
• No single owner or authority
• Mixture of public and...
Infrastructure dependability, 2013 Slide 4
Infrastructure
internationalisation
• Owners may be
international
companies loc...
Infrastructure dependability, 2013 Slide 5
UK rail privatisation
British rail
Infrastructure dependability, 2013 Slide 6
Regulation
• Government
regulators are
responsible for
safety and have
powers t...
Infrastructure dependability, 2013 Slide 7
Dependability consequences
• No single organisation is responsible
for overall ...
Infrastructure dependability, 2013 Slide 8
Dependability consequences
• Companies try to avoid responsibility for
incident...
Infrastructure dependability, 2013 Slide 9
Infrastructure funding
• Infrastructure
replacement is very
expensive
• Governm...
Infrastructure dependability, 2013 Slide 10
Infrastructure replacement
• Across the developed world, ageing infrastructure...
Infrastructure dependability, 2013 Slide 11
Dependability consequences
• Because of the high costs, there is a
tendency to...
Infrastructure dependability, 2013 Slide 12
Infrastructure dependencies
• Infrastructure elements are often
dependent on e...
Infrastructure dependability, 2013 Slide 13
(Source: US DOE)
Infrastructure dependability, 2013 Slide 14
Types of dependency
• Functional
– Use of common functions by different
elemen...
Infrastructure dependability, 2013 Slide 15
Types of dependency
• Geospatial
– Components are located physically close to ...
Infrastructure dependability, 2013 Slide 16
Cascade failure
• A failure in one area cascades to
another infrastructure sec...
Infrastructure dependability, 2013 Slide 17
Cascade failure
• Failure of flood defences results in an electricity
distribu...
Infrastructure dependability, 2013 Slide 18
Mutual dependencies
• Mutual dependencies cause major
problems in the event of...
Infrastructure dependability, 2013 Slide 19
www.geography.org.uk
Infrastructure dependability, 2013 Slide 20
Single points of failure
• Several services
share some facility
so that failur...
Infrastructure dependability, 2013 Slide 21
Single point of failure
• Transport, communication and
power cables use the sa...
Infrastructure dependability, 2013 Slide 22
Shared system components
• Control systems for different
infrastructure elemen...
Infrastructure dependability, 2013 Slide 23
Shared components
• Failure of a reused component can lead
to failures in appa...
Infrastructure dependability, 2013 Slide 24
Dependability consequences
• Infrastructure systems are not
independent
• Asse...
Infrastructure dependability, 2013 Slide 25
Key points
• The fragmented ownership of national
infrastructure has overall e...
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Infrastructure dependability

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  • Transcript of "Infrastructure dependability"

    1. 1. Infrastructure dependability, 2013 Slide 1 Critical National Infrastructure 2: Infrastructure dependability Ian Sommerville
    2. 2. Infrastructure dependability, 2013 Slide 2 Influences on dependability • Infrastructure ownership • Infrastructure funding • Infrastructure dependencies
    3. 3. Infrastructure dependability, 2013 Slide 3 Infrastructure ownership • No single owner or authority • Mixture of public and private ownership • Increasing privatisation
    4. 4. Infrastructure dependability, 2013 Slide 4 Infrastructure internationalisation • Owners may be international companies located in different countries from the infrastructure that they own
    5. 5. Infrastructure dependability, 2013 Slide 5 UK rail privatisation British rail
    6. 6. Infrastructure dependability, 2013 Slide 6 Regulation • Government regulators are responsible for safety and have powers to enforce safety-related changes on companies
    7. 7. Infrastructure dependability, 2013 Slide 7 Dependability consequences • No single organisation is responsible for overall system dependability and for liaison with other infrastructure providers • Cost and budgets rather than safety are the key drivers as company shareholders have to be satisfied
    8. 8. Infrastructure dependability, 2013 Slide 8 Dependability consequences • Companies try to avoid responsibility for incidents and accidents as these mean that compensation may have to be paid to other companies or individuals • There is a tendency to try to blame other companies when things go wrong
    9. 9. Infrastructure dependability, 2013 Slide 9 Infrastructure funding • Infrastructure replacement is very expensive • Governments and companies are often reluctant to pay for infrastructure ©Stefan Kuhn (flickr) © UK Highways Agency (via Jimmy Guano)
    10. 10. Infrastructure dependability, 2013 Slide 10 Infrastructure replacement • Across the developed world, ageing infrastructure built in the 1950s and 1960s is in need of replacement. © Dennis Bratland
    11. 11. Infrastructure dependability, 2013 Slide 11 Dependability consequences • Because of the high costs, there is a tendency to delay infrastructure investment and maintenance but to wait until failures occur and then repair the infrastructure • This leads to longer periods of unavailability and disruption for users of the infrastructure
    12. 12. Infrastructure dependability, 2013 Slide 12 Infrastructure dependencies • Infrastructure elements are often dependent on each other so that failure of one element may be caused by failure of some other element elsewhere
    13. 13. Infrastructure dependability, 2013 Slide 13 (Source: US DOE)
    14. 14. Infrastructure dependability, 2013 Slide 14 Types of dependency • Functional – Use of common functions by different elements of the infrastructure • Informational – Decision making may depend on data from the same source • Shared Control – Control is from the same system/location
    15. 15. Infrastructure dependability, 2013 Slide 15 Types of dependency • Geospatial – Components are located physically close to each other • Purpose – Elements of the infrastructure may have a shared function or purpose so components may be reused • Policy – Different elements of the infrastructure may be governed by the same policies
    16. 16. Infrastructure dependability, 2013 Slide 16 Cascade failure • A failure in one area cascades to another infrastructure sector, causing failures and disruption, sometimes in quite unrelated areas
    17. 17. Infrastructure dependability, 2013 Slide 17 Cascade failure • Failure of flood defences results in an electricity distribution centre being threatened by flooding • Shut down for safety reasons • Leads to a loss of power in the local area • An ISP in that area goes offline, leading to a loss of internet service to customers who may be anywhere in the country.
    18. 18. Infrastructure dependability, 2013 Slide 18 Mutual dependencies • Mutual dependencies cause major problems in the event of failure – Communications systems depend on power – Power recovery depends on communications – Power failure that leads to loss of communications is difficult to recover from
    19. 19. Infrastructure dependability, 2013 Slide 19 www.geography.org.uk
    20. 20. Infrastructure dependability, 2013 Slide 20 Single points of failure • Several services share some facility so that failure at that facility leads to a loss of all of these services. • Power and communication cables in the same duct © Martin Pettitt (2006)
    21. 21. Infrastructure dependability, 2013 Slide 21 Single point of failure • Transport, communication and power cables use the same bridge to cross a river or sea channel
    22. 22. Infrastructure dependability, 2013 Slide 22 Shared system components • Control systems for different infrastructure elements may be supplied by the same company • Software components may be reused across systems for different types of infrastructure control
    23. 23. Infrastructure dependability, 2013 Slide 23 Shared components • Failure of a reused component can lead to failures in apparently unrelated parts of the infrastructure
    24. 24. Infrastructure dependability, 2013 Slide 24 Dependability consequences • Infrastructure systems are not independent • Assessment of the dependability of one part of the infrastructure has to consider the dependability of other infrastructure elements • Dependencies may be unknown • Contingencies for the failure of these other elements may have to be made
    25. 25. Infrastructure dependability, 2013 Slide 25 Key points • The fragmented ownership of national infrastructure has overall effects on its dependability • Infrastructure elements are rarely independent but depend on other elements of the national infrastructure • When considering the dependability of part of the infrastructure, you have to take into account its possible dependencies with other parts of the infrastructure and their dependability
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