Network safety management NSM Analysis of black spots

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Network safety management (NSM) Analysis of
black spots
Cyprus December 2008

• Herman J. Moning MSc.
• Rijkswaterstaat - Centre for Transport and
  Navigation - The Netherlands

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Overview Eur Dir PPChecklists
Planning process
European Directive
Schemes/ checklists
Method RSIA
RSafety
Impact Assessm
Guidelines checklists
Global design
RS Audit Global design
Guidelines checklists
Detailed design
RS Audit Detailed design
Checklists
Construction
RS Audit Pre-opening
Checklists
Road in operation
RS Audit After opening
Method of Inspection
RS Inspection
Network Safety Mgt
Maintenance
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Presentation (NSM) Black spots
Planning process
European Directive
Schemes/ checklists
Method RSIA
RSafety
Impact Assessm
Guidelines checklists
Global design
RS Audit Global design
Guidelines checklists
Detailed design
RS Audit Detailed design
Checklists
Construction
RS Audit Pre-opening
NSM Black spots
Checklists
Road in operation
RS Audit After opening
Method of Inspection
RS Inspection
Network Safety Mgt
Maintenance
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Content Black spot analysis

• What prescribes EU-directive (October 2008)?
• Experience from The Netherlands
• Process to analyse Black spots
• What to do tomorrow in Cyprus?

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NSM-definitions (EU-directive)

• Identification of high accident concentrations
  sections
• at least the fatal accidents in previous years
  per unit of road length in relation to traffic
  flow and in case of intersections, the number of
  such accidents per location of intersections
• Identification of sections in NSM
• takes into account their potential savings in
  accident costs. For each category of roads, road
  sections shall be analyzed and ranked according
  to safety factors, like accidents concentrations,
  traffic volume and traffic typology
• Priority list of road sections where an
  improvement of infrastructure is expected to be
  highly efficient

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Content Black spot analysis

• What prescribes EU-directive (October 2008)?
• Experience from The Netherlands
• Process to analyse Black spots
• What to do tomorrow in Cyprus?

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Definitions (Dutch)

• Black spot an intersection or a short road
  section with a high number of road accidents with
  casualties
• Dutch criterion 6 or more killed or injured
  persons in three successive years
• High risk sites an intersection, a road section
  or area with a high number of accidents with or
  without casualties
• Dutch criterion 12 accidents or more, but less
  than 6 killed or injured persons in three
  successive years
• High risk figures sections with a high risk
  figure more than the average value

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Road safety map Province Utrecht
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Manual analysis of high risk locations

• Dutch Manual Analysis Traffic Accident
  Concentrations (MATAC, 1979)
• Subsidizing experiments by the Ministry (1981)
• stimulating the use of the manual
• gathering knowledge and experience (143 locations
  were evaluated)
• results were published by CROW (1993)

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Results research / evaluations

• Evaluation (3 years before and after)
• in average 32 reduction in accidents
• reduction in accidents with injured 45
• 50 of locations the reduction in accidents is
  not significant
• Effects depend of the quality of analysis
• incorrect interpretation of results
• deviate from main process or the connecting
  thread
• Infrastructure measures are most effective
• reducing speeds
• less sensitive for violations

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Recommendations

• Analysis of high risk sites of great value to
  improve road safety
• Reconstruction / maintenance works always
  perform an analysis of accidents
• After a serious accident many opinions
• risk that measures do not solve the problem(s)
• risk that investments are higher than necessary
• Measures should be based on thorough, objective
  analysis of the problem(s) POGSE
• Prevent is better than cure sustainable safety

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Example left turning lane
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Approach of road safety
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Objectives accident analysis

• To draw conclusions from similarities in accident
  characteristics in order to improve the design or
  use of that location or section
• Investigations into main causes of accidents
• human factors 95
• road factors 18
• vehicle factors 6
• Good, uniform design simplifies the driving task
• Design of infrastructure influences behaviour
• Behaviour is not only enforced by law (more or
  less remaining free) but actually enforced by
  infrastructure

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New, revised manual (1992)

• To revise the old manual
• To tackle scattered accidents

• Manual analysis of high risk sites, sections or
  areas
• In total 5 parts
• 1 Selection of high risk sites
• 2 Reference figures
• 3 Analysis of high risk locations (MATAC)
• 4 Analysis of high risk sections or areas (MASA)
• 5 Analysis of special groups in areas (MAGA)

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Selection of locations

• List of all locations
• threshold 5 accidents in three successive years
• Clear the list
• changed road functions
• recent reconstructions
• Possible weight factors
• Killed 5
• serious injured 3
• slight injured 1
• material damage 0,5

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Essence of analysis

• Every accident is unique
• more or less coincidence of circumstances
• every accident has its own chain of preceding
  events
• mostly more than one possible cause can be
  indicated
• Circumstances or failure chances directly
  preceding the collision moment
• In practice also similarities between accidents
• Analysis focuses mainly on the failure chances in
  the situation directly preceding the moment of
  collision

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Accident scheme
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Data available

• Registration of accidents is incomplete (NL)
• killed 94
• injured, hospital 60
• injured, first aid 16
• slightly injured lt 16
• only material damage ltltlt 16
• Data every accident is limited. No insight into
  the entire preceding chain of events. Many
  details are not known and not recorded
• Data is solely based on conclusions of the duty
  police officer after the accident

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Application accident analysis

• All (recorded) accidents / collisions
• Minimum number of accidents
• with small number great chance incidental factors
  are (partly) determinant
• ? 10 accidents in 3 - 5 successive years
• ? 5 accidents in 3 - 5 years with a similar
  characteristic
• a practical lower limit reliability of results
• Locations
• all kinds of intersections
• road sections

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Content Black spot analysis

• What prescribes EU-directive (October 2008)?
• Experience from The Netherlands
• Process to analyse Black spots
• What to do tomorrow in Cyprus?

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Process
no
yes
yes
no
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Step 1 collect data (1)

• Accident data (3-5 years preceding the study)
• Traffic data
• existing or foreseen road function
• traffic volumes (short cut)
• specific group of road users
• Drawing of the location (1 500)
• reconstructions
• Additionally data
• speed data
• experience police
• complaints residents

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Step 1 Processing data (2)

• Systematically sorting of data
• keep overview
• keep main process or continuous thread
• Use work sheets
• manoeuvre worksheet
• accident scheme

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Step 1 Manoeuvre work sheet
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Step 1 Manoeuvre work sheet (example)
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Step 1 Accident scheme
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Step 1 Accident scheme
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Step 1 Accident scheme (2)