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# Step 2: Executing analysis

## Step 2: Executing analysis

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1. 4 December 2008 / Analysis of black spots Step 2: Executing analysis Trace common characteristics Start analysis with manoeuvre work sheet: accident type location of accidents Which type or characteristic is dominant ? Dominant? Five or more accidents: no statistical criterion, practical indication depends on total number of accidents

2. 4 December 2008 / Analysis of black spots

3. 4 December 2008 / Analysis of black spots Step 2: Execute analysis Accidents not in a dominant group, leave out of analysis Common characteristics within dominant group(s) Accidents of different natures can have same causes Use of percentages is not advised: 75% occur in the dark ! 3 of 4 accidents occur in the dark ! Use worksheets: time table analysis overview

4. 4 December 2008 / Analysis of black spots

5. 4 December 2008 / Analysis of black spots

6. 4 December 2008 / Analysis of black spots Step 2/3: work sheet analysis overview

7. 4 December 2008 / Analysis of black spots Step 2: Execute analysis Question and answer technique: does the similarity have any significance? what conclusion can be drawn from this? Are the conclusions relevant? 50% of accidents on a wet road? Relevant? Need of reference data to interpret

8. 4 December 2008 / Analysis of black spots Step 2/3: Analysis overview

9. 4 December 2008 / Analysis of black spots Step 3: formulate hypotheses Each dominant accident type or characteristic Compare conclusions after analysis: contradictory complementary Hypothesis based on total view of the analysis of each dominant group To hold connecting thread absolutely essential: use work sheets

10. 4 December 2008 / Analysis of black spots Step 3: formulate hypothesis

11. 4 December 2008 / Analysis of black spots Step 4: test hypotheses Site visit on base of hypotheses: hypothesis is right hypothesis is wrong No statistical testing! Experience /knowledge! Researcher should image himself in accident circumstances as much as possible: means of transport day / time of day light and weather circumstances Attention for approaching the location, lay-out, behaviour, attention level of road users, .

12. 4 December 2008 / Analysis of black spots Step 4: test hypotheses List with points of particular interest Observations of behaviour is very important: approach speed brake / stop behaviour head movements driver accelerating / decelerating Test the design against the guidelines is not the most important issue Take pictures and / or video

13. 4 December 2008 / Analysis of black spots Method for road sections and areas (MADA) Method based on function, form and use Functions (intended and in reality) per type of road user pedestrians cyclists cars The elements function, form and use must be tuned to one other Method is more or less overruled by the concept of sustainable safety

14. 4 December 2008 / Analysis of black spots Analysis accident process What kind of accidents do you expect regarding the road functions: hypothecally accident characteristics Compare hypothecally accident characteristics with the dominant characteristics of recorded accidents Determine accidents causes

15. 4 December 2008 / Analysis of black spots Step 4/7: Analysis overview

16. 4 December 2008 / Analysis of black spots Step 5: supplementary research Insufficient indications accidents cause(s): stop the analysis supplementary research Possibilities police reports of the accident interview involved persons or road users conflict observations observations of behaviour (using models)

17. 4 December 2008 / Analysis of black spots Step 6: Establish accident causes Establishing or rejecting hypotheses Establish each hypothesis accident cause(s) Compare the various findings: contradictory complementary Based on total view draw conclusions Use work sheets

18. 4 December 2008 / Analysis of black spots Measure: restricting visibility

19. 4 December 2008 / Analysis of black spots Measure: drawing pin

20. 4 December 2008 / Analysis of black spots Measure: plateau

21. 4 December 2008 / Analysis of black spots Step 7: determine measures Measures: infrastructure education enforcement Tune measure to road function Measure should eliminate the (assumed) causes Establish side-effects Take into account guidelines

22. 4 December 2008 / Analysis of black spots Measure example

23. 4 December 2008 / Analysis of black spots In practice

24. 4 December 2008 / Analysis of black spots Recapitulation Systematic analysis accidents: five work sheets Search for common factors: dominant groups To draw conclusions from common characteristics for improving the design or use of the location Connecting thread: ? all accidents ..? ? dominant type or character.? ? conclusions analysis.? ? hypothesis .? ? establish causes....? ? measure..? Experience with and knowledge of accident analysis is desired

25. 4 December 2008 / Analysis of black spots Content Black spot analysis

26. 4 December 2008 / Analysis of black spots What to do tomorrow ?

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