Validation of the step theory

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TIL/T&P Masterclass by MSc student Liselotte Kroon about her graduation project on step theory and on litereature review.

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Validation of the step theory

  1. 1. Validation of the Step TheoryWitteveen+Bos E.C.M. KroonRijkswaterstaat Master Thesis TILTU Delft13/9/12 1
  2. 2. Indexn  Introduction to the Step Theoryn  Literature Studyn  Methodsn  Driving simulator Studyn  The challange of a literature study13/9/12 2
  3. 3. INTRODUCTION TO THE STEP THEORY13/9/12 3
  4. 4. Step Theoryn  Design speed of successive road elements should Q1 decrease gradually Q2 120 km/h - 100km/h - 80km/h - 50 km/hn  Goal: facilitate a safe transition in operational speed, by road design only Figuur 1, Haarlemmermeeraansluiting13/9/12 4
  5. 5. Step Theory in practicen  Speed Q1 is multiple steps lower ¨  Krappe bocht door beperkt ruimtebeslag is geaccepteerd. Extra aandacht voor compenserende maatregelenn  Speed between Q1 en Q2 differs multiple stepsn  Speed of Q2 does not connect with the underling road networkn  Q1 en Q2 are separated by a short road section, by which operational speeds at Q2 become too highn  It is unclear whether the deceleration lane can be seen as a full step13/9/12 5
  6. 6. Main goaln  Validation of the Step Theory To which extend does the step theory contribute to traffic safety at ramps and F-F connectors on Dutch motorways?13/9/12 6
  7. 7. Subquestionsn  What is the underlying basis of the step theory and is there literary support for it?n  Is there a difference in speed profiles for the degree in which the step theory is applied?n  Is there a difference in traffic safety for the degree in which the step theory is applied?n  Is there a difference found between road types in relation to the degree in which the step theory is applied, measured in speed and crash rate?n  Is there a difference found between road configurations in relation to the degree in which the step theory is applied, measured in speed and crash rate?13/9/12 7
  8. 8. Research setup13/9/12 8
  9. 9. LITERATURE STUDY13/9/12 9
  10. 10. Subquestionsn  What is the underlying basis of the step theory and is there literary support for it?n  Which independent factors are of influence on operational speeds and traffic safety in motorway curves as well?n  Which road configurations are of interest for this study?13/9/12 10
  11. 11. Conclusies [1]n  Hardly any studies towards deceleration behaviour at motorwaysn  Consistency theories on step size exist, though there is no hard validationn  Consistency indicators, like: ¨  Variability in speed Crash rate ¨  Workload, hart rate variability Road position13/9/12 11
  12. 12. Conclusies [2]n  Factors to take into account when analysing curves, like: ¨  Curve length ¨  Curve-tangent-curve ¨  Road signsn  Deceleration behaviour on deceleration lanes is likely to be dependent on the first curve radiusn  No literature on differences between connector roads and rampsn  Configurations ¨  No curve-tangent-curve13/9/12 12
  13. 13. METHODE13/9/12 13
  14. 14. General setup13/9/12 14
  15. 15. Variablesn  Stepsizen  Configurationn  Road type13/9/12 15
  16. 16. Indicators crashstudyn  Crashes13/9/12 16
  17. 17. Indicators Driving simulator [1]13/9/12 17
  18. 18. Indicators Driving simulator [2]n  Smoothness13/9/12 18
  19. 19. Indicators Driving simulator [3]n  Calculating smoothness ¨  Standerdize over time – absolute difference over time step – summation to obtain one value13/9/12 19
  20. 20. DRIVING SIMULATOR STUDY13/9/12 20
  21. 21. Limitations driving simulatorn  No hights ¨ No interchangen  No superelevationn  Difference between ramp and connector road difficult to simulate13/9/12 21
  22. 22. Setup13/9/12 22
  23. 23. Map13/9/12 23
  24. 24. Population n  45 participants n  3 became motion sick n  71% man vs. 29% n  4 other dropouts woman Age  distribution Distribution  of  driving  experience 16 14 15 14 12 Number  of  participants  [#]Number  of  participants  [#] 13 12 10 11 10 9 8 8 7 6 6 5 4 4 3 2 2 1 0 0 <25 26-­‐30 31-­‐35 36-­‐40 41-­‐45 46-­‐50 51-­‐55 56-­‐60 61-­‐65 0-­‐5 6-­‐10 11-­‐15 16-­‐20 21-­‐25 26-­‐30 31-­‐35 36-­‐40 41-­‐45 Age  of  participants  [years] Possession  of  driving  license  [years] 13/9/12 24
  25. 25. Results [1] n  Speed n  Lateral position13/9/12 25
  26. 26. Results [2]n  Steering angle n  Lateral speed13/9/12 26
  27. 27. Results [3]13/9/12 27
  28. 28. THE CHALLENGE OF A LITERATURE STUDY13/9/12 28
  29. 29. Where to start?n  Quickly gain a broad perspective on your topicn  Set clear goalsn  Structure your literature study and think of how to present your outputn  Reassess halfway!13/9/12 29
  30. 30. For what purpose?Determiningn  Variablesn  Indicatorsn  Scopen  Methodsn  Oppertunities13/9/12 30
  31. 31. Assess literaturen  Method used in papern  Populationn  Experimental conditionsn  Significancen  Be critical!13/9/12 31
  32. 32. Perform your literature review properly and you will be one step ahead of your committee13/9/12 32
  33. 33. QUESTIONS13/9/12 33

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