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Validation of the Step Theory

E.C.M. Kroon Master Thesis TIL

Witteveen+Bos

Rijkswaterstaat

TU Delft

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Index

n  Introduction to the Step Theory n  Literature Study n Methods n Driving simulator Study n The challange of a literature study

INTRODUCTION TO THE STEP THEORY

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Step Theory

n  Design speed of successive road elements should decrease gradually 120 km/h - 100km/h - 80km/h - 50 km/h

n  Goal: facilitate a safe transition in operational speed, by road design only

Q1

Q2

Figuur 1, Haarlemmermeeraansluiting

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Step Theory in practice

n  Speed Q1 is multiple steps lower ¨  Krappe bocht door beperkt ruimtebeslag is geaccepteerd. Extra

aandacht voor compenserende maatregelen

n  Speed between Q1 en Q2 differs multiple steps

n  Speed of Q2 does not connect with the underling road network

n  Q1 en Q2 are separated by a short road section, by which operational speeds at Q2 become too high

n  It is unclear whether the deceleration lane can be seen as a full step

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Main goal

n 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?

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Subquestions n  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?

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Research setup

LITERATURE STUDY

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Subquestions

n  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?

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Conclusies [1]

n  Hardly any studies towards deceleration behaviour at motorways

n  Consistency theories on step size exist, though there is no hard validation

n  Consistency indicators, like: ¨  Variability in speed Crash rate ¨  Workload, hart rate variability Road position

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Conclusies [2]

n  Factors to take into account when analysing curves, like: ¨  Curve length ¨  Curve-tangent-curve ¨  Road signs

n  Deceleration behaviour on deceleration lanes is likely to be dependent on the first curve radius

n  No literature on differences between connector roads and ramps

n  Configurations ¨  No curve-tangent-curve

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METHODE

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General setup

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Variables

n Stepsize n Configuration n Road type

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Indicators crashstudy

n Crashes

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Indicators Driving simulator [1]

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Indicators Driving simulator [2]

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n Smoothness

Indicators Driving simulator [3]

n Calculating smoothness ¨ Standerdize over time – absolute difference over time

step – summation to obtain one value

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DRIVING SIMULATOR STUDY

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Limitations driving simulator

n No hights ¨ No interchange

n No superelevation

n Difference between ramp and connector road difficult to simulate

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Setup

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Map

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Population

n  45 participants n  71% man vs. 29%

woman

n  3 became motion sick n  4 other dropouts

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Age  distribution

0123456789

10111213141516

<25 26-­‐30 31-­‐35 36-­‐40 41-­‐45 46-­‐50 51-­‐55 56-­‐60 61-­‐65

Age  of  participants  [years]

Num

ber  o

f  participants  [#

]

Distribution  of  driving  experience

0

2

4

6

8

10

12

14

0-­‐5 6-­‐10 11-­‐15 16-­‐20 21-­‐25 26-­‐30 31-­‐35 36-­‐40 41-­‐45

Possession  of  driving  license  [years]

Num

ber  o

f  participants  [#

]

n  Speed n  Lateral position

Results [1]

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Results [2]

n  Steering angle n  Lateral speed

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Results [3]

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THE CHALLENGE OF A LITERATURE STUDY

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Where to start?

n Quickly gain a broad perspective on your topic

n Set clear goals n Structure your literature study and think of

how to present your output

n Reassess halfway!

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For what purpose?

Determining n Variables n  Indicators n Scope n Methods n Oppertunities

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Assess literature

n Method used in paper n Population n Experimental conditions n Significance

n Be critical!

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Perform your literature review properly and you will be one step ahead of your committee

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QUESTIONS

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