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  • Young Researchers Seminar 2011

    DTU, Denmark, June 8 - 10, 2011

    Young Researchers Seminar 2013

    Lyon, France , June 5-7 2013

    THE CONTRIBUTION OF MICRO- AND MACRO-TEXTURE TO THE SKID RESISTANCE OF PAVEMENTS

    Pedro A. Serigos

    The University of Texas at Austin

  • 2THE CONTRIBUTION OF MICRO- AND MACRO-TEXTURE TO THE SKID RESISTANCE OF PAVEMENTS

    High demand for safer roads

    # of wet-weather accidents increases as skid resistance of pavement decreases

    Pavement surface friction becomes an important component of Pavement Management Systems

    Pavement surface friction is affected by its texture. More specifically, the micro- and the macro-texture.

    component wavelength Scale

    uneveness 500mm < Short stretch of

    road

    megatexture 50mm < < 500mm Tire

    macrotexture 0.5mm < < 50mm Tire/road contact

    microtexture < 0.5mmAggregates

    texture

  • 3

    Mechanisms

    Skid Resistance requires transfer of frictional force

    Complex interplay between adhesion and hysteresis forces: Hysteresis: energy loss due to

    deformation of tire

    Adhesion: short-term bond between atoms of tires and road

    Source: Moore (1972). The Friction and Lubrication of Elastomers. Pergamon Press, Oxford.

    THE CONTRIBUTION OF MICRO- AND MACRO-TEXTURE TO THE SKID RESISTANCE OF PAVEMENTS

  • 4

    Role of Texture Components

    Texture Component

    Main Function Main Benefit

    Macro-TextureRapid drainage Avoid Hydroplaning

    Deformation of tire Hysteresis

    Micro-TexturePenetrates the thin layer of

    water tire/pavement contact

    Adhesion

    THE CONTRIBUTION OF MICRO- AND MACRO-TEXTURE TO THE SKID RESISTANCE OF PAVEMENTS

  • 5

    Low speed and high speed friction measurements

    Skid resistance is currently evaluated at a spot

    Methods to evaluate friction

    British Pendulum Tester Dynamic Friction TesterLocked-wheel skid trailer

    Source: http://www.nippou.com Source: http://www.pavementinteractive.org/

    THE CONTRIBUTION OF MICRO- AND MACRO-TEXTURE TO THE SKID RESISTANCE OF PAVEMENTS

  • 6

    Spot measurements of macro-texture

    High-speeds measurements of macro-texture

    Methods to measure texture

    Sand-Patch Circular Track Meter Road Surface Analyzer

    Source: http://www.pavementinteractive.org/

    THE CONTRIBUTION OF MICRO- AND MACRO-TEXTURE TO THE SKID RESISTANCE OF PAVEMENTS

  • 7

    Future capabilities

    As technology advances, the density of the scans will increase allowing for the characterization of micro-texture at highway speeds.

    THE CONTRIBUTION OF MICRO- AND MACRO-TEXTURE TO THE SKID RESISTANCE OF PAVEMENTS

  • 8

    Textures that affect friction include both micro- and macro-texture. Currently only macro-texture is being measured.

    Previous studies found a weak relationship between friction and macro-texture.

    Separate contribution of micro and macro-texture on skid resistance is currently not fully understood.

    Problems and Motivation

    SKID RESISTANCE = f(MACRO,MICRO)

    Vision: Network level monitoring of skid resistance as a function of both micro-and macro-texture.

    THE CONTRIBUTION OF MICRO- AND MACRO-TEXTURE TO THE SKID RESISTANCE OF PAVEMENTS

  • 9

    1) Quantifying the improvement on the prediction of skid resistance when accounting for both macro- and micro-texture of the surface.

    2) Compares different ways to characterize the micro-texture to determine which one better predicts skid resistance.

    Types of Pavement surface texture

    MACRO-TEXTURE

    FINE COARSE

    MIC

    RO

    -TE

    XTU

    RE SMOOTH

    SHARP

    Objectives of the study

    THE CONTRIBUTION OF MICRO- AND MACRO-TEXTURE TO THE SKID RESISTANCE OF PAVEMENTS

  • 10

    Spot MeasurementsSM

    OO

    TH

    MIC

    RO

    -TEX

    TUR

    E

    SHA

    RP

    MACRO-TEXTURE

    FINE COARSE

    THE CONTRIBUTION OF MICRO- AND MACRO-TEXTURE TO THE SKID RESISTANCE OF PAVEMENTS

  • 11

    Collected data

    THE CONTRIBUTION OF MICRO- AND MACRO-TEXTURE TO THE SKID RESISTANCE OF PAVEMENTS

    British Pendulum Tester (BPT)

    Low Speed Friction (approx. 10km/h)

    Wet Surface Condition

    Widely used and standardized (ASTM E303-98)

    The testing error fell within 1.00 BPN at a 95 % confidence level

  • 12

    Collected data

    Circular Track Meter (CTM)

    Laser scans a circumference of 892mm

    Sampling rate: 1 point every 0.87mm

    Widely used and standardized (ASTM E2157)

    AMES Laser Texture Scanner (LTS)

    Laser scans of 7212 points per line

    Sampling rate: 1 point every 0.015mm

    Max area of scan 100mm x 75mm

    THE CONTRIBUTION OF MICRO- AND MACRO-TEXTURE TO THE SKID RESISTANCE OF PAVEMENTS

  • 13

    LTS Scanned Line

    0 5 10 15 20 25 30 35 40 45 50

    -3

    -2

    -1

    0

    1

    2

    3

    micro

    macro

    profile

    Longitudinal coordinate (mm)

    Surf

    ace

    hei

    gh

    t (m

    m)

    THE CONTRIBUTION OF MICRO- AND MACRO-TEXTURE TO THE SKID RESISTANCE OF PAVEMENTS

  • 14

    15.5 16 16.5 17 17.5 18 18.5 19 19.5

    -0.2

    -0.15

    -0.1

    -0.05

    0

    0.05

    0.1

    0.15

    0.2

    0.25

    micro

    macro

    profile

    LTS Scanned Line

    Longitudinal coordinate (mm)

    Surf

    ace

    hei

    gh

    t (m

    m)

    THE CONTRIBUTION OF MICRO- AND MACRO-TEXTURE TO THE SKID RESISTANCE OF PAVEMENTS

  • 15

    Calculated Parameters

    Spatial Domain Amplitude

    Mean Profile Depth:

    Root Mean Square:

    Max Profile Height:

    Spacing

    2-Points Slope Variance:

    6-Points Slope Variance:

    15.5 16 16.5 17 17.5 18 18.5 19 19.5

    -0.2

    -0.15

    -0.1

    -0.05

    0

    0.05

    0.1

    0.15

    0.2

    0.25

    micro

    macro

    profile

    Source: ASTM E1845 09

    THE CONTRIBUTION OF MICRO- AND MACRO-TEXTURE TO THE SKID RESISTANCE OF PAVEMENTS

    =

    =

    =

    =

    =

    + +

    =

    =

    + + + + +

  • 16

    Contact Area and Baseline

    THE CONTRIBUTION OF MICRO- AND MACRO-TEXTURE TO THE SKID RESISTANCE OF PAVEMENTS

  • 17

    Power Spectral Density (PSD)

    101

    102

    103

    10-1

    100

    101

    102

    103

    104

    105

    106

    log(Frequency) [cycles/period]

    log(P

    SD

    )

    section 1

    section 2

    section 3

    section 4

    micro 1st decade

    0.5mm

    macro 1st decade

    50mm

    THE CONTRIBUTION OF MICRO- AND MACRO-TEXTURE TO THE SKID RESISTANCE OF PAVEMENTS

  • 18

    Calculated Parameters

    Frequency Domain

    Slope of the linearized PSD

    Y intercept of the linearized PSD

    101

    102

    103

    10-1

    100

    101

    102

    103

    104

    105

    106

    log(Frequency) [cycles/period]

    log(P

    SD

    )

    section 1

    section 2

    section 3

    section 4

    micro 1st decade

    0.5mm

    macro 1st decade

    50mm

    log = 0 + 1 log()

    log(Freq)

    log

    (PSD

    )

    The correlation coefficient of the PSD for the 28 scanned

    surfaces was > 0.98

    THE CONTRIBUTION OF MICRO- AND MACRO-TEXTURE TO THE SKID RESISTANCE OF PAVEMENTS

  • 19

    Friction vs MPD

    20

    30

    40

    50

    60

    70

    80

    90

    100

    110

    120

    0 0.2 0.4 0.6 0.8 1FR

    ICTI

    ON

    BP

    T

    MICRO-TEXTURE MPD (LTS)

    MPD - LTS

    Linear (MPD - LTS)

    20

    30

    40

    50

    60

    70

    80

    90

    100

    110

    120

    0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00

    FRIC

    TIO

    N B

    PT

    MACRO-TEXTURE MPD (CTM)

    MPD - CTM

    Linear (MPD - CTM)

    THE CONTRIBUTION OF MICRO- AND MACRO-TEXTURE TO THE SKID RESISTANCE OF PAVEMENTS

  • 20

    Comparison of Models

    THE CONTRIBUTION OF MICRO- AND MACRO-TEXTURE TO THE SKID RESISTANCE OF PAVEMENTS

    Reference Model (only macro-texture):

    Incorporating the Micro-Texture Spectral Parameters:

    Variable t-stat p-valueAdjusted

    R2

    4.84 0.000.670

    2.61 0.02

    = + + + +

    = + +

    VariableMicro-texture spectral Parameters

    t-stat p-value Adjusted R2

    2.63 0.01

    0.775 4.19 0.00

    3.16 0.00

    -0.08 0.94

  • 21

    Comparison of Models

    THE CONTRIBUTION OF MICRO- AND MACRO-TEXTURE TO THE SKID RESISTANCE OF PAVEMENTS

    Incorporating the Micro-Texture Spatial Parameters:

    = + + +

    Adjusted R2 (t-stat of )

    Micro-texture ParameterBaseline

    1 mm 5 mm 10 mm 20 mm

    Am

    pli

    tud

    e

    MPDMedian 0.739 (2.626) 0.703 (1.805) 0.669 (0.946) 0.660 (0.647)

    Mean 0.668 (1.016) 0.659 (0.562) 0.657 (0.383) 0.652 (0.229)

    RMSMedian 0.730 (2.483) 0.707 (1.931) 0.688 (1.548) 0.676 (1.163)

    Mean 0.670 (1.128) 0.662 (0.821) 0.661 (0.686) 0.657 (0.560)

    MPHMedian 0.735 (2.481) 0.687 (1.492) 0.667 (0.809) 0.661 (0.547)

    Mean 0.663 (0.822) 0.657 (0.392) 0.653 (0.242) 0.648 (0.079)

    Slo

    pe SV2pts

    Median 0.744 (2.625) 0.701 (1.804) 0.671 (1.100) 0.665 (0.821)

    Mean 0.664 (0.727) 0.660 (0.457) 0.657 (0.355) 0.653 (0.250)

    SV6ptsMedian 0.746 (2.641) 0.703 (1.827) 0.671 (1.087) 0.665 (0.814)

    Mean 0.664 (0.725) 0.659 (0.447) 0.657 (0.346) 0.653 (0.

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