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Timothy D. Miller Fugro Consultants, Inc. Austin, TX 1

Timothy D. Miller Fugro Consultants, Inc. Austin, TX · 2012. 12. 10. · Key Processing Method • Use laser profiling techniques and theories to analyze surface texture. • Treat

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  • Timothy D. Miller

    Fugro Consultants, Inc.

    Austin, TX

    1

  • Presentation Overview

    • Pavement Surface Texture

    • Specifications

    • Measurement Methods

    • Surface Texture & Friction

    • Next Steps

    2

  • Why Surface Texture?

    • Surface texture affects the user!

    • Safety

    • Vehicle fuel economy

    • Noise

    • Surface conditions influence decision-

    making processes and asset management

    strategies of state highway agencies.

    3

  • Big Questions

    • How is texture related to friction?

    • What are desired test specifications and methods?

    • What analysis techniques are available?

    • What data is most critical for state agencies?

    4

  • Pavement Surface Texture

    • Defined by four primary ranges.

    Source: Boere, 2009

    Result of mixture

    design, material

    characteristics,

    construction practices,

    and variability.

  • Effects of Surface Texture

    • Rolling resistance

    • Friction

    • Tire wear

    • Noise

    • Vibration

    Source: ISO 13473-2, 2002

  • Specifications

    • AASHTO, ASTM, ISO standards for

    friction and texture measurement

    methods and devices.

    • Several indices have been developed,

    though a unified standard has not

    appeared.

  • Ratings and Indices

    • Roughness and Unevenness • International Roughness Index (IRI)

    • Friction Indices • International Friction Index (IFI)

    • Friction Number (FN)

    • Texture • Mean Profile Depth (MPD)

    • Mean Texture Depth (MTD)

    • Other rating systems

    8

  • Key Processing Method

    • Use laser profiling techniques and theories to analyze surface texture.

    • Treat surface profiles as signals, analyze with Discrete Fourier Transform methods to determine frequency spectral content.

    • Investigate asperity distribution, relate spectral attributes to user impacts and pavement distresses.

  • Current Texture Metrics

    • Mean profile depth (MPD)

    • Mean texture depth (MTD)

    10

    Source: ISO 13473-2, 2002

  • Effects of Texture Spectrum

    11

    Stationary

    Measurement

    Methods

    Mobile

    Measurement

    Methods

    ISO 13473-2, 2002

  • Investigating Surface Texture

    • Micro-texture

    • Rubber pad friction

    tests

    • Macro-texture

    • Texture meter

    • Sand patch

    • Laser profilers

    • Mega-texture

    • Skid trailers

    • Mobile profilers

    • Unevenness

    • Mobile profilers

    • Full-scale ride

    testers

    12

  • Effects of Texture Spectrum: Micro-Texture

    13

  • • Rotating rubber sliders contact pavement surface to produce friction profile.

    • Available for field tests.

    • Requires water supply.

    Dynamic Friction Tester (DF Tester)

    14

  • British Pendulum Tester (BPT)

    • Rubber slider

    mounted on

    pendulum contacts

    pavement surface

    while raising pointer

    on BPN scale.

    • Available for lab and

    field tests.

    15

    JIG ASSEMBLY

    SGC

    SAMPLE

    BPT

    RUBBER

    SLIDER

    BPN

    SCALE

  • Effects of Texture Spectrum: Macro-Texture

    16

  • Circular Track Meter (CTM)

    • Laser traces circle,

    which is divided into 8

    segments for analysis.

    • When combined with

    the DF Tester, the CTM

    can be used to

    calculate IFI values.

    17

  • Sand Patch Test

    • Basic, widely used

    test to estimate

    pavement mean

    texture depth (MTD).

    • Spread circle of sand

    on pavement,

    measure circle

    diameter, calculate

    MTD.

    18

  • Stationary Linear Profiler (SLP)

    • Assembly developed

    by UW-Madison for

    FHWA’s ARC program.

    • Evaluate in-service

    pavements, HMA cores

    and SGC lab samples.

    • Obtain profiles for TSA

    evaluation.

    19

  • Effects of Texture Spectrum: Mega-Texture

    20

  • Mobile Profiling Equipment

    • Automated data

    collection vehicle

    (ARAN)

    • Laser profiler in

    front, imaging

    cameras in back

    • GPS and GPR

    integration 21

  • Skid Testing

    • States contracting network-level skid projects to inform asset management strategies.

    • Requires two people, tow vehicle, skid trailer, data processing.

    22

  • Effects of Texture Spectrum: Unevenness

    23

  • How do we link all this together?

    • Texture spectral analysis

  • Pavement “Fingerprinting”

    • A person’s fingerprint distinguishes them from billions of other people.

    • Texture spectral analysis (TSA) techniques allow for unique identification of pavement surface characteristics.

    25

  • Pavement “Fingerprinting”: TSA

    • Utilize a stationary linear profiler (SLP).

    • Analyze profile using Discrete Fourier

    Transform to produce the power spectral

    density (PSD).

    • Two types of spectra derived from the PSD:

    • Amplitude Spectrum

    • Texture Level Spectrum

    26

  • Power Spectral Density

    • Describes frequency content of

    pavement signal

    27

    y = 4E-06x-1.613 R² = 0.9537

    1.E-14

    1.E-13

    1.E-12

    1.E-11

    1.E-10

    1.E-09

    1.E-08

    1.E-07

    10.00 100.00 1000.00 10000.00

    PS

    D (

    m3)

    f (cycles/m)

    Macrotexture PSD

  • Amplitude & Texture Spectra

    28

    0.00

    0.10

    0.20

    0.30

    0.40

    0.50

    0.60

    0.70

    0.11.010.0100.01000.0

    al (

    mm

    ) l (mm)

    Amplitude Spectrum, Octave Bands

    0

    10

    20

    30

    40

    50

    60

    12

    8.0

    64

    .0

    32

    .0

    16

    .0

    8.0

    4.0

    2.0

    1.0

    0.5

    Ltx

    (d

    B)

    l (mm)

    Texture Spectrum in octave bands

  • Texture Level Distribution

    29

  • Lessons Learned

    • Need full-scale field experimentation for validation!

    • Lab work demonstrates texture-friction relationship to micro-texture and macro-texture at low end of spectrum.

    • Questions remain at high end of spectrum with mega-texture and unevenness.

    30

  • Next Steps

    • Expand data collection efforts to other

    states and regions.

    • Validate findings at existing test tracks.

    • Develop pooled-fund proposal among state

    agencies.

    31

  • Acknowledgements

    • Asphalt Research Consortium,

    Federal Highway Administration

    • Modified Asphalt Research Center,

    University of Wisconsin – Madison

    • Fugro Consultants, Inc.

    32

  • Thanks for listening!

    Questions?

    Comments?

    Other Feedback?

    33