Influence Road Surface Charactertistics on Rolling Resistance

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influence of road surface characteristics on rolling resistanceAuthors: dr. G.J.van Blokland, M+P (NL), ir. W. Schwanen, M+P (NL) S.W. Boere, student TU/e (NL)

Tentative study on effects of different road surfaces on rolling resistance and the relation with rolling noise and wet gripTest programtest procedure road surface types measurement results

rolling resistance

Rolling resistance explained with surface characteristicsroad surface texture road surface mechanical impedance

Relation of rolling resistance withwet grip rolling noise

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Rolling resistance

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Test vehicleDesigned and operated by TU Gdansk

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Test vehicle: Schematic representationdirect measurement system load adjustment system

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F RRC = = tan( ) Nr

: orientation of Arm 1

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Test surfacesKloosterzande test track in the Netherlands 40 different test tracksISO 10844 SMA (0/6, 0/8, 0/11 and 0/16) Dense Asphalt Concrete 0/16 Semi-porous thin layered surfaces Porous Asphalt Concrete with various stone-sizes and layer thickness two-layer Porous Asphalt Concrete with different stone-sizes and layer thickness eight experimental rubberized surfaces two surface dressings

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Typical resultRolling resistance level as function for distance Grey area is dominated by transient effects two different tyres Uniroyal Tigerpaw (SRTT) 225/60 R16 Continental CPC2 LI98 225/60 R16

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Test results: average rolling resistanceResults for Continental tyre in categorical sequence (average over 5 measurements) Error bars indicate peak-to-peak levels2.20% 2.00% 1.80% 1.60% 1.40% 1.20% 1.00% 0.80% 0.60%1 19 20 21 22 23 2 ISO SMA 3 4 5 6 7 8 9 15 24 31 38 10 11 12 13 14 16 25 26 27 28 29 30 17 18 32 33 34 35 36 37 40 41 PAC double layer PAC rubberized surfaces surface dressings DAC Thin layered asphalt

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Rolling Resistance Coefficient [-]

Section

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Test results: average rolling resistanceResults for SRTT tyre in categorical sequence (average over 5 measurements) Error bars indicate peak-to-peak levels2.20% 2.00% 1.80% 1.60% 1.40% 1.20% 1.00% 0.80% 0.60%1 19 20 21 22 23 2 ISO SMA 3 4 5 6 7 8 9 15 24 31 38 10 11 12 13 14 16 25 26 27 28 29 30 17 18 32 33 34 35 36 37 40 41 PAC double layer PAC rubberized surfaces surface dressings DAC Thin layered asphalt

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Rolling Resistance Coefficient [-]

Section

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Test results: comparison between tyresscatter diagram of rolling resistance results of both tyres positive correlation : R2 = 0.99, slope = 1.07, residue = 0.02,2.20 2.00 1.80

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1.60

1.40 1.20 1.00 0.80 0.60 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.20

ISO SMA DAC Thin layered asphalt PAC double layer PAC rubberized surfaces surface dressings

SRTT

Continental

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Surface texture-6

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m) Texture Amplitude [dB] (Ref. = 10

60 55 50 45 40 35 30 25 20 200

S19: 20 mm SMA 0/6 S20: 25 mm SMA 0/8 S21: 30 mm SMA 0/11 S22: 40 mm SMA 0/16

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3-D laser profilometer: 2.95 x 0.3 m area 0,3 mm step and 20 m resolution

125

63

31.5

16

8

4

2

1

Wavelength [mm]

rms = effective amplitude of surface texture

SMA 0/6 SMA 0/8 SMA 0/11 SMA 0/16

rms 0.53 0.88 1.16 1.37

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Surface texture and rolling resistancesurface dressings rubberized surfaces

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Correlation between rms of surface texture and rolling resistance coefficient. Various colors indicate the surface types, slope =0.078 %/mm , R2 =0.89 , residue = 0.016

Mechanical Impedance : measurement principleharmonic excitation : F(t)=F0*sin(2f*t) resultstiffness of road surface admittance

measurement in lab

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frequency range 125 4 kHz presented result is an average over 20 excitations

rolling resistance: frequency range of interest : 250 400 Hz

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Mechanical impedancedifferences in mechanical behavior of flexible surfaces in frequency area relevant for rolling resistance

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Rolling resistance and mechanical impedanceinfluence of damping on rolling resistance ? part of the differences explained by difference in damping

1.60%

R olling res is tanc ec oeffic ient[% ]

1.40%

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1.20%

1.00%

0.80%

0.60% 32 33 34 S e c tion 35 36

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Rolling resistance and wet gripresults of ten surfaces including rubberized surfacesRolling Resistance Coefficient [%] 1.6 1.4 1.2 1.0 0.8 0.6 0 0.2 0.4 0.6 0.8 1 Wet Grip [-]

40 mm DAC 0/16 50 mm PAC 0/16 double layer PAC rubberized surfaces

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Rolling resistance and tyre/road noise

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rolling resistance and tyre/road noisesubset of dense surfacesrelation on previous sheet spoiled by effect of acoustic absorption and elasticity subset of test sections with no absorption and high mechanical impedance slope = 0.21 [%/dB] R2 = 0.79 residue = 0.14

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ConclusionsRoad Surface Characteristicsgood correlation between rms of texture profile and rolling resistance outliers are surface dressings and elastic rubberized surfaces

Rubberized surfacesthe real part of the admittance measure for energy dissipation

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in relevant frequency range (250 400 Hz) higher energy dissipation corresponds to higher rolling resistance

Effect of rolling resistance of road surfacesIn this study we found no correlation between wet grip and rolling resistance for road surfaces For dense surfaces a positive correlation between rolling noise and rolling resistance was found

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RecommendationsIt shall be generally acknowledged that road surface characteristics have a significant effect on the rolling resistance of tyres Improving sustainability of road transport shall therefore incorporate both acoustic and fuel efficiency properties of road surfaces Measurement methods, test procedures and evaluation criteria are required for large-scale implementation

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Integrated studys on the basic interaction process between tyre and road incorporating safety effects, shall be initiated on short notice