influence of road surface characteristics on rolling resistance

Authors: dr. G.J.van Blokland, M+P (NL), ir. W. Schwanen, M+P (NL)

S.W. Boere, student TU/e (NL)

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Tentative study on effects of different road surfaces on rolling resistance and the relation with rolling noise and wet grip

Test programtest procedureroad surface typesmeasurement results

Rolling resistance explained with surface characteristicsroad surface textureroad surface mechanical impedance

Relation of rolling resistance withwet griprolling noise

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Rolling resistance

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Test vehicle

Designed and operated by TU Gdansk

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Test vehicle: Schematic representation

)tan(θNFRRC r ==

direct measurement system

θ : orientation of Arm 1

load adjustment system

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Test surfaces

Kloosterzande test track in the Netherlands40 different test tracks

ISO 10844SMA (0/6, 0/8, 0/11 and 0/16)Dense Asphalt Concrete 0/16Semi-porous thin layered surfaces Porous Asphalt Concrete with various stone-sizes and layer thicknesstwo-layer Porous Asphalt Concrete with different stone-sizes and layer thicknesseight experimental rubberized surfacestwo surface dressings

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Typical resultRolling resistance level as function for distanceGrey area is dominated by transient effectstwo different tyres

Uniroyal Tigerpaw (SRTT) 225/60 R16Continental CPC2 LI98 225/60 R16

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Test results: average rolling resistance Results for Continental tyre in categorical sequence (average over 5 measurements)Error bars indicate peak-to-peak levels

0.60%

0.80%

1.00%

1.20%

1.40%

1.60%

1.80%

2.00%

2.20%

1 19 20 21 22 23 2 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

ISO SMA DACThin layeredasphalt

PAC double layer PAC rubberized surfaces surfacedressings

Section

Rol

ling

Res

ista

nce

Coe

ffici

ent [

-]

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Test results: average rolling resistance Results for SRTT tyre in categorical sequence (average over 5 measurements)Error bars indicate peak-to-peak levels

0.60%

0.80%

1.00%

1.20%

1.40%

1.60%

1.80%

2.00%

2.20%

1 19 20 21 22 23 2 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

ISO SMA DAC Thin layeredasphalt

PAC double layer PAC rubberized surfaces surfacedressings

Section

Rol

ling

Res

ista

nce

Coe

ffici

ent [

-]

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Test results: comparison between tyresscatter diagram of rolling resistance results of both tyrespositive correlation : R2 = 0.99, slope = 1.07, residue = 0.02,

0.60

0.80

1.00

1.20

1.40

1.60

1.80

2.00

2.20

0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.20

Continental

SRTT

ISOSMADACThin layered asphaltPACdouble layer PACrubberized surfacessurface dressings

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Surface texture

3-D laser profilometer:

•2.95 x 0.3 m area

•0,3 mm step and 20 μm resolution

12481631.56312520020

25

30

35

40

45

50

55

60

65

Wavelength [mm]

Text

ure

Am

plitu

de [d

B] (

Ref

. = 1

0 -6

m)

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

rms = effective amplitude of surface texture

rmsSMA 0/6 0.53SMA 0/8 0.88SMA 0/11 1.16SMA 0/16 1.37

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Surface texture and rolling resistance

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

rubberized surfaces

surface dressings

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Mechanical Impedance : measurement principle

measurement in labfrequency range 125 – 4 kHzpresented result is an average over 20 excitations

harmonic excitation :F(t)=F0*sin(2πf*t)result

stiffness of road surfaceadmittance

rolling resistance:frequency range of interest :250 – 400 Hz

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

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Rolling resistance and mechanical impedance

0.60%

0.80%

1.00%

1.20%

1.40%

1.60%

32 33 34 35 36

S ectionRolling res

istance

 coefficien

t [%

]

•influence of damping on rolling resistance ?

•part of the differences explained by difference in damping

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Rolling resistance and wet grip

results of ten surfaces including rubberized surfaces

0.6

0.8

1.0

1.2

1.4

1.6

0 0.2 0.4 0.6 0.8 1Wet Grip [-]

Rol

ling

Res

ista

nce

Coe

ffici

ent [

%]

40 mm DAC 0/1650 mm PAC 0/16double layer PACrubberized surfaces

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Rolling resistance and tyre/road noise

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rolling resistance and tyre/road noise subset of dense surfaces

relation on previous sheet spoiled by effect of acoustic absorption and elasticitysubset of test sections with no absorption and high mechanical impedance

slope = 0.21 [%/dB]

R2 = 0.79

residue = 0.14

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Conclusions

Road Surface Characteristicsgood correlation between rms of texture profile and rolling resistanceoutliers are surface dressings and elastic rubberized surfaces

Rubberized surfacesthe real part of the admittance measure for energy dissipationin 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 surfacesFor dense surfaces a positive correlation between rolling noise and rolling resistance was found

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Recommendations

It shall be generally acknowledged that road surface characteristics have a significant effect on the rolling resistance of tyresImproving sustainability of road transport shall therefore incorporate both acoustic and fuel efficiency properties of road surfacesMeasurement methods, test procedures and evaluation criteria arerequired for large-scale implementation Integrated study’s on the basic interaction process between tyre and road incorporating safety effects, shall be initiated on short notice