Measuring Rolling Resistance of Typical Swedish Pavements
By Dr Ulf Sandberg Swedish National Road and Transport
Research Institute (VTI)
Test car used for fuel consumption (FC) measurements on various road surfaces in 1982 by this author and colleague
Relation betw
een fuel consumption and road
surface macrotexture recorded by VTI in 1982
+ 7.5 % FC (+40 % RR)
Range of Swedish road surface textures
„Tire Technology Expo 2006” 7, 8, 9 March 2006, Stuttgart, Germany
What is rolling resistance?
22
Measurement methods and equipment
Four main methods in our work:
Rolling resistance: Measurement on drum (ISO 18164)
Fuel consumption: Measurement with instrumented car
Rolling resistance: Measurement with test tire on trailer
Rolling resistance: Coast-down with car or truck
Measurement of rolling resistance according to ISO 18164
…. intended mainly for tire testing
Facility at the Technical University of Gdansk (TUG),
Poland Technical University of Gdansk
New RR facility recently constructed at TUG designed for truck tires
2.5 m
Technical University of Gdansk
Two ref (replica) surfaces on the drum
Pilot tests in 2007, using new trailer from the Technical University of Gdansk in Poland
MIRIAM
Models for rolling resistance In Road Infrastructure Asset Management
Systems
22
Measurements in Sweden on 5 pavements for 5 tires at 50, 70 and 90 km/h
Technical University of Gdansk
Four of the five pavements
SMA 0/8
SMA 0/16 DAC 0/8
Surface dressing 8/20
Repeatability in the Swedish tests 2007
0,006
0,008
0,010
0,012
0,014
0,016
1 201 401 601 801 10011201140116011801200122012401260128013001320134013601380140014201440146014801
Time [ms]
RR
coe
ffici
ent [
-]
Tyre W6c 50km/h 1st run
Tyre W6c 50km/h 2nd run
Tyre W3c 50km/h 1st run
Tyre W3c 50km/h 2nd run
40 m
Technical University of Gdansk
Correlation betw
een rolling resistance and road surface texture
y = 0,0024x + 0,0083R2 = 0,988
0,008
0,010
0,012
0,014
0,016
0 0,5 1 1,5 2 2,5 3
MPD in mm (ISO 13473-1)
CR a
ver.
for 5
tyre
s
MIRIAM
What is MIRIAM?
22
Project started in 2009 by 11 partners from Europe, incl two from USA Pooled, internal funding (so far) Aims at providing a sustainable, environmentally friendly road infrastructure ……. by reducing rolling resistance – hence lowering CO2 emissions and increasing energy efficiency
Models for rolling resistance In Road Infrastructure Asset Management Systems
MIRIAM
22
MIRIAM
Models for rolling resistance In Road Infrastructure Asset Management
Systems
22
France Slovenia Austria
Poland
Sweden Norway
Denmark
California
Participating countries and states
Coordinating
Germany Belgium
State-of-the-Art report, June 2011 22
Rolling Resistance – Basic Information and State-of-the-Art on Measurement methods
Editor: Ulf Sandberg, Swedish National Road
and Transport Research Institute (VTI)
Trailer constructed at TUG used for measurements at VTI in Sweden
Technical University of Gdansk
Reference tires ?
Experience of this only since 3 years
Tested pavements:
11 Dense asphalt concrete, max. aggr. sizes 6, 8, 11, 16 mm
9 SMA (stone matrix asphalt), max. aggr. sizes 6, 8, 11, 16 mm
1 Hot rolled asphalt (HRA), UK type, max. aggr. size 16 mm
3 Dense-graded asphalt rubber (Arizona type adapted to Sweden), max. aggr. sizes 11, 16 mm
1 Open-graded asphalt rubber (Arizona type adapted to Sweden), max. aggr. sizes 11 mm
3 Porous asphalt concrete, single-layer, max. aggr. sizes in top layer 8, 11 mm
3 Porous asphalt concrete, double-layer, max. aggr. sizes in top layer 8, 11 mm
2 Chip seals (surface dressings), single layer, max. aggr. size 11 mm
6 Thin asphalt layers (dense), max. aggr. sizes 6, 8, 16 mm
1 Exposed aggregate cement concrete, max aggr. size 16 mm
1 SMA, max. aggr. size 16 mm, medium texture but very uneven
RRC versus texture – Data by VTI
RRC versus texture – Data by VTI
Results of all RR measurements in 2009 by TUG/VTI Average for 3 tires, normalized to 80 km/h
Effect of porous surface
Double-layer porous asphalt with 11 mm max aggr in top layer
Correlation betw
een rolling resistance and road surface texture
y = 0,0024x + 0,0083R2 = 0,988
0,008
0,010
0,012
0,014
0,016
0 0,5 1 1,5 2 2,5 3
MPD in mm (ISO 13473-1)
CR a
ver.
for 5
tyre
s
Change in RR when surface is porous asphalt
Comparison of asphalt and concrete
Correlation betw
een rolling resistance and road surface texture
y = 0,0024x + 0,0083R2 = 0,988
0,008
0,010
0,012
0,014
0,016
0 0,5 1 1,5 2 2,5 3
MPD in mm (ISO 13473-1)
CR a
ver.
for 5
tyre
s
Cement concrete EACC 0/16 vs SMA 0/16 at 80 km/h
MIRIAM
Models for rolling resistance In Road Infrastructure Asset Management
Systems
22
22Further studies needed:
1 Select and define reference tires for road surface studies
2 Effect of tire load and tire inflation
3 Effect of temperature
4 Stable calibration
5 Effect of unevenness (IRI)
6 Try also megatexture as descriptor
7 Study the effect of texture profile skew
8 Effect of ruts in the pavement
9 Effect of rain and standing water
10 Develop standard for measurement method
Some very recent results:
Round Robin (”Rodeo”) Test in MIRIAM
Measurements in Minnesota by TUG
Round Robin Test (RRT) at IFSTTAR in Nantes
BASt
BRRC
TUG = Techn Univ of Gdansk
RRC versus texture – RRT data
RRC versus texture – RRT data
Conclusions: RR vs pavement is a research area still in its infancy; esp. the measurement technology
RR is not only a tire property, but is also a pavement property, important for energy consumption in the road transport sector
Assuming MPD ranges from 0.3 to 2.5 mm, the worst pavements have about 45 % higher RR than the best ones
Corresponds to a range in fuel consumption of 5-10 %
Smooth textures are preferred; but may compromise hydroplaning
Macrotexture, measured as MPD, is a major factor influencing RR
The relation is consistently around a coefficient X of 0.0020 in the equation of RRC = X*MPD + Y (but different for SRTT and Avon AV4)
There is a substantial bias between series of measurements, the source of which is unknown
Temperature is a very influential parameter; calibrations are unstable
Acknowledgements
The author is grateful to the Technical University of Gdansk (TUG) in Poland for assisting VTI with all the RR
measurements with their “R2 trailer”
THE END
Fz
Pf
RR = Pf/Fz
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