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