NIAGARA FALLS
NOVEMBER 2007
CUPGA
CANADIAN USER PRODUCER GROUP FOR ASPHALT
FRICTIONAL CHARACTERISTICS OF PAVEMENTS
‘GET A GRIP’
JOHN EMERY
www.jegel.com
PRESIDENT
JEGEL GROUP, TORONTO
ADJUNCT PROFESSOR, McMASTER UNIVERSITY
jemery@jegel.com
THREE PRINCIPAL ELEMENTS OF SAFE TIRE-PAVEMENT INTERACTION
DURING A WET WEATHER, HIGH SPEED, ABORTED TAKEOFF, FOR INSTANCE
FLIGHT CREW OPTIMIZED
THROUGH RIGOROUS TRAINING
AND SIMULATION
GEAR/THRUST REVERSER/BRAKE/TIRE SYSTEMS
OPTIMIZED BY AIRCRAFT DESIGNERS AND TIRE
MANUFACTURERS
RUNWAY
SURFACE FRICTION
THE TECHNICAL ASSISTANCE OF ALAIN DUCLOS AND JESSICA HERNANDEZ OF JEGEL IS GRATEFULLY ACKNOWLEDGED
CUPGA
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NOVEMBER 2007
PERFORMANCE-RELATED SURFACE CONDITION PARAMETERS
WORLD ROAD ASSOCIATION (PIARC) TECHNICAL COMMITTEE 4.2
ROAD VEHICLE INTERACTION
• SYNTHESIS OF PERFORMANCE-RELATED SURFACE CONDITION MEASUREMENTS FOR
PARAMETERS (PROPERTIES) TYPICALLY USED FOR ACCEPTANCE OF ROAD WORK
 SHORT TERM (AS CONSTRUCTED OR REHABILITATED)
 LONGER TERM (WARRANTY, PERFORMANCE-RELATED CONTRACTS AND MAINTENANCE
CONTRACTS, FOR INSTANCE)
• ENROUTE PERFORMANCE-BASED SURFACE CONDITION MEASUREMENTS
• INCLUDING MEASUREMENT METHOD, METHODOLOGY, QUALITY AND REPORTING
• CURRENT, TRENDS/FUTURE, ‘LOW TECH’ AND ‘HIGH TECH’
• INTERPRETATION AND USER GUIDELINES FOR THE ACCEPTANCE PARAMETERS
• RECOMMENDATIONS ON ACCEPTANCE CRITERIA (NOT SPECIFICATIONS)
• PARAMETERS REVIEWED AND ACCEPTED FOR INTERPRETATION, USER GUIDELINES AND
ACCEPTANCE CRITERIA
 SMOOTHNESS (INTERNATIONAL ROUGHNESS INDEX, IRI)
 IRREGULARITIES (‘BUMPS’)
 SURFACE CONDITION (‘DISTRESSES’ – CRACKING, TEXTURE, SEGREGATION, RAVELLING/RUTTING,
FLUSHING, OTHER?, TYPICALLY AS A PAVEMENT CONDITION INDEX)
 PERMEABILITY
 FRICTION
 NOISE (PARTICULARLY URBAN)
 DEFLECTION (STRUCTURAL CONDITION)
 OTHERS? (REFLECTANCE, FOR INSTANCE)
• ABILITY TO INCORPORATE NEW SURFACE CONDITION FEATURES SUCH AS TOP-DOWN
CRACKING
CUPGA
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NOVEMBER 2007
FRICTIONAL CHARACTERISTICS OF PAVEMENT SURFACES
ROADS, HIGHWAYS AND AIRPORTS
THERE IS MUCH RESEARCH IN PROGRESS
• FOR INSTANCE, WORK WITH INTELLIGENT TRANSPORTATION SYSTEMS
…
CUPGA
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NOVEMBER 2007
INTERACTION OF TIRES WITH PAVEMENT SURFACES
JEGEL
•
•
•
•
•
TIRE DESIGN IS OPTIMIZED FOR ANTICIPATED SERVICE CONDITIONS
MUCH TIRE DEVELOPMENT CARRIED OUT FOR HIGH PERFORMANCE
CAR RACING AND AIRCRAFT LANDING CONDITIONS
INTEGRITY OF TIRE STRUCTURES AND FRICTION VALUES OPTIMIZED
ALL THE CONTROL FUNCTIONS OF A ROAD VEHICLE ARE
TRANSMITTED THROUGH THE TIRES (SOME AERODYNAMIC
EFFECTS AT HIGH SPEEDS)
RACE CAR DRIVERS AND PILOTS, ARE WELL PAID FOR ‘DRIVING’ SKILLS
MOLSON INDY LAKE SHORE BOULEVARD
STONE MASTIC ASPHALT
CUPGA
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NOVEMBER 2007
INTERACTION OF TIRES CONTINUED
•
TIRES ARE A KEY COMPONENT OF VEHICLES AND AIRCRAFT
‘WHERE THE RUBBER MEETS THE PAVEMENT’
•
TIRE MATERIAL AND TREAD PATTERN OPTIMIZED TO
INTERACT WITH PAVEMENT SURFACE MICROTEXTURE FOR
HIGH FRICTIONAL RESISTANCE AT ALL SPEEDS
•
TIRE PATTERN OPTIMIZED TO INTERACT WITH PAVMENT
SURFACE MACROTEXTURE TO PROVIDE BULK WATER
DRAINAGE ESSENTIAL AT HIGH SPEEDS
BOEING 777
NOTE TIRE - PAVEMENT LANDING FRICTION
CUPGA
GET A GRIP
NOVEMBER 2007
FACTORS INFLUENCING
SIZE
HIGHWAY SAFETY
MASS DISTRIBUTION
SPEED
GALLAWAY AND EPPS, ASCE, 1972
DYNAMICS
CORNERING
OTHER
S
VEHICLE
RUBBER COMPOSITION
THREAD PATTERN
TIRE
HIGHWAY
SAFETY
LOAD
CONTACT AREA
PRESSURE
CORD ANGLE
SURFACE CONSTRUCTION
SURFACE MAINTENANCE
AGGREGATE TYPE
BINDING AGENT
PLIES
ROADWA
Y
PAVEMENT
MACROTEXTURE
SURFACE TEXTURE
MICROTEXTURE
ROAD ROUGHNESS
SURFACE CONTAMINATION
GEOMETRICS
HAPPY
TEMPERATURE
INTERSTECTION
SUPER-ELEVATION
DEPRESSED
DRIVER
DRINKING
DRUGS
SIGHT
REFLEX
CROWN
GRADE
CURVATURE
CROSS SLOPE
CUPGA
GET A GRIP
NOVEMBER 2007
ONTARIO ROAD SURFACE CONDITION BY CLASS OF COLLISION, 1996
ROAD
C L A S S O F C O L L IS IO N
SURFACE
C O N D IT IO N
FATAL
P E R S O N A L IN J U R Y
PROPERTY DAMAGE
TOTAL
PERCENT
NUMBER
PERCENT
NUMBER
PERCENT
NUMBER
PERCENT
DRY
522
6 4 .0
3 5 ,7 0 8
6 1 .8
8 8 ,0 2 8
5 6 .3
1 2 4 ,2 5 8
5 7 .8
W ET
154
1 8 .9
1 4 ,2 9 3
2 4 .7
3 6 ,7 5 5
2 3 .5
5 1 ,2 0 2
2 3 .8
LOOSE SNOW
23
2 .8
1 ,6 5 9
2 .9
7 ,2 5 8
4 .6
8 ,9 4 0
4 .2
SLUSH
24
2 .9
1 ,2 0 1
2 .1
4 ,1 7 9
2 .7
5 ,4 0 4
2 .5
PACKED SNOW
21
2 .6
1 ,2 1 4
2 .1
6 ,0 8 9
3 .9
7 ,3 2 4
3 .4
IC E
57
7 .0
3 ,2 4 9
5 .6
1 2 ,8 1 9
8 .2
1 6 ,1 2 5
7 .5
MUD
-
-
15
-
69
-
84
-
L O O S E S A N D /G R A V E L
7
0 .9
283
0 .5
652
0 .4
942
0 .4
S P IL L E D L IQ U ID
1
0 .1
12
-
31
-
44
-
OTHER
7
0 .9
157
0 .3
537
0 .3
701
0 .3
TOTAL
816
1 0 0 .0
5 7 ,7 9 1
1 0 0 .0
1 5 6 ,4 1 7
1 0 0 .0
2 1 5 ,0 2 4
1 0 0 .0
A D A P T E D F R O M 1 9 9 6 O N T A R IO R O A D S A F E T Y A N N U A L R E P O R T
M T O ,1 9 9 6
B R IE F N O T E O N 1 9 7 3 A N D 1 9 7 4 D A IL Y W E A T H E R D A T A F O R T H E H A M IL T O N A R E A
O V E R T H E 'N O -IC E P E R IO D ' A N D 'D A Y L IG H T ' ( M A Y 1 T O O C T O B E R 3 1 D A Y L IG H T
D A T A P E R IO D A D O P T E D )
- S IX P E R C E N T O F T H E D A Y L IG H T H O U R S E X P E R IE N C E D R A IN
- A D A Y L IG H T W E T R O A D C O N D IT IO N O F A P P R O X IM A T E L Y
T E N P E R C E N T IF A R E A S O N A B L E D R Y IN G P E R IO D IS A S S U M E D
K R A K O W S K I, E M E R Y A N D P A L O M B E L L A , C T A A , 1 9 7 6
"S K ID R E S IS T A N C E O F T H E U R B A N C O N T E X T "
CUPGA
GET A GRIP
NOVEMBER 2007
REDUCTION OF POTENTIAL SKIDDING SITUATIONS
THREE POSSIBLE ALTERNATIVES
RELATED TO
DRIVER, VEHICLE/TIRES AND ROAD SURFACES
1. IMPROVED DRIVER AWARENESS OF SLIPPERY SITUATIONS TO
ALLOW APPROPRIATE ADJUSTMENTS IN DRIVING HABIT SUCH AS
REDUCING SPEED TO THAT COMPATIBLE WITH THE AVAILABLE
SKID RESISTANCE
2. IMPROVED VEHICLE/TIRE DESIGN TO RESIST SKIDDING THROUGH
ANTI-LOCKING DEVICES AND MODIFICATIONS TO TIRE
CONSTRUCTION, TREAD PATTERN, COMPOUND, ETC.
3. IMPROVED ROAD SURFACES THROUGH CHANGING AGGREGATES
AND/OR MIX DESIGNS TO ENHANCE FRICTIONAL
CHARACTERISTICS OF THE SURFACE
KRAKOWSKI, EMERY AND PALOMBELLA, CTAA, 1976
CUPGA
GET A GRIP
NOVEMBER 2007
SCHEMATIC DIAGRAM OF PARTIALLY HYDROPLANING TIRE ON
FLOODED RUNWAY PAVEMENT
TIRE
VELOCITY
WATER
PAVEMENT
SURFACE
3
2
1
ZONE 1 – BULK WATER (FLUID) DRAINAGE THROUGH MACROTEXTURE
ZONE 2 – THIN WATER (FLUID) FILM DRAINAGE THROUGH MICROTEXTURE
ZONE 3 – DRY CONTACT REGION
USAF, SWIFT, 2000
BULK FLUID DRAINAGE IS IMPORTANT TO MAINTAINING
TIRE – PAVEMENT ADHESION (FRICTION) AT HIGH SPEEDS
CUPGA
GET A GRIP
NOVEMBER 2007
MICROTEXTURE
COURTESY OF HUMBLE
EQUIPMENT COMPANY INC.
SKIDABRADER TM
MAGNIFICATION OF
ORIGINAL PHOTOGRAPH 40X
MICROTEXTURE DESCRIBES THE MICROSCOPIC ANGLES AND POINTS ON BEDDING MORTAR
GRANULES AND ON THE FACE AREAS OF EXPOSED AGGREGATE. THIS TEXTURE RUPTURES
THE THIN FILM OF WATER THAT CLINGS TO THE SURFACE AFTER THE MACROTEXTURE HAS
EVACUATED THE RUNNING WATER. THESE WELL DEFINED EDGES PROVIDE A TOOTH
PATTERN THAT WILL ALSO ENHANCE SURFACE FRICTION IN DRY WEATHER.
(HUMBLE)
CUPGA
GET A GRIP
NOVEMBER 2007
MACROTEXTURE
COURTESY OF HUMBLE
EQUIPMENT COMPANY INC.
SKIDABRADER TM
NO MAGNIFICATION OF
ORIGINAL PHOTOGRAPH
MACROTEXTURE IS THE GEOMETRIC RUGOSITY THAT IS QUITE OBVIOUS AND VISIBLE. IT PROVIDES
SURFACE CANALS THAT ALLOW WATER TO ESCAPE FROM BETWEEN THE TIRE AND ROAD DURING
WET WEATHER. THE MORE MACROTEXTURE DEPTH AVAILABLE, THE GREATER THE RESISTANCE TO
HIGH SPEED HYDROPLANING. THE SAND PATCH TEST, DESCRIBED IN ASTM DESIGNATION E965-83,
CAN MEASURE MACROTEXTURE DEPTH. TIRE-PAVEMENT FRICTIONAL CHARACTERISTICS
CORRELATE GENERALLY WITH THESE TESTS.
(HUMBLE)
CUPGA
GET A GRIP
NOVEMBER 2007
TEXTURE
POSITIVE TEXTURE
MICROTEXTURE
(TEXTURE OF THE STONE)
MACROTEXTURE
(OVERALL TEXTURE OF ROAD)
NEGATIVE TEXTURE
VOIDS
ASPHALT
BINDER
ADAPTED FROM AA, 2005
CUPGA
GET A GRIP
NOVEMBER 2007
GENERALIZED ILLUSTRATION OF SCALE OF TEXTURE
SURFACE
MACRO
(LARGE)
MICRO
(FINE)
CREECH 1981
CUPGA
GET A GRIP
NOVEMBER 2007
INTERACTION OF PAVEMENT SURFACE IRREGULARITIES AND
TIRE/SUSPENSION SYSTEMS
T IR E /P AV E M E N T
C O N T AC T AR E A
W AV E L E N G T H (m m )
R AN G E O F
0 .0 0 1
0 .0 1
0 .1
1
M IC R O T E X T U R E
10
100
M AC R O T E X T U R E
1 m
M EG ATEXTU R E
10 m
100 m
UNEVENNESS
IR R E G U L AR IT IE S
R O L L IN G R E S IS T AN C E
S U S P E N S IO N L O S S E S
AD H E S IO N
D R AIN AG E
R ID IN G C O M F O R T
S K ID R E S IS T AN C E
R O AD H O L D
O P T IC AL P R O P E R T IE S
R O AD W E AR
P E R F O R M AN C E
S P L AS H & S P R AY
T IR E W E AR
V E H IC L E W E AR
T IR E /R O AD N O IS E
EXTERNAL
R E D U C T IO N
IN T E R N A L A N D
EXTERNAL
P R O D U C T IO N
PIARC C1, 1995
N E C E S S AR Y
AV O ID
NOTE: WHILE DEVELOPED FOR ROAD SURFACES, GENERALLY APPLICABLE FOR RUNWAY SURFACES
CUPGA
GET A GRIP
NOVEMBER 2007
SOME ARE HAPPY WITH WATER, SNOW AND ICE
BUT NOT THE TIRE - PAVEMENT INTERFACE
WINTER PAVEMENT CONDITIONS ARE VERY IMPORTANT
CUPGA
GET A GRIP
NOVEMBER 2007
MEASUREMENTS OF MICROTEXTURE AND MACROTEXTURE
JEGEL
MICROTEXTURE – PORTABLE PENDULUM METHOD
NOTE: THE SURFACE IS GENERALLY
TESTED IN THE WET CONDITION
MACROTEXTURE
SAND PATCH METHOD
OUTFLOW METER METHOD
CUPGA
GET A GRIP
NOVEMBER 2007
MEASUREMENT OF AIRPORT FRICTIONAL CHARACTERISTICS
FRICTION MONITORING WITH GRIP TESTER – JEGEL USES THE GRIP TESTER FOR BOTH HIGHWAY
AND AIRPORT FRICTION MONITORING
CUPGA
GET A GRIP
NOVEMBER 2007
WHILE THE AIRPORT FOCUS IS GENERALLY ON THE FRICTIONAL
CHARACTERISTICS OF RUNWAY PAVEMENT SURFACES, IT IS IMPORTANT TO
PROVIDE APPROPRIATE FRICTIONAL CHARACTERISTICS FOR ALL AIRSIDE
PAVEMENT SURFACES
CUPGA
GET A GRIP
NOVEMBER 2007
TYPICAL AIRPORT CORRELATION AND FRICTION
RATING FOR EQUIPMENT READINGS
NOMINAL TEST SPEED 65 KM/H
E q u ip m e n t
E q u ip m e n t R e a d in g
G rip
T e s te r
J am e s
B ra k e
In d e x
MU
M e te r
A d e q u a te
> 0 .4 9
> 0 .5 8
> 0 .5 0
> 0 .5 4
> 0 .5 1
> 0 .5 9
> 0 .5 3
> 0 .5 1
5
M a rg in a l
0 .3 4 –
0 .4 9
0 .4 0 –
0 .5 8
0 .3 5 –
0 .5 0
0 .3 8 –
0 .5 4
0 .3 5 –
0 .5 1
0 .4 2 –
0 .5 9
0 .3 7 –
0 .5 3
0 .3 7 –
0 .5 1
3 -4
U n s a tis fa c to ry < 0 .3 3
< 0 .3 9
< 0 .3 4
< 0 .3 7
< 0 .3 4
< 0 .4 1
< 0 .3 6
< 0 .3 6
1 -2
F ric tio n
R a tin g
S u rfa c e R u n w a y B V -1 1
Locked
D ecel
F ric tio n F ric tio n S k id d o W he e l
M e te rs
T e s te r T e s te r
M e te r
D e v ic e s
In te rn a tio n a l
C iv il A via tio n
O rg a n iza tio n
IC A O In d e x
ADAPTED FROM GREENE, AFCESA, SWIFT 2001
CUPGA
GET A GRIP
NOVEMBER 2007
RUNWAY FRICTION MONITORING WITH GRIPTESTER
100
90
S AAB S T AN D AR D F R IC T IO N T E S T E R C O N D IT IO N S :
R U N W AY AV E R AG E F R IC T IO N N U M B E R = 6 0
6 5 k m /h , 0 .5 m m W AT E R 3 m L E F T AN D R IG H T O F C E N T R E L IN E
70
S A A B F R IC T IO N N U M B E R
S T A N D A R D F R IC T IO N T E S T E R
80
T R A N S P O R T C A N A D A M A IN T E N A N C E P L A N N IN G
60
R U N W A Y A V E R A G E F R IC T IO N L E V E L = 6 0
T R A N S P O R T C A N A D A M IN IM U M A C T IO N
50
R U N W A Y A V E R A G E F R IC T IO N L E V E L = 5 0
T R A N S P O R T C A N A D A M A IN T E N A N C E
40
P L A N N IN G
1 0 0 m S E C T IO N L E V E L = 4 0
T R A N S P O R T C A N A D A M IN IM U M A C T IO N
30
1 0 0 m S E C T IO N L E V E L = 3 0
20
10
0
5+ 200
5+ 700
6+ 200
C H A IN A G E ( M E T R E S )
6+ 700
7+ 200
CUPGA
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NOVEMBER 2007
ENHANCED TIRE/PAVEMENT INTERACTION
•
•
•
OF THE THREE PRINCIPAL ELEMENTS OF SAFE TIRE/PAVEMENT
INTERACTION – DRIVER/FLIGHT CREW, GEAR/THRUST
REVERSER/BRAKE/TIRE SYSTEMS AND RUNWAY SURFACE FRICTION
-THE PAVEMENT ENGINEER PLAYS A KEY ROLE WITH THE TIREPAVEMENT SURFACE INTERFACE PROVISION AND MAINTENANCE
OF APPROPRIATE LEVELS OF MICROTEXTURE, MACROTEXTURE,
SURFACE WATER DRAINAGE, AND SNOW AND ICE CONTROL
WHILE THE IMPORTANCE OF SNOW AND ICE CONTROL IS CLEARLY
RECOGNIZED, IT WILL NOT BE COVERED HERE. PLEASE REVIEW
ACTIVITIES OF CAPTG FOR INSTANCE
PROVIDE HIGH FRICTIONAL CHARACTERISTIC SURFACES
CONSTRUCT NEW SURFACE WITH THE DESIRED PROPERTIES
SELECTION OF MATERIALS
MIX TYPES AND DESIGNS
CONSTRUCTION METHODS
REMEDIATION OF OLD SURFACE WITH POOR FRICTIONAL
CHARACTERISTICS
TREAT SURFACE
OVERLAY SURFACE
CUPGA
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NOVEMBER 2007
HMA TYPES WITH ENHANCED
FRICTIONAL PROPERTIES
JEGEL
SUPERPAVE SURFACE COURSE
STONE MASTIC ASPHALT
OPEN GRADED FRICTION COURSE
CUPGA
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NOVEMBER 2007
FUNCTIONAL PROPERTIES OF WEARING COURSES
COMPARED TO DENSE GRADED ASPHALT CONCRETE
A S P A H L T P A V E M E N T W E A R IN G C O U R S E T Y P E
PROPERTY
STONE
M A S T IC
ASPHALT
M A S T IC
ASPHALT
PLUS
P R E -C O A T E D
C H IP P IN G S
VERY
SOFT
ASPHALT
CONCRETE
O IL G R A V E L
V E R Y S O FT A S P H A LT
O IL G R A V E L G R A D IN G
C O L D E M U L S IO N M IX
O IL G R A V E L G R A D IN G
POROUS
ASPHALT
CONCRETE
SURFACE
TREATMENT
'H IG H '
PERFORMANCE
C O L D E M U L S IO N M IX
F R IC T IO N
+
=
=
=
(+ )
+
W E A R R E S IS T A N C E
+
+
=
-
-
=
D E F O R M A T IO N R E S IS T A N C E
+
=
-
-
=
-
S T IF F N E S S
=
=
-
-
=
-
F L E X IB IL IT Y
=
=
+
+
(-)
=
=
+
+
=
+
+
=
=
=
=
F A T IG U E
=
W A T E R R E S IS T A N C E
+
a
(+ ) +
a
D E N S IT Y
=
+
(-)
-
-
+
P E R M E A B IL IT Y
=
=
=
(+ )
+
=
(-)
=
=
+
-
-
+
+
=
=
=
=
=
(+ )
+
N O IS E A T T E N U A T IO N
(+ ) +
LOW TEMPERATURE
=
+
a
a
=
L IG H T R E F L E C T IO N
+
a.
BETTER
=
EQUAL
-
W ORSE
( )
U N C E R T A IN E V A L U A T IO N
O N T A R IO 'E X P E R IE N C E ' (J E G E L ) W IT H W A T E R S P R A Y A L S O
NOTE: WHILE DEVELOPED FOR ROAD SURFACES, GENERALLY
APPLICABLE FOR RUNWAYS
+
A D A P T E D F R O M R O A D 9 4 , S W E D IS H N R A , 1 9 9 7
CUPGA
GET A GRIP
NOVEMBER 2007
ENHANCED MACROTEXTURE AND SURFACE DRAINAGE
JEGEL
GROOVED ASPHALT CONCRETE
SAPPORO, JAPAN
DIAMOND GROUND CONCRETE
GROOVED CONCRETE
PEARSON RUNWAY 06/24 BEFORE HMA OVERLAY
TYPICAL RUNWAY PAVEMENTS
CUPGA
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NOVEMBER 2007
RESTORING RUNWAY ASPHALT PAVEMENT
MICROTEXTURE AND MACROTEXTURE
JEGEL
SKIDABRADER RESTORING MICROTEXTURE AND MACROTEXTURE TO RUNWAY ASPHALT CONCRETE
PAVEMENT, CFB TRENTON
CUPGA
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NOVEMBER 2007
RESTORING RUNWAY ASPHALT PAVEMENT
SKID ABRADER
JEGEL
CLOSEUP OF ASPHALT PAVEMENT SURFACE
CUPGA
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NOVEMBER 2007
THIN SURFACINGS TO RESTORE
FRICTIONAL CHARACTERISTICS
JEGEL
MICRO-SURFACING TO IMPROVE TAXIWAY SURFACE CONDITION
AND FRICTIONAL CHARACTERISTICS
CFB COLD LAKE
CUPGA
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NOVEMBER 2007
THIN SURFACINGS TO RESTORE
FRICTIONAL CHARACTERISTICS
JEGEL
CLOSEUP OF RUNWAY MICROSURFACING
QUEBEC AIRPORT
CUPGA
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NOVEMBER 2007
LOW INITIAL FRICTION FOR SOME SURFACE COURSE
HMA TYPES WITH THICK ASPHALT BINDER FILMS
SOME SMA AND OGFC FOR INSTANCE
CURRENT ASPHALT TECHNOLOGY ISSUE IN ONTARIO BEING
STUDIED BY MTO/OHMPA WITH THE LEADERSHIP OF KAI TAM
TRUE GRIT
WHITE SMA? YES – AND ITS FRICTIONAL TOO
GRITTING (SANDING WITH FRICTIONAL FINE AGGREGATE) IS USED ON GERMAN SMA
(VERY HIGH ASPHALT BINDER CONTENTS) PRIOR TO TRAFFIC USE. THIS GRITTING
ENHANCES THE INITIAL FRICTION
HMAT JANUARY/FEBRUARY 2004
CUPGA
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NOVEMBER 2007
LOW INITIAL FRICTION CONTINUED
IN THEIR 1991 CTAA PAPER – DEVELOPMENT OF STONE MASTIC MIXES FOR ONTARIO
USE – CARRICK, MACINNES, DAVIDSON, SHENK AND EMERY INDICATED “AFTER
PLACEMENT AND COMPACTION, SMA HAS A COARSE (OPEN) SURFACE TEXTURE
CHARACTERIZED BY GOOD COARSE AGGREGATE MACROTEXTURE (LARGE, ROUGH,
DEPRESSIONS) THAT PROVIDE EXCELLENT FRICTIONAL PROPERTIES (‘SKID’
RESISTANCE) OVER TIME. HOWEVER, WITH THE RICH MASTIC INVOLVED, THERE MAY BE
A PERIOD OF TRAFFIC ACTION REQUIRED TO WEAR THE BINDER FILM OFF THE COARSE
AGGREGATE IN ORDER TO DEVELOP MICROTEXTURE. IF THIS IS OF CONCERN, AN
ASPHALT CEMENT PRE-COATED SAND OR HOT SAND APPLICATION CAN BE USED TO
PROVIDE ENHANCED FRICTIONAL PROPERTIES UNTIL MICROTEXTURE IS DEVELOPED.”
IN THE UNITED KINGDOM, THERE ARE ALSO CONCERNS WITH LOW INITIAL
FRICTION WITH THICK BINDER FILMS (SMA FOR INSTANCE)
GRIT IS USED TO ENHANCE THE EARLY FRICTION (TRL, 1998)
THERE IS ALSO RESEARCH IN PROGRESS ON DRY FRICTIONAL
CHARACTERISTICS (BULLAS, FOR INSTANCE)
IN FRANCE, A MICRO-INCRUSTATION PROCESS HAS BEEN DEVELOPED TO
IMPROVE THE EARLY LIFE FRICTION (SETRA, 2007)
THICK BINDER FILM
COARSE
AGGREGATE
PARTICLE
THICK BINDER FILM
MICRO-INCRUSTATION MATERIAL
COARSE
AGGREGATE
PARTICLE
CUPGA
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NOVEMBER 2007
ASPHALT PAVEMENTS
•
•
•
•
•
STRONG
DURABLE
SMOOTH
ECONOMIC
SECURE
• SAFE
QUESTIONS?
COURTESY OF EJL
ANY USE OF THE INFORMATION PROVIDED IS SUBJECT TO THE USER CAREFULLY EVALUATING ITS
APPLICABILITY TO THE SPECIFIC SITUATION AND CONDITIONS INVOLVED
DARPA URBAN CHALLENGE
DRIVERLESS ROBOTIC CARS
STANFORD’S JUNIOR CAME SECOND IN 2007
STANFORD’S STANLEY CAME FIRST IN THE DESERT CHALLENGE IN 2005