Pavement Design Tools & Pavement Design Tools & Their Relevance to Their Relevance to Canadian AirportsCanadian Airports

Susan Tighe, Ph.D, P.EngSusan Tighe, Ph.D, P.EngCanada Research Chair in Pavement Canada Research Chair in Pavement

& Infrastructure Management& Infrastructure ManagementAssociate ProfessorAssociate Professor

Civil EngineeringCivil EngineeringUniversity of WaterlooUniversity of Waterloo

2007 SWIFT Conference, CAPTG Workshop2007 SWIFT Conference, CAPTG WorkshopCalgary, ABCalgary, AB

September 16, 2007September 16, 2007

AcknowledgementsAcknowledgements

Leanne Whiteley, University of WaterlooLeanne Whiteley, University of Waterloo

Greater Toronto Airports AuthorityGreater Toronto Airports Authority

Natural Science & Engineering Research Natural Science & Engineering Research Council of CanadaCouncil of Canada

Presentation OutlinePresentation OutlineIntroductionIntroductionBackground: Airport Pavement DesignBackground: Airport Pavement DesignAirport Design ToolsAirport Design ToolsRelevance to Canadian AirportsRelevance to Canadian AirportsConclusionsConclusionsQuestionsQuestions

Introduction: DesignIntroduction: DesignPavement ThicknessPavement ThicknessFreezing Index (FI)Freezing Index (FI)Mean Annual Average Mean Annual Average Temperature (MAAT)Temperature (MAAT)Subgrade TypeSubgrade TypeDesign AircraftDesign AircraftWheel LoadWheel LoadMaximum Gross WeightMaximum Gross WeightMaximum TakeMaximum Take--Off WeightOff WeightTire Contact AreaTire Contact AreaConstruction ConstraintsConstruction Constraints

Design Aircraft?

RESEARCHRESEARCH

WorkingWorking

ResearchResearch

Management LoopManagement Loop

LoopLoop

DATA BASEDATA BASE

Component Activities and DecisionsComponent Activities and Decisions

Planning andPlanning andProgrammingProgramming

DesignDesign ConstructionConstruction MaintenanceMaintenance InIn--ServiceServiceEvaluationEvaluation

IntroductionIntroduction

IntroductionIntroductionENVIRONMENTENVIRONMENT

LOADINGLOADING

CONSTRUCTIONCONSTRUCTION

STRUCTURESTRUCTURE

MAINTENANCEMAINTENANCE

Measure(s)Measure(s)ofof

ServiceabilityServiceabilityoror

DeteriorationDeterioration

LayerLayerThicknessesThicknessesLayer TypesLayer Types& Properties& Properties

VariationsVariationsin Thicknessin Thickness& Properties& Properties

SubgradeSubgrade TypeType& Properties& Properties

MoistureMoisture

RadiationRadiation

TemperatureTemperature(Min., Max,(Min., Max,

00 Days, etc.)Days, etc.)Freeze-thawFreeze-thaw

CyclesCycles

LoadsLoadsTire TypesTire Types& Pressures& Pressures

TreatmentsTreatmentsSpacing,Speed,Speed,RepetitionsRepetitions MethodsMethods

QualityQualityTimingTiming

TimingTiming

MethodsMethodsAs-Built QualityAs-Built Quality

VarianceVariance

AgeAge

Flexible Design MethodsFlexible Design Methods

Transport Canada (TC)Transport Canada (TC)Federal Aviation Administration Federal Aviation Administration (FAA) CBR Method(FAA) CBR MethodFAA Layered Elastic Design FAA Layered Elastic Design (LEDFAA)(LEDFAA)Asphalt Institute SWAsphalt Institute SW--11Australian Airport Pavement Australian Airport Pavement Structural Design System (APSDS) Structural Design System (APSDS)

BackgroundBackground

Transport Canada/Public Works airport Transport Canada/Public Works airport pavement design based onpavement design based on–– Frost protectionFrost protection

Freezing Index Freezing Index minimum depth of pavement structureminimum depth of pavement structure

–– Gear loadingGear loadingAircraft structural flexible design charts Aircraft structural flexible design charts pavement pavement equivalent granular thicknessequivalent granular thicknessAircraft structural rigid design charts Aircraft structural rigid design charts concrete slab concrete slab thicknessthickness

ASGASG--19, TC/PW19, TC/PW

INPUTSINPUTSFreezing IndexFreezing IndexSubgrade bearing Subgrade bearing strength/surface strength/surface bearing modulusbearing modulusAircraft (weight, tire Aircraft (weight, tire pressure, % on main pressure, % on main gear)gear)

OUTPUTSOUTPUTSFLEXIBLE: Pavement FLEXIBLE: Pavement equivalent granular equivalent granular thickness, tthickness, t

SWSW--1, Asphalt Institute 1, Asphalt Institute

INPUTSINPUTSMean annual air Mean annual air temperaturetemperatureAircraft typeAircraft typeMovements in design Movements in design periodperiodSubgrade strength Subgrade strength measuremeasure

OUTPUTSOUTPUTSRequired thickness of Required thickness of new HMA pavementnew HMA pavement

APSDS, MINCAD (Australia)APSDS, MINCAD (Australia)

INPUTSINPUTSTrafficTrafficWander statisticsWander statisticsLayered system Layered system (material, thickness (material, thickness and strength)and strength)

OUTPUTSOUTPUTSMaterial type (asphalt Material type (asphalt vs. subgrade)vs. subgrade)Maximum damage Maximum damage values (damage factor values (damage factor & critical strain) for & critical strain) for each aircrafteach aircraftMaximum of total Maximum of total damagedamage

LEDFAA , FAALEDFAA , FAA

INPUTSINPUTSPavement structure Pavement structure propertiesproperties–– Layer materialLayer material–– Layer thicknessLayer thickness–– Layer strengthLayer strength

Aircraft propertiesAircraft properties–– gross taxi weightgross taxi weight–– annual departuresannual departures–– % annual growth% annual growth

OUTPUTSOUTPUTSSurface, base, Surface, base, subbase, subgrade subbase, subgrade –– ThicknessThickness–– ModulusModulus–– Poisson’s RatioPoisson’s Ratio–– StrengthStrength

Aircraft CDF Aircraft CDF contribution, CDF Max contribution, CDF Max for Aircraftfor Aircraft

Equivalent Granular ThicknessEquivalent Granular Thickness

Granular Base Equivalency (GBE) is a measure Granular Base Equivalency (GBE) is a measure expressing the contribution of each pavement expressing the contribution of each pavement component of an equivalent thickness of granular component of an equivalent thickness of granular basebase

TAC, 1997

ComponentComponent Thickness (mm)Thickness (mm) GBEGBEAsphalt concreteAsphalt concrete 100100 100 x 2 = 200100 x 2 = 200Crushed baseCrushed base 250250 250 x 1 = 250250 x 1 = 250Granular baseGranular base 500500 500 x 1 = 500500 x 1 = 500Total thicknessTotal thickness 850850 EGT = 950EGT = 950

Design Method InputsDesign Method Inputs

Design MethodDesign Method ClimateClimate TrafficTrafficSubgradeSubgradeStrengthStrength

TCTC XX** XX1,21,2 XXFAAFAA XX** XX22 XXLEDFAALEDFAA XX XXSWSW--11 XX**** XX22 XXAPSDSAPSDS XX XX

* Freezing Index * Freezing Index ** ** Mean Average Air TemperatureMean Average Air Temperature11 No volume consideration No volume consideration 2 2 Design aircraft concept Design aircraft concept

AirportAirportDesign InputsDesign InputsToronto (YYZ)Toronto (YYZ) Waterloo (YKF)Waterloo (YKF)

FI (FI (ooCC--days)days) 598598 711711

MAAT (MAAT (ooC)C) 1010 7.27.2

TrafficTraffic AircraftAircraft A330A330--300, A340300, A340--300,300,A340A340--500/600, 500/600, B747B747--400, 400, B777B777--200ER,200ER,B777B777--200LR,200LR,B777B777--300ER, 300ER, LL--10111011--500500MDMD--1111

A320A320--200, BAe200, BAe--146146--100,100,Challenger, Dash 8, Challenger, Dash 8, Cessna 152, 172, 210,Cessna 152, 172, 210,650, 650, ConvairConvair 440,440,Falcon, DCFalcon, DC--4,4,GulfstreamGulfstream,,LearjetLearjet, Piper Seminole,, Piper Seminole,Saab 340Saab 340

SurfaceSurface 125 mm AC125 mm AC 100 mm AC100 mm AC

BaseBase 300 mm Granular A300 mm Granular A 300 mm Granular A300 mm Granular A

SubbaseSubbase 900 mm Granular B900 mm Granular B 340 mm Granular B340 mm Granular B

SubgradeSubgrade CBR=4.5, S=77.75CBR=4.5, S=77.75 CBR=4.5, S=77.75CBR=4.5, S=77.75

Material Material LayersLayers

ClimateClimate

Design InputsDesign Inputs

FlexibleFlexibleFlexible

-50%

-30%

-10%

10%

30%

50%TC

/PW

SW

-1

APS

DS

LEDF

AA

TC/P

W

SW

-1

APS

DS

LEDF

AA

YYZ YFK

Airport & Method

Equi

vale

nt G

ranu

lar

Thic

knes

s Re

lativ

e to

TC

/PW

Toronto (YYZ) Toronto (YYZ) -- FlexibleFlexible

YYZ - Flexible

-50%

-30%

-10%

10%

30%

50%

TC/PW SW-1 APSDS LEDFAA

Method

Equi

vale

nt G

ranu

lar

Thic

knes

s R

elat

ive

to

TC/P

W

CBR=3 CBR=4 CBR=4.5 CBR=5 CBR=6

Waterloo (YKF) Waterloo (YKF) -- FlexibleFlexible

YKF - Flexible

-50%

-30%

-10%

10%

30%

50%

TC/PW SW-1 APSDS LEDFAA

Method

Equi

vale

nt G

ranu

lar

Thic

knes

s Re

lativ

e to

TC

/PW

CBR=3 CBR=4 CBR=4.5 CBR=5 CBR=6

Sources of DataSources of Data20%

0%

13%

20%13%

34%AltanticQuebecOntarioPrairiePacificNorthern

60%13%

7%

7%

13%

National Airport SystemRegional/ LocalArcticRemoteUnclassified

Airport Region

Airport Type

Within Program Sensitivity AnalysisWithin Program Sensitivity Analysis

Subgrade StrengthSubgrade Strength–– California Bearing Strength California Bearing Strength

(CBR)(CBR)ClimateClimate–– Freezing Index (FI)Freezing Index (FI)–– Mean Annual Average Mean Annual Average

Temperature (MAAT)Temperature (MAAT)

TrafficTraffic–– Aircraft CharacteristicsAircraft Characteristics

Maximum Gross Maximum Gross Weight (MGW)Weight (MGW)Maximum TakeMaximum Take--Off Off Weight (MTOW)Weight (MTOW)Wheel LoadWheel LoadTire Contact AreaTire Contact Area

–– Aircraft Volume Aircraft Volume ((% annual growth)% annual growth)

Sample sensitivity analysis Sample sensitivity analysis EGT vs. MGW for TC flexibleEGT vs. MGW for TC flexible

Transport Canada Flexible

0250500750

1000125015001750

0 1000 2000 3000 4000

Design Aircraft Maximum Gross Weight (kN)

Equi

vale

nt

Gra

nula

r Th

ickn

ess

(mm

)

Very Low Low Medium High

(Very Low ) (Low ) (Medium) (High)

Asphalt Cement = 2 GBE Granular Base = 1 GBE Asphalt Cement = 2 GBE Granular Base = 1 GBE

GBE=Granular Base EquivalencyGBE=Granular Base Equivalency

Between Program Data AnalysisBetween Program Data Analysis

Variation significanceVariation significance

Airport specific thickness vs. design Airport specific thickness vs. design method analysismethod analysis

Airport specific design method relative Airport specific design method relative comparison comparison

Sample Sample –– Variation SignificanceVariation Significance

Flexible EGTFlexible EGTTC vs. TC vs.

Method VariabilityMethod VariabilitySignificanceSignificance

TCNFTCNF aa

FAAFAA rr

LEDFAALEDFAA aa

FEDFAAFEDFAA aa

SWSW--11 aa

APSDSAPSDS rr

aa denotes significant variability at a 95% confidence level denotes significant variability at a 95% confidence level rr denotes no significant variability at a 95% confidence leveldenotes no significant variability at a 95% confidence level

Sample Sample –– Airport vs. Design MethodAirport vs. Design Method

Very

Low

Low

Med

ium

Stro

ng

0

7.50

5001000

1500

2000

2500

Equivalent Granular

Thickness (mm)

CBR

% Annual Growth

LEDFAA Flexible - Toronto ON

Between Program Flexible ResultsBetween Program Flexible Results

SubgradeSubgrade strength & strength & annual growthannual growth

statistically significantstatistically significant

Change inChange in subgradesubgradestrength more significant strength more significant than an in traffic of up than an in traffic of up to 10%to 10%

TC with frost protection & TC with frost protection & FAA with stabilized base FAA with stabilized base

most conservative most conservative flexible pavement structureflexible pavement structure

LEDFAA & FAA with LEDFAA & FAA with stabilized base most stabilized base most closely relate to TC flexible closely relate to TC flexible design outputdesign output

ConclusionsConclusions

Layer thicknesses increase as CBR Layer thicknesses increase as CBR values decreasevalues decreaseSWSW--1 & APSDS are generally more 1 & APSDS are generally more conservative for large airports than conservative for large airports than TC/PWTC/PWSWSW--1 & APSDS are less conservative 1 & APSDS are less conservative for small airports than TC/PWfor small airports than TC/PW

ConclusionsConclusionsThe FAA flexible pavement thickness The FAA flexible pavement thickness increases dramatically once the increases dramatically once the subgradesubgrade is is reduced to a CBR of 6 (weak reduced to a CBR of 6 (weak subgradesubgradestrength)strength)

FAA flexible = f (design aircraft maximum FAA flexible = f (design aircraft maximum gross weight)gross weight)

LEDFAA, FEDFAA, SWLEDFAA, FEDFAA, SW--1, APSDS more 1, APSDS more sensitive to sensitive to subgradesubgrade (vs. traffic)(vs. traffic)

RecommendationsRecommendationsGeometric design analysisGeometric design analysis–– impact on pavement design and performanceimpact on pavement design and performance

Comparison new design methods (FAARFIELD)Comparison new design methods (FAARFIELD)

New stateNew state--ofof--the art designs do not necessarily account the art designs do not necessarily account for the climatic conditions experienced in Canadafor the climatic conditions experienced in Canada

Incorporate economic analysis into the design and Incorporate economic analysis into the design and planning stageplanning stage

Thank you/ MerciThank you/ Merci

Questions?Questions?

Susan Tighe, Susan Tighe, sltighesltighe@@uwaterloouwaterloo.ca.ca