AN ANALYSIS OF THE SEASONAL AND SHORT-TERM VARIATION OF PAVEMENT SKID RESISTANCE.pdf

An Analysis of the Seasonal and Short-Term Variation ofRoad Pavement Skid Resistance By: Douglas James Wilson Department of Civil and Environmental Engineering A Thesis submitted in fulfilment of the requirementsfor the degree of Doctor of Philosophy in Engineering, The University of Auckland May 2006 i ABSTRACT It has been well proven that as the skid resistance of a road surfacing decreases, the number of loss of control type crashes increases, causing road death and injuries.However, the management of skid resistance of road surfacings continuestobedifficultduetotheinherentandsometimesrandomvariationinskidresistancelevelsovertime.Thisstudyisaninvestigationandanalysisofseasonalandshorttermvariationofmeasuredskidresistanceintwo phases. Phase1:RegularfieldmonitoringwasundertakenusingtheGripTesterandtheDynamicFrictionTester measurement devices on seven sites in the Auckland and Northland Regions of New Zealand was undertaken over a threeyearperiod.Theeffectsoftemperature,rainfall,contaminants,newsurfacings,geometricelementsand aggregatepropertieswereanalysedtoinvestigatefactorsthatinitiatechangesinthemeasuredskidresistanceof pavement surfacings. Phase 2: Laboratory prepared samples were constructed for accelerated polishing and skid resistance testing of four differentaggregates(twogreywackes,abasaltandanartificialiron-makingmelterslagaggregate).Thesamples werepolishedinanacceleratedpolishingmachinetoanequilibriumskidresistancelevel(Stage1polishing).Contaminantswerethenaddedtotheacceleratedpolishingprocesstodeterminetheeffectofvaryingadditive, particle size and hardness in an attempt to simulate seasonal and/or short-term variations that occur in the field. Theresultshavedemonstratedthatsignificantandpreviouslyunpredictablevariations(greaterthan30%)in measured skid resistance can occur over short time periods.These variations cannot be explained by any one factor. They are the result of a number of inter-related factors, including the geological properties of the aggregates and the contaminantsthemselves,thepreviousrainfallhistory,theroadgeometry,thecalendarmonthoftheyearand (dependinguponthemeasurementdevice),thetemperatureduringtesting.Thelaboratorytestsdemonstratethat acceleratedpolishingtestsofaggregatesamplescouldbepreparedfortestingbytheDynamicFrictionTesterand that significant variations in measured skid resistance could be simulated on various aggregates in the laboratory by the addition of contaminants.The results of the testing and addition of contaminants on various aggregates resulted in significant behavioural differenceswhichwere related to the geological properties of the aggregates themselves, as well as the contaminants used in the accelerated polishing process.Thefindingsoftheresearchhavespecificrelevancetothreeareasofindustry;RoadControllingAuthoritieswho areprimarilyinterestedinskidresistancepolicy,standardsandmanagement,RoadAssetManagerswhooperate, maintain and manage condition level and the safety aspects of the road network and Crash Investigators who collect andanalysecrashdataprimarilyforlegalproceedings.Allthreeoftheseindustryorganisationsneedtoclearly understandtheinherentvariabilityofskidresistance,thefactorsinvolvedandtheeffectsthatgeologicaland environmental variations have on skid resistance measurement. ii ACKNOWLEDGMENTS Balancing duties of being anacademic staffmemberwhilst undertaking a doctoral programme of researchwith an ever patient, although sometimes a family in-waiting is a difficult task.I am certainly pleased that the light at the endofthetunnelhasindeedturnedintodaylightandnotanoncomingtrain.Itistherefore,withgreatpleasure thatIbeginwithacknowledgementstothosethathavecontributedinsomanywaystotheculminationofmany yearsofresearchtothethesis.Igratefullyacknowledgethehelpofmany,howevertonamethemallinsome logicalprioritisedorderisdifficult.Aftermuchdeliberation,Ihavedecidedtoorderacknowledgementsinthree particularareasbeingUniversity,industrysupportandpersonal;howeverthesecategoriesarenotgiveninany prioritised order. University of Auckland: This research was carried out under the supervision of Associate Professor Roger C. M. Dunn (main supervisor) and ProfessorBruceW.Melville(HeadofCivilandEnvironmentalEngineeringDepartment)towhomIexpressmy sincere appreciation for all their guidance, encouragement and general advice throughout.As both Roger and Bruce are also academic colleagues, their guidance has also been valued through the research programme.SpecialacknowledgementmustalsogotoNoelPerinpanayagamwhohastirelesslyworkedonthedatacollection side aspect of this research including looking after and calibrating the testing equipment.Noel has always been very obliging and his happy disposition alwaysmakes him a pleasure toworkwith.Acknowledgement is alsogivento GaryCarrforelectronicsexpertisewhenitwasrequiredandothercontractstaffandsummerstudentswhohave helped with the data collection programme.This includes, Louis Sky Bargh, Malcolm Dunn, Subodh Gidh, Lei Wu, Wendy Chan, Vincent Tang and Caleb Phang.I would also like to acknowledge The University of Auckland Faculty of Engineering and the Dean of Engineering (ProfessorPeterBrothers)whohavesupportedtheresearchprogrammeandhaveinvestedsignificantinternal research funds, primarily to purchase the skid testing equipment necessary to undertake this research project. MythanksisalsogiventomycolleaguesDrNareshSinghalandDrTakisElefsiniotiswhohelpedadviseand superviseWeiLi(William)whoundertookthebulkoftheenvironmentalanalysisofthecontaminantsamples collected from the road surface.This aspect formed part of a student research project in the Department of Civil and Environmental Engineering Laboratory.Thanks is also given to Dr Bill Flinn for the numerous dicussions that we have had regarding data analysis and statistics. AppreciationisalsogiventoProfessorPhilippaBlackoftheUniversityofAucklandGeologyDepartment,who undertookgeologicaltestsandgavegeologicalinterpretationsoftheeffectsofacceleratedpolishingonthe aggregate surfaces. Industry Support: AcknowledgementisgiventomembersoftheAdvisoryCommitteethatwereexternaltotheUniversityfortheir adviceandcomments,consistingofBarryGundersen,DrBryanPidwerbesky,DrDavidHutchison,DrJohn Yeaman, Mark Owen and Peter Cenek. Specificappreciation(asoutlinedbelow)isgiventothesignificantindustrypartners/supportersthathavehelped support the research in many different ways. iii Firstly,ImustgivespecialthankstoWorksInfrastructureLimitedwhohavesupportedtheresearchboth financially and with resources almost from the outset of the research programme.The field testing data collection in theNorthlandRegionofNewZealandwouldnothavebeenpossiblewithoutthesupportoftheWhangareiWorks Infrastructure team which included Peter Houba, Peter King, Matthew Findlay, Glen Kirk and the temporary traffic controlteamheadedbyDerekPhillips.ThanksalsogototheAucklandWorksInfrastructuretestinglaboratory whichsuppliedaggregatesuppliesforlaboratorysamplingandtestingandwhosetechniciansalsoundertook Polished Stone Value tests on the aggregatesamples.Special thanks are also given to Michael Haydon and David Hutchisonfromthe technicalmanagement team of Works Infrastructurewhohave always beenwilling to listen to my requests and the many discussions that we have had on aspects of skid resistance, policy and technical matters.Further acknowledgement is given to David Hutchison who has willingly waded through a draft of the thesis giving very useful technical and editing feedback.Pavement Management Services and especially Dr John Yeaman and Daniel Rich for their support for the research programmefromthebeginning,andsecondlyforfinanciallycontributingtothepurchaseoftheDynamicFriction Tester for the static field testing and the laboratory tests. AchnowledgementisalsogiventoThePortsofAucklandandespeciallyJoCampbelloftheAXISIntermodal group that allowed access to the rail grid site as a field-testing site outside of normal port operation hours. TransitNewZealandheadofficestaff(MarkOwen,DavidCookandChrisParkman)arealsothankedfortheir support of the research and in enabling access to historic SCRIM and RAMM data on the Transit New Zealand state Highway network.LandTransportNewZealand(formerlyTransfundNewZealand)areacknowledgedfortheirsignificantfinancial support of the research, in terms of the Land Transport New Zealand Research project that allowed the field research datacollectionandanalysisprogrammetocontinueforafurtheryearandfortheextensiontothecontrolled laboratory testing. Personal: And to the last and most important, to my special family whom I wholeheartedly want to thank and acknowledge as being so significantly important in the culmination of this thesis.To Puti who has advised on many occasions with regardstostatisticsandwhohasencouragedandcaredforahusbandwhohas,attimesIadmit,gottiredand grumpy and who has, especially in more recent months, not always been there.For Miriama and James, who for alloftheirliveshaveputupwithadadandhiswritingofaboringthesiswithtoomanywordsandnotenough pictures.To Miriama, for your joy and laughter and James, for your special cuddles even throughout all your trials, pain and ill-health; you have inspired me to persevere against all odds.To my parents of both lineages for their encouragement and especially to my mother Elayne who worked through a draftofthethesisandwhohelpededitpointsandrulesofgrammarandEnglishthatinsomecasesIhadlong forgotten. iv TABLE OF CONTENTS ABSTRACT................................................................................................................................................................... i ACKNOWLEDGMENTS ............................................................................................................................................ ii TABLE OF CONTENTS............................................................................................................................................. iv LIST OF FIGURES ..................................................................................................................................................... ix LIST OF TABLES..................................................................................................................................................... xiii ABBREVIATIONS AND ACRONYMS .................................................................................................................. xiv 1INTRODUCTION ................................................................................................................................................ 1 1.1Overview ........................................................................................................................................................ 1 1.2Road Safety, Risk and Policy ......................................................................................................................... 1 1.3The Variability of Skid Resistance ................................................................................................................. 2 1.4Terminology ................................................................................................................................................... 3 1.5Research Objectives........................................................................................................................................ 3 1.6Research Methodology ................................................................................................................................... 4 1.7Organisation of the Thesis .............................................................................................................................. 4 2SKID RESISTANCE FUNDAMENTALS........................................................................................................... 7 2.1Introduction .................................................................................................................................................... 7 2.2Function and Characteristics of Road Surfacings ........................................................................................... 7 2.2.1Introduction........................................................................................................................................... 7 2.2.2Infrastructure Asset Management Goals ............................................................................................... 7 2.2.3Monitoring Surface Characteristics and Performance........................................................................... 8 2.2.4Pavement Deterioration Modelling in New Zealand (NZ dTIMS System) ........................................... 8 Background..................................................................................................................................................... 8 The Need for Predictive Modelling ................................................................................................................ 9 Components of Predictive Modelling ........................................................................................................... 10 Pavement Deterioration Modelling and Road Asset Management ............................................................... 11 The NZ dTIMS System and Skid Resistance................................................................................................ 13 2.3The Traffic System and Road Safety............................................................................................................ 15 2.3.1Introduction......................................................................................................................................... 15 2.3.2Road Crash Factors ............................................................................................................................. 15 2.3.3Skid Resistance and Crash Risk.......................................................................................................... 18 Introduction .................................................................................................................................................. 18 Before and After Studies............................................................................................................................... 18 Comparison with Norm Studies.................................................................................................................... 18 Regression Studies........................................................................................................................................ 20 Summary of Recent Crash Risk Research .................................................................................................... 21 2.3.4Skid Resistance Standards................................................................................................................... 23 Introduction .................................................................................................................................................. 23 UK based Standards of Skid Resistance ....................................................................................................... 24 New Zealand Standards of Skid Resistance.................................................................................................. 26 Level of Skid Resistance and the Road User ................................................................................................ 27 2.4Vehicle System Dynamics ............................................................................................................................ 27 2.4.1Introduction......................................................................................................................................... 27 2.4.2Driving Dynamic Fundamentals ......................................................................................................... 28 2.5Definitions of Skid Resistance and Friction ................................................................................................. 29 2.5.1Introduction......................................................................................................................................... 29 2.5.2Components of Friction....................................................................................................................... 29 2.5.3The Dynamics of Friction Forces........................................................................................................ 31 2.5.4Braking and Friction............................................................................................................................ 36 2.5.5Crash Investigations and Braking Distances ....................................................................................... 37 3FACTORS AFFECTING ROAD SURFACE SKID PROPERTIES.................................................................. 39 3.1Introduction .................................................................................................................................................. 39 3.2Road Pavement Surface Texture profiles...................................................................................................... 39 3.2.1Introduction......................................................................................................................................... 39 3.2.2Microtexture........................................................................................................................................ 41 3.2.3Macrotexture ....................................................................................................................................... 41 3.2.4Surface Texture, Friction and Speed ................................................................................................... 42 3.3Aggregate Properties .................................................................................................................................... 43 v 3.3.1Introduction......................................................................................................................................... 43 3.3.2Petrological types of Aggregates used in Pavement Construction ...................................................... 44 3.3.3Desirable properties of Aggregates for Bituminous Surfacings .......................................................... 44 3.3.4Abrasion of Aggregates....................................................................................................................... 45 3.3.5Polishing of Aggregates ...................................................................................................................... 46 3.3.6Differential Wearing of Aggregates .................................................................................................... 49 3.3.7Weathering.......................................................................................................................................... 49 3.3.8Summary of Aggregate Sources appropriate for Surfacings ............................................................... 49 3.3.9Aggregate Size, Shape and Spacing.................................................................................................... 50 3.4Loading factors ............................................................................................................................................. 50 3.4.1Traffic Intensity and Surface Age ....................................................................................................... 50 3.4.2Road Site and Traffic Flow Conditions............................................................................................... 53 3.5Environmental Effects on Skid Resistance ................................................................................................... 54 3.5.1Introduction......................................................................................................................................... 54 3.5.2Water Film Thickness ......................................................................................................................... 54 3.5.3Drainage Conditions............................................................................................................................ 57 3.5.4Surface Contamination........................................................................................................................ 57 3.5.5Temperature ........................................................................................................................................ 60 3.5.6Seasonal Variations ............................................................................................................................. 61 3.5.7Short-Term Variations......................................................................................................................... 64 4SKID RESISTANCE TESTING METHODS AND MODELS.......................................................................... 68 4.1Introduction .................................................................................................................................................. 68 4.2Testing Device Factors ................................................................................................................................. 68 4.2.1Introduction......................................................................................................................................... 68 4.2.2Vehicle Speed...................................................................................................................................... 68 4.2.3Tyre Angle .......................................................................................................................................... 69 4.2.4Wheel Slip Ratio ................................................................................................................................. 69 4.2.5Tyre Characteristics............................................................................................................................. 69 Development of Modern Tyres..................................................................................................................... 69 Tyre Construction Effects............................................................................................................................. 70 Tyre Tread Design ........................................................................................................................................ 71 Tyre Tread Pattern........................................................................................................................................ 72 Tyre Tread Compound.................................................................................................................................. 74 Tyre Tread Wear Irregularity........................................................................................................................ 77 Developments in Tyre Design ...................................................................................................................... 77 4.2.6Tyre Contact area and Stress ............................................................................................................... 78 Contact Area ................................................................................................................................................. 78 Distribution of Contact Stress....................................................................................................................... 78 4.3Measuring Surface Friction .......................................................................................................................... 81 4.3.1Introduction......................................................................................................................................... 81 4.3.2Sideways Force Method...................................................................................................................... 83 4.3.3Braked Wheel Method ........................................................................................................................ 86 GripTester..................................................................................................................................................... 86 Electronic Recording Decelerometer ............................................................................................................ 87 Norsemeter Road Analyser and Recorder- ROAR .................................................................................. 88 Locked Wheel Pavement Friction Tester...................................................................................................... 90 4.3.4British Pendulum Method ................................................................................................................... 91 4.3.5The Dynamic Friction Tester .............................................................................................................. 92 4.3.6Systems for On-board Measurement of Tyre-Pavement Friction........................................................ 94 4.4Laboratory-based Surface Friction Prediction Methods ............................................................................... 95 4.4.1Introduction......................................................................................................................................... 95 4.4.2The Polished Stone Value (PSV) Test................................................................................................. 95 Introduction .................................................................................................................................................. 95 The Polished Stone Value Test Procedure.................................................................................................... 96 A critical evaluation of the PSV Test ........................................................................................................... 97 PSV Test Summary....................................................................................................................................... 99 4.4.3Profiling and Imaging Techniques for Assessing Aggregate Microtexture....................................... 100 4.4.4Automatic Image Analysis ................................................................................................................ 101 4.5Measuring Macrotexture............................................................................................................................. 101 4.5.1Introduction....................................................................................................................................... 101 4.5.2Volumetric Texture Method.............................................................................................................. 101 4.5.3Laser Profile Method......................................................................................................................... 102 4.5.4Outflow Method................................................................................................................................ 104 vi 4.6Models of Skid Resistance.......................................................................................................................... 104 4.6.1Introduction....................................................................................................................................... 104 4.6.2Polished Stone Value Empirical Model ............................................................................................ 105 4.6.3The Penn State Model ....................................................................................................................... 108 4.6.4The Rado Model................................................................................................................................ 110 4.6.5Seasonal and Short-Term Variation Models ..................................................................................... 111 4.6.6The PIARC Model and the International Friction Index................................................................... 113 4.6.7Goldens Model................................................................................................................................. 115 4.6.8Neural Networks to Model Skid Resistance...................................................................................... 115 5THE EXPERIMENTAL DESIGN.................................................................................................................... 117 5.1Introduction ................................................................................................................................................ 117 5.2The Hypothesis ........................................................................................................................................... 117 5.3Research Methodology ............................................................................................................................... 118 5.4Field Test Site Characteristics .................................................................................................................... 119 5.5Field Test frequency ................................................................................................................................... 121 5.6Field Test Equipment and Standard Test conditions................................................................................... 122 5.6.1Continuous Skid Resistance (microtexture) Measurements .............................................................. 122 5.6.2Standard Skid Resistance Field Test Procedures............................................................................... 123 5.6.3Stationary Skid Resistance Tests....................................................................................................... 123 5.6.4Macrotexture Measurements ............................................................................................................. 124 5.7Field Test Sites ........................................................................................................................................... 125 5.7.1Tamaki Campus (University of Auckland) site................................................................................. 127 5.7.2Ports of Auckland site ....................................................................................................................... 128 5.7.3Kaiwaka Site (SH 1N)....................................................................................................................... 130 5.7.4Brynderwyn Site (SH 1N) ................................................................................................................. 130 5.7.5Hikurangi Site (SH 1N)..................................................................................................................... 131 5.7.6Kara Road Site (SH 14)..................................................................................................................... 132 5.7.7Snooks - Tatton Site (SH 14) ............................................................................................................ 133 5.8Surface Detritus and Skid Resistance ......................................................................................................... 134 5.8.1Introduction....................................................................................................................................... 134 5.8.2Detritus Sample Collection Method.................................................................................................. 134 5.8.3Detritus Laboratory Analysis Methods ............................................................................................. 135 5.9Laboratory Based Polishing Methodology ................................................................................................. 136 5.9.1Introduction....................................................................................................................................... 136 5.9.2The experimental variables ............................................................................................................... 137 5.9.3Laboratory Surface Samples ............................................................................................................. 138 5.9.4Laboratory-based Texture Measurement........................................................................................... 139 5.9.5An Accelerated Polishing Machine................................................................................................... 139 5.9.6Laboratory Procedures for Polishing and Skid Resistance Measurement ......................................... 142 6SKID RESISTANCE FIELD TESTING RESULTS AND DISCUSSION...................................................... 145 6.1Introduction ................................................................................................................................................ 145 6.2Standard Skid Resistance Field Testing Procedures ................................................................................... 145 6.2.1Introduction....................................................................................................................................... 145 6.2.2GripTester Testing Procedures.......................................................................................................... 146 6.2.3Dynamic Friction Tester Field Procedures........................................................................................ 147 6.3Processing of the Field Test results ............................................................................................................ 148 6.3.1Introduction....................................................................................................................................... 148 6.3.2Processing of Raw GripTester Results .............................................................................................. 148 6.3.3Example Analysis of GripTester Results .......................................................................................... 150 6.3.4Skid resistanceTimeslice Analysis .................................................................................................... 154 6.3.5Processing of Dynamic Friction Test Results ................................................................................... 155 6.3.6Analysis of Dynamic Friction Test Results....................................................................................... 156 6.4Summary Field Site Results........................................................................................................................ 157 6.4.1Introduction....................................................................................................................................... 157 6.4.2Tamaki Campus (University of Auckland) Site ................................................................................ 157 6.4.3Ports of Auckland Site....................................................................................................................... 161 6.4.4Kaiwaka Slag Site ............................................................................................................................. 164 6.4.5Brynderwyn South Curve Site........................................................................................................... 167 6.4.6Hikurangi Site ................................................................................................................................... 170 6.4.7Kara Road Site .................................................................................................................................. 172 6.4.8Snooks Tatton Site ......................................................................................................................... 174 6.5Aggregate PSV and Measured Skid Resistance.......................................................................................... 176 vii 6.5.1Field Testing Summary Discussion................................................................................................... 177 7REPEATABILITY OF SKID RESISTANCE TESTING DEVICES............................................................... 180 7.1Introduction ................................................................................................................................................ 180 7.2GripTester................................................................................................................................................... 180 7.3Dynamic Friction Tester ............................................................................................................................. 184 7.4Temperature Effects on Skid resistance measurement devices................................................................... 187 7.4.1Introduction....................................................................................................................................... 187 7.4.2GripTester ......................................................................................................................................... 188 7.4.3Dynamic Friction Tester.................................................................................................................... 191 7.4.4Summary of Temperature Effects ..................................................................................................... 194 7.5Correlation of Skid Resistance Devices...................................................................................................... 195 7.5.1Introduction....................................................................................................................................... 195 7.5.2Correlation of the GripTester with the DF Tester ............................................................................. 196 7.5.3Correlation of GripTester and SCRIM.............................................................................................. 199 7.5.4Correlation of GripTester and SCRIM by IFI ................................................................................... 201 7.5.5Correlation of GripTester and Dynamic Friction Tester by IFI ........................................................ 204 7.6Christchurch Surface Friction Device Correlation Trials ........................................................................... 204 7.6.1Introduction....................................................................................................................................... 204 7.6.2Main Trial Test Site .......................................................................................................................... 205 7.6.3Reported Results ............................................................................................................................... 206 7.6.4Further Data Analysis........................................................................................................................ 206 7.6.5IFI Transformations .......................................................................................................................... 210 7.7Summary Device Discussion...................................................................................................................... 213 8SEASONAL AND SHORT-TERM VARIATIONS......................................................................................... 214 8.1Introduction ................................................................................................................................................ 214 8.2Seasonal Variation Results ......................................................................................................................... 214 8.2.1Introduction....................................................................................................................................... 214 8.2.2Auckland Asphalt Mix Sites ............................................................................................................. 216 8.2.3Northland State Highway Site Results .............................................................................................. 218 8.2.4Seasonal Variation Summary discussion........................................................................................... 221 8.3Short-Term Variations ................................................................................................................................ 222 8.3.1Introduction....................................................................................................................................... 222 8.3.2Rainfall Data ..................................................................................................................................... 223 8.3.3Rainfall Functions ............................................................................................................................. 225 8.3.4Effects of Rainfall on GripTester Device Measurements.................................................................. 226 8.3.5Effects of Rainfall on SCRIM Device Measurements....................................................................... 231 8.3.6Normalised GripTester Results for Northland Sites and Effects of Rainfall..................................... 234 8.4Effects of Geometric Elements on Skid Resistance.................................................................................... 237 8.4.1Introduction....................................................................................................................................... 237 8.4.2Timeslice Analysis for Geometric Elements on the Kara Road Field Site........................................ 237 8.4.3Summary of Timeslice Analysis on Geometric Elements................................................................. 240 8.5Washing Trials............................................................................................................................................ 240 8.5.1Introduction....................................................................................................................................... 240 8.5.2GripTester Results............................................................................................................................. 241 8.5.3British Pendulum Results .................................................................................................................. 242 8.5.4Washing Trial Conclusions ............................................................................................................... 243 9DETRITUS RESULTS AND DISCUSSION................................................................................................... 244 9.1Introduction ................................................................................................................................................ 244 9.2Sampling Site Details ................................................................................................................................. 244 9.3Suspended Solids and Particle Size Distribution ........................................................................................ 246 9.4Heavy Metals .............................................................................................................................................. 248 9.5Petroleum Hydrocarbons and Organic Carbon ........................................................................................... 249 9.6Summary of Detritus Analysis.................................................................................................................... 250 10LABORATORY POLISHING TEST RESULTS AND DISCUSSION .................................................... 252 10.1Introduction............................................................................................................................................ 252 10.2Geological Properties of the Aggregates................................................................................................ 252 10.2.1Introduction....................................................................................................................................... 252 10.2.2Moutohora Greywacke...................................................................................................................... 253 10.2.3Otaika Greywacke............................................................................................................................. 254 10.2.4Holcim Basalt.................................................................................................................................... 254 viii 10.2.5Melter Slag........................................................................................................................................ 255 10.3Polishing Aggregates to Equilibrium Levels (Stage 1) .......................................................................... 256 10.3.1Introduction....................................................................................................................................... 256 10.3.2Moutohora Greywacke Laboratory Sample ...................................................................................... 258 10.3.3Holcim Basalt Laboratory Sample .................................................................................................... 259 10.3.4Otaika Greywacke Laboratory Sample ............................................................................................. 261 10.3.5Melter Slag Laboratory Sample ........................................................................................................ 262 10.3.6Summary of Stage 1 Accelerated Polishing ...................................................................................... 264 10.4Geological Properties and the Aggregates Resistance to Polishing...................................................... 265 10.4.1Introduction....................................................................................................................................... 265 10.4.2Constituents of the Aggregate Samples............................................................................................. 266 10.4.3A Geological Interpretation of the Polishing of the Sample Aggregates........................................... 267 10.5The Results of Polishing with Contaminants (Stage 2).......................................................................... 268 10.5.1Introduction....................................................................................................................................... 268 10.5.2Contaminant Additives...................................................................................................................... 269 10.5.3Moutohora Greywacke...................................................................................................................... 269 10.5.4Holcim Basalt.................................................................................................................................... 272 10.5.5Otaika Greywacke............................................................................................................................. 274 10.5.6Melter Slag........................................................................................................................................ 276 10.5.7Summary of Stage 2 Accelerated Polishing with Contaminants ....................................................... 279 10.5.8Macro Photographs of the Effects of Polishing with Contaminants.................................................. 282 10.5.9A Geological Explanation of the Stage 2 Polishing Experiments ..................................................... 285 10.6Summary of Controlled Laboratory Experiments .................................................................................. 286 11RESEARCH SUMMARY.......................................................................................................................... 288 11.1Overview................................................................................................................................................ 288 11.2Research Aims and Objectives............................................................................................................... 288 11.3Seasonal and Short-Term Variations of Measured Skid Resistance ...................................................... 289 11.3.1Outline............................................................................................................................................... 289 11.3.2Variations in the Mean Value............................................................................................................ 289 11.3.3Seasonal Variations by Calendar Months of Year............................................................................. 292 11.3.4Short-Term Variations related to Rainfall ......................................................................................... 293 11.4Skid Testing Devices ............................................................................................................................. 294 11.4.1Outline............................................................................................................................................... 294 11.4.2Comparative Device Conclusions ..................................................................................................... 295 11.4.3The Correlation of Devices ............................................................................................................... 296 11.5Timeslice Analysis and Influence of Geometry on Geometric Elements .............................................. 297 11.6Washing Trials ....................................................................................................................................... 298 11.7Samples of Detritus Collected off the Road........................................................................................... 298 11.8Accelerated Polishing Experiments ....................................................................................................... 299 11.8.1Outline............................................................................................................................................... 299 11.8.2Stage 1 Accelerated Polishing........................................................................................................... 300 11.8.3Stage 2 Accelerated Polishing........................................................................................................... 301 11.8.4Summary Conclusions of the Accelerated Polishing Laboratory Experiments................................. 302 11.8.5An Analysis of the Performance of the Polished Stone Value Test .................................................. 302 12FINAL CONCLUSIONS............................................................................................................................ 304 12.1Overview................................................................................................................................................ 304 In-field Skid Resistance Variation: ............................................................................................................. 304 Skid Testing Devices: ................................................................................................................................. 305 Laboratory Tests: ........................................................................................................................................ 305 12.2Relevance of the Research ..................................................................................................................... 305 Road Controlling Authorities...................................................................................................................... 306 Road Asset Managers: ................................................................................................................................ 306 Crash Investigators: .................................................................................................................................... 307 12.3Further Research .................................................................................................................................... 307 Policy and Risk Management: .................................................................................................................... 307 Skid Testing Devices: ................................................................................................................................. 307 Laboratory Tests: ........................................................................................................................................ 307 13REFERENCES ........................................................................................................................................... 309 ix LIST OF FIGURES Figure 1-1: Crash risk, Road Site Category and Standard of Skid Resistance - Idealised from (Rogers & Gargett, 1991) ............................................................................................................................................................................. 2 Figure 2-1: Road Asset Management components / process (N.K. Pradhan et al., 2001)........................................... 12 Figure 2-2: Flow Diagram of Linked Progressive Pavement and Surfacing Deterioration and Associated Maintenance Activities (modified from RIMS, 1999). ............................................................................................... 14 Figure 2-3: Interaction between driver-vehicle-roadway /environment (Lamm et al., 1999). .................................... 15 Figure 2-4: Factors Contributing to Road Crashes (adapted from Ogden and Taylor (1996) sourced from (Sabey, 1980) - UK and Treat (1980)-US)............................................................................................................................... 16 Figure 2-5: Three Level Model of the Driver Vehicle Roadway / Environment (modified from Lamm et al (1999)) ........................................................................................................................................................................ 17 Figure 2-6: Relative Risk of a Surface being a Crash site (sourced from Cairney, (1997))........................................ 19 Figure 2-7: Risk of accidents on wet roads and Mean Summer SCRIM Coefficient (MSSC) from Rogers and Gargett (1991).......................................................................................................................................................................... 19 Figure 2-8: Mean Crash (accident) Risk by Skid Resistance and Site Category (Viner et al., 2005) ......................... 22 Figure 2-9: Vehicle Movements (Lamm et al., 1999) ................................................................................................. 28 Figure 2-10: Mechanisms of adhesion and hysteresis (J. W. H. Oliver, 2003b) ......................................................... 30 Figure 2-11: Factors affecting the friction potential (Lamm et al., 1999)................................................................... 31 Figure 2-12: Horizontal forces between Road Surface and Motor Vehicle (Lamm et al., 1999)................................ 32 Figure 2-13: Relationship between longitudinal (tangential) and radial (side force) under varying conditions (Lamm et al., 1999) ................................................................................................................................................................. 32 Figure 2-14: Definition of the friction potential (Lamm et al., 1999) ......................................................................... 33 Figure 2-15: The Friction Curve (Lamm et al., 1999)................................................................................................. 35 Figure 2-16: Distribution of Skidding Values G (tangential friction factor, fT) with Speed V (Lamm et al., 1999) originally developed by Wehner (1965)...................................................................................................................... 35 Figure 3-1: Road surface wavelength spectrum, from Huschek, (1990), source Lay, (1998)..................................... 40 Figure 3-2: Illustration of Texture Ranges (Sandberg, 1999) ..................................................................................... 40 Figure 3-3: Microtexture and Macrotexture (Highways Agency, 2001)..................................................................... 41 Figure 3-4: Idealised positive and negative macrotextures (Walsh, 2000) ................................................................. 42 Figure 3-5: Relationship between microtexture, macrotexture, friction and speed (PIARC World Road Association, 2003) ........................................................................................................................................................................... 43 Figure 3-6: Scanning Electron Microscope photographs of an Aggregate in an Unpolished and Polished state (Austroads, 2005b)...................................................................................................................................................... 47 Figure 3-7: Increase in Skid Resistance due to a decrease in traffic on UK Trunk Road A4 (Smith & Collis, 2001) 47 Figure 3-8: Effect of traffic on skidding resistance of a typical motorway standard surfacing(Rogers & Gargett, 1991) ........................................................................................................................................................................... 51 Figure 3-9: Simplified general pavement polishing model (Prowell et al. 2003)........................................................ 52 Figure 3-10: Change in Skid Resistance with time for a section of 14mm SMA (W. D. H. Woodward et al., 2005) 52 Figure 3-11: Skid Resistance variation during a rainfall event (Bird and Scott, 1936)............................................... 54 Figure 3-12: Reductions in Coefficients of Friction due to wet surfaces -adapted from (PIARC World Road Association, 2003) ...................................................................................................................................................... 55 Figure 3-13: Model of a Wet Tyre Footprint (Jellie, 2003) ........................................................................................ 56 Figure 3-14: Variation in Skid resistance during a Rain event (Bennis & De Witt, 2003) ......................................... 58 Figure 3-15: Measured Coefficient of Friction (SCRIM) in the United Kingdom over 11 years (J.R. Hosking, 1976).................................................................................................................................................................................... 61 Figure 3-16: Long term skid resistance monitoring in Whangarei, NZ using British Pendulum Tester (P. D. Cenek et al., 1999) ..................................................................................................................................................................... 62 Figure 3-17: Estimate of the seasonal variation of SFC with the reported Mean Summer SCRIM Coefficient for the UK (Rogers and Gargett, 1991). ................................................................................................................................. 63 Figure 3-18: Seasonal Variation of skid Resistance in Western Australia, Victoria and Queensland (J.W.H. Oliver et al., 1988). .................................................................................................................................................................... 64 Figure 3-19: Influence of Rainfall on skid resistance - (Haydon, 2005) reproduced from (Hill & Henry, 1981)....... 65 Figure 3-20: Effects of pollutants and days since last rain on measured skid resistance (Hill & Henry, 1981).......... 66 Figure 4-1: Bias and Radial Tyre Construction (The Wheel and Tyre Bible, 2006)................................................... 71 Figure 4-2: Elements of tread design (Tyre Talk, 2006) ............................................................................................. 71 Figure 4-3: A Comparison of Tread Pattern Groove Volume (V ) Performance on two surfaces (Veith, 1983)....... 74 Figure 4-4: Wet Friction versus Durometer Hardness for several Tread Rubbers (Veith, 1983)................................ 74 Figure 4-5: Wet Traction rating versus Tg to R ratio(Veith, 1983) .......................................................................... 75 Figure 4-6: Wet Traction versus Speed for several Tread Rubbers(Veith, 1983) ..................................................... 76 Figure 4-7: Cross Section of tyre with low inflation pressure under heavy load (Lippman, 1985) ............................ 79 x Figure 4-8: Contact stresses imposed on the road surface within the tyre contact patch: (a) static tyre and (b) free rolling tyre (Lippman, 1985)....................................................................................................................................... 79 Figure 4-9: Classification of Skid Resistance Measuring contact Methods with common examples. ........................ 82 Figure 4-10: Relationship of Slip Speed to friction on a road surface (Austroads, 2005b)......................................... 82 Figure 4-11: Sideway Force Coefficient Method........................................................................................................ 84 Figure 4-12: WDM SCRIM Apparatus....................................................................................................................... 84 Figure 4-13: Early Skid Resistance measurement devices UK - 1930s to 1960s (P. G.Roe & Sinhal, 2005b)...... 85 Figure 4-14: SCRIM Wheel Assembly Unit (P. G.Roe & Sinhal, 2005a) ................................................................ 86 Figure 4-15: The GripTester (Findlay Irvine Ltd, 2005)............................................................................................. 87 Figure 4-16: SkidMan (Bullas, 2005) ......................................................................................................................... 88 Figure 4-17 Output from Electronic Recording Decelerometer (SkidMan) showing a comparison of ABS and non ABS braking (Bullas, 2005)........................................................................................................................................ 88 Figure 4-18: Road Analyser and Recorder - ROAR schematic (Pavement Management Services, 2005) ................. 89 Figure 4-19: ROAR device with testing wheel and hydraulic braking mechanism demonstrated. ............................. 89 Figure 4-20: Dynatest 1295 Pavement Friction Tester (Dynatest, 2005).................................................................... 90 Figure 4-21: Locked Wheel Trailer Testing mechanism (Dynatest, 2005) ................................................................. 90 Figure 4-22: Computer Screen Test Output from Dynatest 1295 Pavement Friction Tester (Dynatest, 2005)........... 91 Figure 4-23: British Pendulum Tester (Austroads, 2005b) ......................................................................................... 91 Figure 4-24: Schematic of British Pendulum Tester (BPT) set up for Laboratory Testing (A. Woodside & Woodward, 2002)........................................................................................................................................................ 91 Figure 4-25: Dynamic Friction Tester (DF Tester) Components (Nippo Sangyo Co Ltd., 2005) .............................. 94 Figure 4-26: Dynamic Friction Tester (DF Tester) rubber sliders .............................................................................. 94 Figure 4-27: Prepared test sample showing chips embedded in epoxy (Transit NZ & Roading NZ, 2005). .............. 96 Figure 4-28: Accelerated Polishing Machine. ............................................................................................................. 97 Figure 4-29: Schematic of the Accelerated Polishing Machine (Woodside and Woodward, 2002). .......................... 97 Figure 4-30: Plot of PSV and AAV for arenaceous rocks (A. Woodside & Woodward, 2002) ................................. 98 Figure 4-31: Definitions of microtextural parameters (Forster, 1989) ...................................................................... 100 Figure 4-32: Sand patch method for measuring texture depth (A. Woodside & Woodward, 2002) ......................... 102 Figure 4-33: Laser Sensors for Texture Measurements (Millard, 1993) ................................................................... 103 Figure 4-34: Definition of Mean Profile Depth......................................................................................................... 103 Figure 4-35: Underestimate of NZ Skid Resistance based on UK PSV Equation - sourced from (Haydon, 2005)106 Figure 4-36: Penn State Model for two surfaces with differing textures (J J Henry, 2000)...................................... 109 Figure 4-37: Rado Model plot with typical values (J J Henry, 2000) ....................................................................... 110 Figure 4-38: A comparison of skid resistance measurements corrected for short-term variations (Hill & Henry, 1981).................................................................................................................................................................................. 113 Figure 5-1: University of Auckland GripTester and 4WD Tow Vehicle. ................................................................. 122 Figure 5-2: GripTester Automatic Watering System and Water Storage Tank in back of testing vehicle................ 122 Figure 5-3: Auckland Field Test Location Sites (source NZMS 262 Map series) .................................................... 126 Figure 5-4: Northland Field Test Location Sites (source ARC GIS) ........................................................................ 127 Figure 5-5: Tamaki Campus (University of Auckland) Test site .............................................................................. 128 Figure 5-6: Ports of Auckland Rail Grid site (source Auckland City Council aerial photo maps) ........................... 129 Figure 5-7 : Kaiwaka Slag Site (State Highway One Northland, RP 220/9.27 220/9.87)................................... 130 Figure 5-8: Brynderwyn South Curve (State Highway One Northland RP 220/0.36 220/0.532) ....................... 131 Figure 5-9 : Hikurangi Site (State Highway One Northland RP 144/6.215 144/6.766)...................................... 132 Figure 5-10 : Kara Road Site (State Highway 14 Northland RP 0/8.442 to 0/9.099) ............................................ 133 Figure 5-11 : Snooks - Tatton Site (State Highway 14 Northland RP 0/13.91 to 15/0.647) .................................. 133 Figure 5-12: Pavement surface detritus sample collection method. .......................................................................... 135 Figure 5-13: The UoA DFTester on a Prepared Sample ........................................................................................... 137 Figure 5-14: Rubber Sliders and Rotating Disk of the UoA DFTester ..................................................................... 137 Figure 5-15: Preparation of the Laboratory Surface Samples ................................................................................... 139 Figure 5-16: Schematic Front Elevation of the Accelerated Polishing Machine ...................................................... 141 Figure 5-17: The Accelerated Polishing Machine (left) with DF Tester (right)........................................................ 141 Figure 5-18: The Accelerated Polishing Machine wheel assembly unit in operation ............................................... 141 Figure 5-19: Stages of Accelerated Polishing modified from Prowell et al. (2003) ................................................. 142 Figure 6-1: Flow Chart of the Process developed for Skid Resistance Field Tests................................................... 146 Figure 6-2: Screen shot of the raw Access database file structure for a GripTester Survey ..................................... 149 Figure 6-3: GripTester Raw Markers Access database Table ................................................................................... 149 Figure 6-4: GripTester Raw Data Access database Table......................................................................................... 149 Figure 6-5: GripTester Pre-Survey Screen................................................................................................................ 150 Figure 6-6: Example Plot of the Coefficient of Friction (GN) in relation to Distance (chainage) at Kaiwaka in Northland on SH 1 .................................................................................................................................................... 151 Figure 6-7: Example Statistical Plot of the GripTester survey data at Kaiwaka in Northland on SH 1.................... 152 Figure 6-8: Statistical Plot of the GripTester survey at Kaiwaka when the New Seal was 2.5 months old .............. 153 Figure 6-9: The Variation of GripTester runs at the Kaiwaka site over 26 month period......................................... 153 xi Figure 6-10: The Variation in Average GN, SFC and Macrotexture over Time at the Kaiwaka site over 26 month period ........................................................................................................................................................................ 154 Figure 6-11: Typical Processed Dynamic Friction Test Result showing three test runs........................................... 156 Figure 6-12: Tamaki Campus Summary results over time (Flat section, both directions) ........................................ 158 Figure 6-13: Tamaki Campus Summary results over time (Slope section, both directions) ..................................... 159 Figure 6-14: Ports of Auckland site Summary results over time (West direction).................................................... 162 Figure 6-15: Ports of Auckland site Summary results over time (East direction)..................................................... 163 Figure 6-16: Kaiwaka Slag Site Summary Results over Time (Both directions)...................................................... 165 Figure 6-17: Brynderwyn South Curve Site Summary results over time (Both directions) ...................................... 168 Figure 6-18: Hikurangi Control Site Summary results over time (Both directions) ................................................. 171 Figure 6-19: Kara Road Site Summary results over time (Both directions).............................................................. 173 Figure 6-20: Snooks Tatton Site Summary results over time (Both directions)..................................................... 175 Figure 6-21: Measured Skid resistance over Time in Comparison to Published PSV for Northland Sites............... 177 Figure 7-1: Multiple runs of the GripTester on the same day and same site. ............................................................ 181 Figure 7-2: Box-plot of GripNumber (GN) showing Mean, Minimum and Maximum GripTester values in comparison to the Age of the Seal, Kaiwaka (Increasing Direction) ........................................................................ 182 Figure 7-3: GripTester CoV between runs in relation to Age of Seal, Kaiwaka (Increasing Direction)................... 182 Figure 7-4: GripTester Coefficient of Variation between runs in relation to Number of Days since March of each year, Kaiwaka (Increasing Direction) ....................................................................................................................... 183 Figure 7-5: GripTester Coefficient of Variation between runs for all Northland sites.............................................. 183 Figure 7-6: A comparison of run to run variability of the GripTester and DF Tester devices .................................. 185 Figure 7-7: Tamaki Campus DFT 20 and CoV by calendar month of the year. ....................................................... 185 Figure 7-8: Ports of Auckland DFT 20 and CoV by calendar month of the year...................................................... 186 Figure 7-9: Normalised DFT20 results and CoV by Calendar month of the year for Auckland Sites. ..................... 187 Figure 7-10: Normalised GripTester results and recorded Surface Temperature on Asphalt Mix surfaces.............. 189 Figure 7-11: Normalised GripTester results and recorded Surface Temperature on Northland chip seal Sites........ 189 Figure 7-12: Normalised GripTester results and recorded Ambient Temperature on Asphalt Mix surfaces ............ 190 Figure 7-13: Normalised GripTester results and recorded Ambient Temperature on Northland chip seal Sites ...... 190 Figure 7-14: GripTester Coefficient of Variation and Surface Temperature of Northland sites. .............................. 191 Figure 7-15: Surface Temperature effects on the DF Tester device.......................................................................... 192 Figure 7-16: A comparison of the effects of Surface Temperature on the GripTester and DF Tester devices. ........ 193 Figure 7-17: The effects of Temperature and Change of Rubber Sliders on DF Tester Results............................... 194 Figure 7-18: Comparison of the GripTester and DF Tester results on an Asphalt Mix ............................................ 197 Figure 7-19: Correlation between the GripTester and DF Tester at 1m interval spacings ........................................ 197 Figure 7-20: Correlation between the GripTester and DF Tester for all sites ........................................................... 198 Figure 7-21: Example GripTester and SCRIM survey for the Snooks Tatton Northland site................................... 199 Figure 7-22: A Comparison of Correlation relationships for the SCRIM and GripTester ........................................ 201 Figure 7-23: International Friction Index (IFI) F60 and Sp for Kaiwaka Slag site against time ............................... 203 Figure 7-24: IFI F60 correlation between the GripTester and SCRIM devices ........................................................ 203 Figure 7-25: IFI F60 Correlation between the GripTester and Dynamic Friction Tester devices............................. 204 Figure 7-26: Schematic diagram of Christchurch Trial Test site (Austroads, 2005a)............................................... 205 Figure 7-27: GripTester results as compared with the Dynamic Friction Tester (Christchurch trials) ..................... 207 Figure 7-28: All devices compared with the Dynamic Friction Tester (Christchurch trials) .................................... 208 Figure 7-29: GripTester correlated against SCRIM on Christchurch test trial sites.................................................. 209 Figure 7-30: Dynamic Friction Tester and In-vehicle Decelerometers..................................................................... 210 Figure 7-31: Christchurch Trial surfaces Raw CoF and Transformed IFI F60 ......................................................... 211 Figure 7-32: Correlation of the DF Tester device with other devices using IFI F60 Transformations ..................... 212 Figure 7-33: IFI F60 Correlation Results of the Australian Friction Workshop Between the DF Tester, SCRIM, GripTester and ROAR - Dardano (2005).................................................................................................................. 213 Figure 8-1: Seasonal Variation of Auckland Asphalt Mix Surfaces over 3 Year Period .......................................... 216 Figure 8-2: The Normalised GripTester Results (NGN) for the Auckland Asphalt Mix Sites by Month of Year .... 217 Figure 8-3: Seasonal Variation of Northland Chipseal Surfaces over 2 year Period, (Increasing direction) ............ 219 Figure 8-4: Seasonal variation of Northland Chipseal Surfaces over 2 year period, (Decreasing direction) ............ 219 Figure 8-5: The Normalised GripTester Results (NGN) for the Northland Chipseal sites by Month of Year .......... 220 Figure 8-6: The Normalised GripTester Results (NGN) for the Northland Chipseal sites by Quarter of Year......... 221 Figure 8-7:Measured Decline in Skid Resistance due to Environmental Effects (P.D. Cenek & Davies, 2004)...... 223 Figure 8-8: Measured increase in skid resistance during rainfall event (Cenek et al., 2004).................................... 223 Figure 8-9: Days Since Last Rainfall and GripNumber (Hikurangi site) for Various Depths of Rainfall ................ 227 Figure 8-10: Dry Spell Factor (DSF) and GripNumber (Hikurangi site) for various depths of rainfall.................... 229 Figure 8-11: Weighted Rain Function (WRF) and GripNumber (Hikurangi site) for Various Rainfall Periods ...... 231 Figure 8-12: DSLR and DSF Analysis with the SCRIM device (Hikurangi site)..................................................... 232 Figure 8-13: Weighted Rain Function (WRF) and SCRIM SFC (Hikurangi site) for Various Rainfall Periods ...... 234 Figure 8-14: Days Since Last Rainfall (DSLR>5mm) and Normalised GripNumber (NGN) for Northland sites ... 235 Figure 8-15: Dry Spell Factor (DSF>5mm) and Normalised GripNumber (NGN) for Northland sites ................... 236 xii Figure 8-16: Weighted Rain Function (WRF07) and Normalised GripNumber (NGN) for Northland sites............ 236 Figure 8-17: Performance of the New Seal in Comparison to the Old Adjacent Seal (Kara Road).......................... 238 Figure 8-18: Performance of a Straight with Curved Geometrics (Kara Road) New Seal..................................... 239 Figure 8-19: Performance of a Level section in comparison with -6% Gradient (Kara Road) - New Seal............... 239 Figure 8-20: Results of Washing Trials on Hikurangi Site, Northland (Pre and Post Washing) .............................. 241 Figure 8-21: Before and After Results of the Washing Trials (decreasing direction) ............................................... 242 Figure 9-1: Mean Sediment Load at Each Site (mg/m2) ........................................................................................... 246 Figure 9-2: Mean Particle Size Distributions of Solid Samples................................................................................ 247 Figure 9-3: Distributions of road runoff sediment sizes from literature - Modified from Walker et al. (1999) and Ng et al. (2003) ............................................................................................................................................................... 248 Figure 9-4: Metal Concentration of Each Sample..................................................................................................... 248 Figure 9-5: Carbon Load in Sediments (mg/g) ......................................................................................................... 249 Figure 9-6: TOC Concentration of each sample (mg/L) ........................................................................................... 250 Figure 10-1: Moutohora Sandstone Chips ................................................................................................................ 253 Figure 10-2: Microphoto of Typical Otaika Greywacke Sandstone Thinsection(diameter field of view is 2mm) ... 254 Figure 10-3: Microphoto of Typical Holcim Basalt Thinsection (diameter field of view is 2mm) .......................... 255 Figure 10-4: Iron and Steel Making Aggregates in New Zealand (SteelServ Ltd & Bourke, 2005)......................... 255 Figure 10-5: Microphoto of Typical Melter Slag Thinsection (diameter field of view is 2mm)............................... 256 Figure 10-6: Stage 1 Polishing of Moutohora Greywacke Aggregate ...................................................................... 258 Figure 10-7: Moutohora Greywacke Sandstone Chips (Unpolished and Polished states) ........................................ 259 Figure 10-8: Stage 1 Polishing of Holcim Basalt Aggregate .................................................................................... 260 Figure 10-9: Holcim Basalt Chips (Unpolished and Polished States)....................................................................... 260 Figure 10-10: Stage 1 Polishing of Otaika Greywacke............................................................................................. 261 Figure 10-11: Otaika Greywacke Sandstone Chips (Unpolished and Polished states) ............................................. 262 Figure 10-12: Stage 1 Polishing of Melter Slag Aggregate ...................................................................................... 263 Figure 10-13: Melter Slag Chips (Unpolished and Polished States) ......................................................................... 263 Figure 10-14: Summary of Accelerated Polishing of all Laboratory Samples to ESR (Stage 1) .............................. 265 Figure 10-15: Moutohora Greywacke Laboratory Sample (Stages 1 and 2 Polishing Phases) ................................. 270 Figure 10-16: Moutohora Greywacke Laboratory Samples (Stage 2 Polishing with Addition of Contaminants) .... 271 Figure 10-17: Holcim Basalt Laboratory Sample (Stages 1 and 2 Polishing Phases) ............................................... 272 Figure 10-18: Holcim Basalt Laboratory Samples (Stage 2 Polishing with Addition of Contaminants) .................. 274 Figure 10-19: Otaika Greywacke Laboratory Sample (Stages 1 and 2 Polishing Phases) ........................................ 275 Figure 10-20: Otaika Greywacke Laboratory Samples (Stage 2 Polishing with Addition of Contaminants) ........... 276 Figure 10-21: Melter Slag Laboratory Sample (Stages 1 and 2 Polishing Phases) ................................................... 277 Figure 10-22: Melter Slag Laboratory Samples (Stage 2 Polishing with Addition of Contaminants) ...................... 278 Figure 10-23: Skid Resistance DFT () and the Effects of the Addition of Contaminants on the 4 Lab Samples ... 280 Figure 10-24: Skid Resistance DFT () and the Effects of the Addition of Contaminants and the % Difference from the Initial SR value for the 4 Lab samples ................................................................................................................ 282 Figure 10-25: Moutohora - After Polishing with Various Contaminants (approx. field of view 3.5x 2mm)............ 283 Figure 10-26: Holcim basalt - After Polishing with Various Contaminants (approx. field of view 3.5x 2mm)) ...... 283 Figure 10-27: Otaika Greywacke - After Polishing with Various Contaminants (approx. field of view 3.5x 2mm)).................................................................................................................................................................................. 284 Figure 10-28: Melter Slag - After Polishing with various contaminants (approx. field of view 3.5x 2mm)) ........... 285 xiii LIST OF TABLES Table 2-1: Pavement Surfacing Parameters requiring Performance Monitoring (Austroads 2003).............................. 8 Table 2-2: Development Streams of Predictive Modelling - modified from (Pradhan et al. 2001) ............................ 11 Table 2-3: Diagrammatic Representation of Investigatory Levels in HD 28/04 (Haydon 2005)................................ 26 Table 2-4: Investigatory Levels (IL) for identifying sites requiring inspection (Transit New Zealand 2002a) .......... 27 Table 3-1: Factors affecting the skid properties of a road........................................................................................... 39 Table 3-2: Geological properties of aggregate origins related to resistance to abrasion............................................. 46 Table 3-3: Geological Properties of Aggregate Origins Related to Resistance to Polishing....................................... 48 Table 4-1: Functions of Tyre tread elements (Tyre Talk, 2006) ................................................................................. 72 Table 5-1: Field Testing Sites - Location and General details .................................................................................. 120 Table 5-2: Field Testing Sites - Surface Material characteristics, properties and Loads .......................................... 120 Table 6-1: Tamaki Campus Site Descriptive Statistics (Flat Section) ...................................................................... 159 Table 6-2: Tamaki Campus Site Descriptive Statistics (Slope Section) ................................................................... 160 Table 6-3: Ports of Auckland field site Summary Statistics (both directions) .......................................................... 163 Table 6-4: Kaiwaka Slag site Summary Statistics (both directions) ......................................................................... 166 Table 6-5: Brynderwyn South curve site Summary Statistics (both directions)........................................................ 168 Table 6-6: Hikurangi site Summary Statistics (both directions) ............................................................................... 171 Table 6-7: Kara Road site Summary Statistics (both directions) .............................................................................. 174 Table 6-8: Snooks - Tatton Road site Summary Statistics (both directions)............................................................. 176 Table 6-9: Summary Coefficient of Friction Statistics of the Field Sites.................................................................. 178 Table 7-1: PIARC IFI Transformation Coefficients (Wambold et al., 1995) ........................................................... 202 Table 7-2: Coefficient of Determination (R2) between surface friction devices from Christchurch trials ................ 209 Table 8-1: Normalised GripTester results for Auckland Sites by Calendar Month of Year ..................................... 218 Table 8-2: Normalised GripTester results for Northland Sites by Calendar Month of the Year............................... 221 Table 8-3: Correlation of NIWA Rainfall Gauges with Manually Recorded Data ................................................... 224 Table 9-1: Detritus Sampling Details (2005) ............................................................................................................ 244 Table 9-2: Preliminary Study Detritus Sampling Details (2004) .............................................................................. 245 Table 9-3: Preceding 15-day Rainfall Depth (mm)................................................................................................... 245 Table 9-4: Mean Particle Size Distribution Data of Each Site.................................................................................. 247 Table 10-1: Laboratory Test Sample Details ............................................................................................................ 257 Table 10-2: Stage 1 Wet Polishing Results until 'Equilibrium Level' is reached ...................................................... 257 Table 10-3: Major Mineral Constituents of the Aggregates used in the Laboratory Experiments (Black, 2005b) ... 267 Table 10-4: DFT() and % Difference in Results of the Stage 2 Addition of Contaminants and Accelerated Polishing.................................................................................................................................................................................. 279 xiv ABBREVIATIONS AND ACRONYMS 95% Conf95% Confidence value AADTAnnual Average Daily Traffic Volume AAVAggregate Abrasion Value ABS Anti-lock Braking System ACAsphaltic Concrete AC14 Asphalt Concrete 14mm maximum particle sizeADTAverage Daily Traffic AGD Average Greatest Dimension of the sealing chip (mm) AIVAggregate Impact Value ALD Average Least Dimension of the sealing chip (mm) APAccelerated Polishing APMAccelerated Polishing Machine ARRBARRB Group Limited (formerly ARRB Transport Research, Melbourne, Australia) ASTM American Society for Testing & Materials AVEAverage BC/BCRBenefit / Cost ratio BFCBraking Force Coefficient BPNBritish Pendulum Number BSBritish Standard BPT / PBPTPortable British Pendulum Tester CENCommittee for European

AN ANALYSIS OF THE SEASONAL AND SHORT-TERM VARIATION OF PAVEMENT SKID RESISTANCE.pdf

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