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 continues to be difficult due to the inherent and sometimes random variation in skid resistance levels over time. This study is an investigation and analysis of seasonal and short term variation of measured skid resistance in two phases. Phase 1: Regular field monitoring was undertaken using the GripTester and the Dynamic Friction Tester measurement devices on seven sites in the Auckland and Northland Regions of New Zealand was undertaken over a three year period. The effects of temperature, rainfall, contaminants, new surfacings, geometric elements and aggregate properties were analysed to investigate factors that initiate changes in the measured skid resistance of pavement surfacings. Phase 2: Laboratory prepared samples were constructed for accelerated polishing and skid resistance testing of four different aggregates (two greywackes, a basalt and an artificial iron-making melter slag aggregate). The samples were polished in an accelerated polishing machine to an ‘equilibrium skid resistance’ level (Stage 1 polishing). Contaminants were then added to the accelerated polishing process to determine the effect of varying additive, particle size and hardness in an attempt to simulate seasonal and/or short-term variations that occur in the field. The results have demonstrated that significant and previously unpredictable variations (greater than 30%) 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 contaminants themselves, the previous rainfall history, the road geometry, the calendar month of the year and (depending upon the measurement device), the temperature during testing. The laboratory tests demonstrate that accelerated polishing tests of aggregate samples could be prepared for testing by the Dynamic Friction Tester and 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 differences which were related to the geological properties of the aggregates themselves, as well as the contaminants used in the accelerated polishing process. The findings of the research have specific relevance to three areas of industry; Road Controlling Authorities who are primarily interested in skid resistance policy, standards and management, Road Asset Managers who operate, maintain and manage condition level and the safety aspects of the road network and Crash Investigators who collect and analyse crash data primarily for legal proceedings. All three of these industry organisations need to clearly understand the inherent variability of skid resistance, the factors involved and the effects that geological and environmental variations have on skid resistance measurement. / Specific appreciation (as outlined below) is given to the significant industry partners/supporters that have helped support the research in many different ways. Firstly, I must give special thanks to Works Infrastructure Limited who have supported the research both financially and with resources almost from the outset of the research programme. The field testing data collection in the Northland Region of New Zealand would not have been possible without the support of the Whangarei Works Infrastructure team which included Peter Houba, Peter King, Matthew Findlay, Glen Kirk and the temporary traffic control team headed by Derek Phillips. Thanks also go to the Auckland Works Infrastructure testing laboratory which supplied aggregate supplies for laboratory sampling and testing and whose technicians also undertook Polished Stone Value tests on the aggregate samples. Special thanks are also given to Michael Haydon and David Hutchison from the technical management team of Works Infrastructure who have always been willing to listen to my requests and the many discussions that we have had on aspects of skid resistance, policy and technical matters. Pavement Management Services and especially Dr John Yeaman and Daniel Rich for their support for the research programme from the beginning, and secondly for financially contributing to the purchase of the Dynamic Friction Tester for the static field testing and the laboratory tests. Achnowledgement is also given to The Ports of Auckland and especially Jo Campbell of the AXIS Intermodal group that allowed access to the rail grid site as a field-testing site outside of normal port operation hours. Transit New Zealand head office staff (Mark Owen, David Cook and Chris Parkman) are also thanked for their support of the research and in enabling access to historic SCRIM and RAMM data on the Transit New Zealand state Highway network. Land Transport New Zealand (formerly Transfund New Zealand) are acknowledged for their significant financial support of the research, in terms of the Land Transport New Zealand Research project that allowed the field research data collection and analysis programme to continue for a further year and for the extension to the controlled laboratory testing.

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 continues to be difficult due to the inherent and sometimes random variation in skid resistance levels over time. This study is an investigation and analysis of seasonal and short term variation of measured skid resistance in two phases. Phase 1: Regular field monitoring was undertaken using the GripTester and the Dynamic Friction Tester measurement devices on seven sites in the Auckland and Northland Regions of New Zealand was undertaken over a three year period. The effects of temperature, rainfall, contaminants, new surfacings, geometric elements and aggregate properties were analysed to investigate factors that initiate changes in the measured skid resistance of pavement surfacings. Phase 2: Laboratory prepared samples were constructed for accelerated polishing and skid resistance testing of four different aggregates (two greywackes, a basalt and an artificial iron-making melter slag aggregate). The samples were polished in an accelerated polishing machine to an ‘equilibrium skid resistance’ level (Stage 1 polishing). Contaminants were then added to the accelerated polishing process to determine the effect of varying additive, particle size and hardness in an attempt to simulate seasonal and/or short-term variations that occur in the field. The results have demonstrated that significant and previously unpredictable variations (greater than 30%) 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 contaminants themselves, the previous rainfall history, the road geometry, the calendar month of the year and (depending upon the measurement device), the temperature during testing. The laboratory tests demonstrate that accelerated polishing tests of aggregate samples could be prepared for testing by the Dynamic Friction Tester and 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 differences which were related to the geological properties of the aggregates themselves, as well as the contaminants used in the accelerated polishing process. The findings of the research have specific relevance to three areas of industry; Road Controlling Authorities who are primarily interested in skid resistance policy, standards and management, Road Asset Managers who operate, maintain and manage condition level and the safety aspects of the road network and Crash Investigators who collect and analyse crash data primarily for legal proceedings. All three of these industry organisations need to clearly understand the inherent variability of skid resistance, the factors involved and the effects that geological and environmental variations have on skid resistance measurement. / Specific appreciation (as outlined below) is given to the significant industry partners/supporters that have helped support the research in many different ways. Firstly, I must give special thanks to Works Infrastructure Limited who have supported the research both financially and with resources almost from the outset of the research programme. The field testing data collection in the Northland Region of New Zealand would not have been possible without the support of the Whangarei Works Infrastructure team which included Peter Houba, Peter King, Matthew Findlay, Glen Kirk and the temporary traffic control team headed by Derek Phillips. Thanks also go to the Auckland Works Infrastructure testing laboratory which supplied aggregate supplies for laboratory sampling and testing and whose technicians also undertook Polished Stone Value tests on the aggregate samples. Special thanks are also given to Michael Haydon and David Hutchison from the technical management team of Works Infrastructure who have always been willing to listen to my requests and the many discussions that we have had on aspects of skid resistance, policy and technical matters. Pavement Management Services and especially Dr John Yeaman and Daniel Rich for their support for the research programme from the beginning, and secondly for financially contributing to the purchase of the Dynamic Friction Tester for the static field testing and the laboratory tests. Achnowledgement is also given to The Ports of Auckland and especially Jo Campbell of the AXIS Intermodal group that allowed access to the rail grid site as a field-testing site outside of normal port operation hours. Transit New Zealand head office staff (Mark Owen, David Cook and Chris Parkman) are also thanked for their support of the research and in enabling access to historic SCRIM and RAMM data on the Transit New Zealand state Highway network. Land Transport New Zealand (formerly Transfund New Zealand) are acknowledged for their significant financial support of the research, in terms of the Land Transport New Zealand Research project that allowed the field research data collection and analysis programme to continue for a further year and for the extension to the controlled laboratory testing.

Rail corrugation is a periodic wear pattern that develops on the wheel and rail contacting surfaces in railway systems. It is a commonly observed phenomenon worldwide and is a serious problem because it causes degradation of the track and its components and is a significant source of noise. Currently the only reliable method of ameliorating the negative effects of rail corrugation is to periodically regrind the rail surface to a smooth profile, at great expense to the railway operator. It is therefore of interest to investigate other possible control strategies to reduce corrugation growth through an understanding of the mechanism of corrugation formation. This thesis presents an investigation into the effect of speed variation on the corrugation formation mechanism. The research presented is intended to highlight the significant role that speed variation has on corrugation formation via a disruption of the feedback mechanism which leads to corrugation growth over successive train passages. This discovery motivates the investigation the feasibility of altered speed variation as a novel corrugation control method, due to the large effect that the variance of train speed has on corrugation growth rates. The effect of variable pass speed on corrugation formation has been investigated in this thesis through the use of efficient models of corrugation formation in straight track and cornering conditions. These models are simple enough to readily perform corrugation control studies without neglecting any relevant physics, obscuring the corrugation formation mechanism with overly detailed modelling or imposing a significant computational burden on performing control studies. These novel models have been outlined and their predictions elucidated in detail. A theoretical investigation into the effect of speed variation in the presence of a resonance free mechanism for corrugation growth via a contact filter has been performed and shown to only be important when the dynamic wavelength of formation approaches the size of the contact patch. The results of these corrugation models have been validated via test rig and field experiments. An investigation of the effectiveness of speed variation as a corrugation growth control measure has also been investigated via test rig experiments. The results of this thesis have formed the basis of an industry supported field trail of this technique for corrugation mitigation that is currently in progress.

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 continues to be difficult due to the inherent and sometimes random variation in skid resistance levels over time. This study is an investigation and analysis of seasonal and short term variation of measured skid resistance in two phases. Phase 1: Regular field monitoring was undertaken using the GripTester and the Dynamic Friction Tester measurement devices on seven sites in the Auckland and Northland Regions of New Zealand was undertaken over a three year period. The effects of temperature, rainfall, contaminants, new surfacings, geometric elements and aggregate properties were analysed to investigate factors that initiate changes in the measured skid resistance of pavement surfacings. Phase 2: Laboratory prepared samples were constructed for accelerated polishing and skid resistance testing of four different aggregates (two greywackes, a basalt and an artificial iron-making melter slag aggregate). The samples were polished in an accelerated polishing machine to an ‘equilibrium skid resistance’ level (Stage 1 polishing). Contaminants were then added to the accelerated polishing process to determine the effect of varying additive, particle size and hardness in an attempt to simulate seasonal and/or short-term variations that occur in the field. The results have demonstrated that significant and previously unpredictable variations (greater than 30%) 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 contaminants themselves, the previous rainfall history, the road geometry, the calendar month of the year and (depending upon the measurement device), the temperature during testing. The laboratory tests demonstrate that accelerated polishing tests of aggregate samples could be prepared for testing by the Dynamic Friction Tester and 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 differences which were related to the geological properties of the aggregates themselves, as well as the contaminants used in the accelerated polishing process. The findings of the research have specific relevance to three areas of industry; Road Controlling Authorities who are primarily interested in skid resistance policy, standards and management, Road Asset Managers who operate, maintain and manage condition level and the safety aspects of the road network and Crash Investigators who collect and analyse crash data primarily for legal proceedings. All three of these industry organisations need to clearly understand the inherent variability of skid resistance, the factors involved and the effects that geological and environmental variations have on skid resistance measurement. / Specific appreciation (as outlined below) is given to the significant industry partners/supporters that have helped support the research in many different ways. Firstly, I must give special thanks to Works Infrastructure Limited who have supported the research both financially and with resources almost from the outset of the research programme. The field testing data collection in the Northland Region of New Zealand would not have been possible without the support of the Whangarei Works Infrastructure team which included Peter Houba, Peter King, Matthew Findlay, Glen Kirk and the temporary traffic control team headed by Derek Phillips. Thanks also go to the Auckland Works Infrastructure testing laboratory which supplied aggregate supplies for laboratory sampling and testing and whose technicians also undertook Polished Stone Value tests on the aggregate samples. Special thanks are also given to Michael Haydon and David Hutchison from the technical management team of Works Infrastructure who have always been willing to listen to my requests and the many discussions that we have had on aspects of skid resistance, policy and technical matters. Pavement Management Services and especially Dr John Yeaman and Daniel Rich for their support for the research programme from the beginning, and secondly for financially contributing to the purchase of the Dynamic Friction Tester for the static field testing and the laboratory tests. Achnowledgement is also given to The Ports of Auckland and especially Jo Campbell of the AXIS Intermodal group that allowed access to the rail grid site as a field-testing site outside of normal port operation hours. Transit New Zealand head office staff (Mark Owen, David Cook and Chris Parkman) are also thanked for their support of the research and in enabling access to historic SCRIM and RAMM data on the Transit New Zealand state Highway network. Land Transport New Zealand (formerly Transfund New Zealand) are acknowledged for their significant financial support of the research, in terms of the Land Transport New Zealand Research project that allowed the field research data collection and analysis programme to continue for a further year and for the extension to the controlled laboratory testing.

Doctor of Philosophy (PhD) / This thesis aims to establish a sound scientific methodology for the effective and efficient polishing of thermally stable PCD composites (consisting of diamond and SiC) for cutting tools applications. The surface roughness of industrial PCD cutting tools, 0.06 μm Ra is currently achieved by mechanical polishing which is time consuming and costly because it takes about three hours to polish a 12.7 mm diameter PCD surface. An alternative technique, dynamic friction polishing (DFP) which utilizes the thermo-chemical reactions between the PCD surfaces and a catalytic metal disk rotating at high peripheral speed has been comprehensively investigated for highly efficient abrasive-free polishing of PCD composites. A special polishing machine was designed and manufactured in-house to carry out the DFP of PCD composites efficiently and in a controllable manner according to the requirements of DFP. The PCD polishing process and material removal mechanism were comprehensively investigated by using a combination of the various characterization techniques: optical microscopy, SEM and EDX, AFM, XRD, Raman spectroscopy, TEM, STEM and EELS, etc. A theoretical model was developed to predict temperature rise at the interface of the polishing disk and PCD asperities. On-line temperature measurements were carried out to determine subsurface temperatures for a range of polishing conditions. A method was also developed to extrapolate these measured temperatures to the PCD surface, which were compared with the theoretical results. The material removal mechanism was further explored by theoretical study of the interface reactions under these polishing conditions, with particular emphasis on temperature, contact with catalytic metals and polishing environment. Based on the experimental results and theoretical analyses, the material removal mechanism of dynamic friction polishing can be described as follows: conversion of diamond into non-diamond carbon takes place due to the frictional heating and the interaction of diamond with catalyst metal disk; then a part of the transformed material is detached from the PCD surface as it is weakly bonded; another part of the non-diamond carbon oxidizes and escapes as CO or CO2 gas and the rest diffuses into the metal disk. Meanwhile, another component of PCD, SiC also chemically reacted and transformed to amorphous silicon oxide/carbide, which is then mechanically or chemically removed. Finally an attempt was made to optimise the polishing process by investigating the effect of polishing parameters on material removal rate, surface characteristics and cracking /fracture of PCD to achieve the surface roughness requirement. It was found that combining dynamic friction polishing and mechanical abrasive polishing, a very high polishing rate and good quality surface could be obtained. The final surface roughness could be reduced to 50 nm Ra for two types of PCD specimens considered from pre-polishing value of 0.7 or 1.5 μm Ra. The polishing time required was 18 minutes, a ten fold reduction compared with the mechanical abrasive polishing currently used in industry.

Thesis (M.S.)--University of Texas at El Paso, 2007. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

Thesis (M.S.)--Missouri University of Science and Technology, 2009. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed April 9, 2009) Includes bibliographical references (p. 118-127).

Thesis (M.S.)--University of Missouri--Rolla, 2007. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed June 17, 2008) Includes bibliographical references.

Thesis (Ph. D.)--Ohio State University, 2008. / Title from first page of PDF file. Includes bibliographical references (p. 181-192).

Thesis (M.S.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains x, 80 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 69-70).