This study focused on the correlation between the primary and the secondary impacts of a road development. Its methodology is aimed at coupling the conventional cost benefit analysis with an economic impact analysis. The secondary impacts of road development concentrated on the changes in land values. These changes were modelled using a new model; which related the percentage change in land values with four variables: the distance from the road; the land use; the land area; and the time that has elapsed since the completion of the roadworks. For a period of 30 years, a comparison was carried out to examine the similarities in the trends of the road users' benefits and the CLVs. Three main periods were found through this comparison. The first period is from year 0 to year 3; the second period is from year 4 after the road's opening to year 19; the last period starts from year 20 and finishes at the end of the analysis. The primary and secondary impacts in the first and the third periods of analysis behaved inversely; while the rest of the analysis period showed similar behaviour for the CLV and the RUCS. It was found that the factors affecting the degree of their similarity were traffic volume and the response of the network users to the new road. In addition, the limitation of the developed model of CLVs in terms of the variables used and particularly in their maximum and minimum values also affects the degree of similarity.

Millions are spent by authorities to maintain and repair the world's potholes. In addition to the direct costs, they can also lead to damaged vehicles and an accelerated deterioration of the road system. The potholes create traffic risks that lead to the daily loss of hundreds of work hours for drivers and passengers. Many road crews are not familiar with the proper materials and methods for pothole repair. Correct selection of pothole patching materials and proper application of repair procedures can greatly increase the longevity of pothole repairs, lead to fewer driver frustrations, and lower road maintenance budgets. The present study aims to develop innovative materials to repair of potholes by using induction heating technology. Three innovative patching materials to repair potholes are proposed, assessed and compared with conventional pothole patching materials. The first material is a combination of a prefabricated asphalt tile and a bonding layer that can be placed into a sanitised pothole and bonded by applying electromagnetic induction heating. The second material involves using prefabricated asphalt pellets to directly fill a pothole and then heated by induction. The third material comprises (1) prefabrication of binder pellets containing bitumen and steel wool that has been coated with a shell to avoid them sticking to each other; (2) the development of a mobile induction heating mixer that can mix the binder pellets with cold aggregate on-site before directly filling a pothole and compacting the mixture. In this research, their tensile and shear strength properties were assessed and demonstrated by repairing simulated potholes on testing slabs and subjected them to wheel tracking tests. The innovative patching materials showed excellent durability higher than a road repaired with cold mix asphalt. Furthermore, the innovative patching materials have been evaluated from economic and environmental standpoints and compared results with conventional hot mix and cold mix. These proposed patching materials have been applied by different raw materials and procedures, and have importance of properties that performed by laboratory tests. Based on the results of loaded wheel test, the service life of each patching materials has been calculated. An inventory was prepared to help quantify the energy requirements, material inputs, and emissions produced during production of raw materials, prefabrication of each product and their final installation. The requisite data was obtained from various sources in the literature. Two maintenance hypothesis were considered. The results showed that three innovative patching materials may be more sustainable and could reduce cost, energy usage and CO2 emissions over time in agreement with hypothesis 1. However, they may cause to increase the economic and environmental impacts over time in agreement with hypothesis 2.

Skid resistance is considered as one of the contributing factors that affect traffic accidents; it is considered as an important property of a road surface that is required to maintain a safe road network. The main aim of this thesis is to establish new skid resistance thresholds for local authority roads. This will be accomplished through the following objectives: 1. to define new site categories based on accident layouts at different network features (e.g. junctions, roundabouts) and the relationships between accidents and geometric characteristics (such as radius of curvature and gradient), 2. to estimate the impact of traffic characteristics (natural logarithm of annual average daily flow, percentage of heavy vehicles, and speed limit); geometric characteristics (radius of curvature, gradient, number of lanes and number of minor accesses); and pavement characteristics (skid resistance, rut depth, and texture depth) on both accident frequency and rate, and 3. To analyse the relation of the expected accident frequencies and rates as a function of skid resistance. This study has included A-road networks for Norfolk, Oxfordshire and Nottinghamshire counties in England, UK. These networks are divided into different site categories these site categories are: 1. non-event; 2. bends (0 - 250) m; 3. bends (250 - 500) m; 4. roundabouts; 5. junctions; 6. gradients. Four different datasets for the period 2005-2010 have been merged to construct the final unique dataset for this study. They are: 1. accident data, 2. traffic data; 3. geometric data; and 4. pavement characteristics data. A series of fixed and random parameters Negative Binomial models have been employed to investigate the effect of skid resistance on accident frequency at different site categories for the three counties. The datasets were modelled by total accidents, by road surface condition (i.e. dry and wet), and by severity level (i.e. fatal and serious or slight). In the same way fixed and random Tobit models have been employed to investigate the effect of skid resistance on accident rate. The model estimation results suggest that skid resistance is negatively associated with the frequency and rate for all accident types at all site categories. A 10% increase in skid resistance leads to a decrease in total, dry, wet, slight, and serious and fatal accident frequencies at network level by 12.24, 10.21, 16.34, 10.68 and 4.92%, respectively. A 10% increase in skid resistance (SCRIM value) leads to a decrease in total, dry, wet, slight, and serious and fatal accident rates at network level by 6.32%, 10.62%, 12.52%, 3.31%, and 4.87%, respectively. This thesis contributes to knowledge in terms of accident prediction approach, showing that application of random parameters modelling as a new approach applied in the UK to estimate accident frequency and rate on A - road networks. This method is introduced as a sufficient approach for the researcher due to the ability to account and correct for heterogeneity, which can arise as a result of several factors relating to the characteristics of traffic, geometric and pavement characteristics. In addition, the random parameters model approach provides a reasonable understanding of the main factors that affect accident frequency and rate. Therefore, this approach allows the researcher to identify and control for confounding factors that may bias estimation. In addition, new skid resistance thresholds for different site categories are established based on the analysis of expected accident frequencies (outputs of random parameters Negative Binomial models); and the analysis of expected accident rates (outputs of random parameters Tobit models) as function of skid resistance.

Age hardening of bitumen is one of the key factors determining the lifetime of an asphalt pavement. When the bitumen is excessively aged, the asphalt mixture will become brittle and its ability of supporting traffic-induced stresses and strains may significantly reduce, which can easily cause some cracking damage to the bound layer of a pavement. As bitumen is always in contact with mineral fillers in asphalt mixtures, the mechanisms of oxidative ageing of binders are significantly influenced by the physical and chemical interaction between fillers and the bitumen. For a long while, attempts to solve the ageing problem of asphalt binder by various methods, including polymer modification, nano-particle enhancement or functional improvement have been undertaken. Hydrated lime is one of many potential additives used in bitumen to improve the performance of asphalt mixtures. Hydrated lime in hot mix asphalt creates multiple benefits. A considerable amount of information exists in the literature on hydrated lime’s ability to control water sensitivity and its well-accepted ability as an anti-stripping agent to inhibit moisture damage. However, recent studies have shown that lime acts as an active filler and anti-oxidant. These properties create multiple benefits for pavements. Although the majority of research on the use of hydrated lime in asphalt mixtures has been carried out in the USA, the beneficial effects of hydrated lime have also been reported worldwide especially in Europe. In the UK, the use of hydrated lime only started in the early 2000’s and still needs a lot of research into its effect on the traditionally used asphalt materials in the UK pavement industry. This research primarily focuses on an in-depth investigation of bitumen ageing mechanisms and evaluation. Furthermore, this research aims to investigate the advantages of using hydrated lime to mitigate ageing in bitumen mastics and asphalts mixtures as a whole. The full project has been broken down into three parts. The first is a pure bitumen study, the second is a mastic level ageing study and the third is a mixture level ageing investigation. The bitumen ageing study investigated the effect of different ageing methods and parameters on bitumen ageing. In addition, this study focused on the mechanisms and factors affecting bitumen ageing and attempted to develop a better understanding of ageing evaluation methods with different perspectives; basic properties, mechanical and rheological behaviour using a dynamic shear rheometer (DSR) and finally a chemical approach with Fourier transform infrared (FTIR). The second level is the mastics level, which investigated the effect of different fillers on bitumen-filler mastic ageing. Particular attention was paid to study the benefits of using hydrated lime on ageing mitigating in the mastic phase. Furthermore, a detailed study at the mastic level was conducted to investigate the effect of hydrated lime on stiffening and ageing mitigation of bitumen mastics. Different means to evaluate this effect were implemented involving both physical and chemical properties. The evaluation testing was aimed at developing a better understanding of hydrated lime anti-oxidant effects on ageing mitigation. Moreover, special attention was paid to the interactions between hydrated lime and bitumen which affects the ageing of bitumen mastics. The third level was the mixture ageing level. In this study, the effect of hydrated lime replacement of the natural aggregate fillers was investigated. This effect on the asphalt mixtures was investigated by different tests on their mechanical properties such as indirect tensile stiffness modulus (ITSM), indirect tensile strength (ITS) and their fracture properties using the semi-circular bending (SCB) test. Furthermore, the effect of ageing on the recovered bitumen was evaluated. The results and conclusions from the performed studies indicate that hydrated lime slows down bitumen ageing more than granite and limestone fillers. This effect depends mainly on the bitumen type and filler concentration. In addition, the research showed that hydrated lime interacts differently with the different bitumens used in this study. This interaction affects stiffening and ageing properties of mastics and mixtures. Furthermore, results show that different ageing indices used in this project correlated well with each other and also with chemical changes. The detailed results from the FTIR tests on recovered fillers and bitumen from the mastics, showed the ability of hydrated lime to adsorb some of the bitumen components such as carboxylic acid products. This mechanism reduces the formation of ageing products and consequently reduces the age hardening of mastics and asphalt mixtures. Unlike hydrated lime, granite filler does not exhibit this ability to react with bitumen.

Gravel aggregates had been used extensively in the Houston District of Texas Department of Transportation (TxDOT) for continuously reinforced concrete pavements construction for many years. However, some of these pavements have been subject to early age delamination and eventual spalling damage. Therefore, a series of studies funded by TxDOT since the early 1990's has been conducted to gain a better understanding of mechanisms, material properties, and construction practices, and to provide guidelines and recommendations for minimizing early-age delamination in concrete pavements made with gravel aggregates. In this study, a test protocol to measure the bond strength between aggregates and cement mortar was established, and the effects of different material and construction parameters on the bond strength of concrete at early ages using a fractional factorial design were investigated. The significances of each factor to achieve better bonding performance were determined, and the optimum design combination was subsequently chosen and validated. Geometric parameters were proposed to characterize aggregate shape properties relative to bonding performance with the facilitation of the Aggregate Imaging System. A rating system based on utility theory was developed to evaluate the overall contribution of aggregate properties (i.e. physical, geometric, and chemical) to the concrete bonding capability and the feasibility of certain mixture design combinations. As for theoretical representation of the bond strength across the interfacial transition zone, a model of interfacial fracture energy between aggregate and mortar that represents the energy necessary to create a crack along the interface was formulated. This model built the connection between concrete properties at the meso-level (represented by the interfacial fracture energy between aggregate and mortar) and the macro-level (represented by fracture toughness of concrete and significant influencing materials and construction factors). In addition, the moisture effects on stress development of concrete pavements at early ages using field data as inputs were numerically simulated, and a fracture mechanics-based approach was used to predict the occurrence of delamination. A delamination detection protocol for the field was developed to explore the feasibility and potential of utilizing Ground Penetration Radar technology in delamination detection. Research findings from laboratory investigation, field testing, theoretical modeling, and numerical analysis were further validated through field test sections, and the associated framework for delamination guidelines was established.

A performance model and a reliability-based optimization model for flexible pavements that accounts for the effects of rehabilitation actions are developed. The developed performance model can be effectively implemented in all the applications that require the reliability (performance) of pavements, before and after the rehabilitation actions. The response surface methodology in conjunction with Monte Carlo simulation is used to evaluate pavement fragilities. To provide more flexibility, the parametric regression model that expresses fragilities in terms of decision variables is developed. Developed fragilities are used as performance measures in a reliability-based optimization model. Three decision policies for rehabilitation actions are formulated and evaluated using a genetic algorithm. The multi-objective genetic algorithm is used for obtaining optimal trade-off between performance and cost. To illustrate the developed model, a numerical study is presented. The developed performance model describes well the behavior of flexible pavement before as well as after rehabilitation actions. The sensitivity measures suggest that the reliability of flexible pavements before and after rehabilitation actions can effectively be improved by providing an asphalt layer as thick as possible in the initial design and improving the subgrade stiffness. The importance measures suggest that the asphalt layer modulus at the time of rehabilitation actions represent the principal uncertainty for the performance after rehabilitation actions. Statistical validation of the developed response model shows that the response surface methodology can be efficiently used to describe pavement responses. The results for parametric regression model indicate that the developed regression models are able to express the fragilities in terms of decision variables. Numerical illustration for optimization shows that the cost minimization and reliability maximization formulations can be efficiently used in determining optimal rehabilitation policies. Pareto optimal solutions obtained from multi-objective genetic algorithm can be used to obtain trade-off between cost and performance and avoid possible conflict between two decision policies.

Gravel aggregates had been used extensively in the Houston District of Texas Department of Transportation (TxDOT) for continuously reinforced concrete pavements construction for many years. However, some of these pavements have been subject to early age delamination and eventual spalling damage. Therefore, a series of studies funded by TxDOT since the early 1990's has been conducted to gain a better understanding of mechanisms, material properties, and construction practices, and to provide guidelines and recommendations for minimizing early-age delamination in concrete pavements made with gravel aggregates. In this study, a test protocol to measure the bond strength between aggregates and cement mortar was established, and the effects of different material and construction parameters on the bond strength of concrete at early ages using a fractional factorial design were investigated. The significances of each factor to achieve better bonding performance were determined, and the optimum design combination was subsequently chosen and validated. Geometric parameters were proposed to characterize aggregate shape properties relative to bonding performance with the facilitation of the Aggregate Imaging System. A rating system based on utility theory was developed to evaluate the overall contribution of aggregate properties (i.e. physical, geometric, and chemical) to the concrete bonding capability and the feasibility of certain mixture design combinations. As for theoretical representation of the bond strength across the interfacial transition zone, a model of interfacial fracture energy between aggregate and mortar that represents the energy necessary to create a crack along the interface was formulated. This model built the connection between concrete properties at the meso-level (represented by the interfacial fracture energy between aggregate and mortar) and the macro-level (represented by fracture toughness of concrete and significant influencing materials and construction factors). In addition, the moisture effects on stress development of concrete pavements at early ages using field data as inputs were numerically simulated, and a fracture mechanics-based approach was used to predict the occurrence of delamination. A delamination detection protocol for the field was developed to explore the feasibility and potential of utilizing Ground Penetration Radar technology in delamination detection. Research findings from laboratory investigation, field testing, theoretical modeling, and numerical analysis were further validated through field test sections, and the associated framework for delamination guidelines was established.

Thesis (M.S.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains ix, 70 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 43-45).

Thesis (M.S.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains vii, 65 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 52-53).

Thesis (Ph.D.) -- University of Texas at Arlington, 2008.