The UK has adopted the concept of sustainable development and the construction industry is playing a key role in improving the efficient use of materials. The aim is to minimise the waste generated and maximise quantities of materials reused or recycled, minimising raw material consumption. Using Reclaimed asphalt pavement (RAP) is a rehabilitation technique which involves recycling materials from asphalt layers that have already been in service. This reduces the use of new bitumen and aggregates and avoids disposal. However, UK pavements constructed prior to 1980 or surfaced in the late 1980’s may contain tar, a carcinogenic substance that cannot be reheated and, therefore, cannot be recycled into hot mix asphalt (HMA). Recycling these pavements into unbound materials is also prohibited; consequently, disposal or cold recycling are the two available options. Cold recycling of asphalt is a proven technique that reduces material disposal and raw material and energy consumption. The reduction in energy consumption is largely achieved by avoiding aggregate drying and mixing of the material at ambient temperature. In this sense, using cold recycled bound materials (CRBMs) becomes the most economic and sustainable option. However, despite the increasingly common use of CRBM in roads, the specifications for the use of these materials in airfields are under-developed and there is no guidance to ensure that pavement design with these materials is trustworthy. This is the reason why this Thesis focuses on airfield pavement design with CRBM. The aim of this investigation is to develop a design methodology to use CRBMs in airfield pavements. For this purpose, the objectives were to review past experience on performance of these materials, measure and analyse the effect of key variables on performance to establish material limitations and develop a design methodology, proposing design guidance for airport authorities and practitioners. To achieve the project aims and objectives, a literature review was carried out focusing on pavement engineering, airfield pavement design and CRBM. The objective was to gain sufficient knowledge on key areas to conduct the research. Based on this literature review it was decided to use foamed bitumen as the cold technology and Kenlayer as pavement analytical design software. It was also found that the current design methodology for using CRBM in airfields is to conservatively equate material properties to those of a HMA commonly used in airfield base course (HDM50). Therefore, this practise should be analysed to decide if it is correct or if it can be improved. Subsequently, a laboratory programme was established to analyse CRBM mechanical properties and, therefore, understand the material’s behaviour and performance under cyclic loading. RAP, fly ash, cement and foamed bitumen were used to manufacture laboratory specimens, compacted with a gyratory compactor. These specimens were tested to analyse densities, air voids, stiffness, strength, permanent deformation and fatigue. For developing a new design methodology, Kenlayer was used to analyse strains and stresses within the airfield pavement. The first step was to ascertain Kenlayer adequacy and establish inputs related to loading, traffic and subgrade condition. For this purpose, 96 case studies were analysed with HMA, with different aircraft types, traffic and subgrade conditions. These cases were compared to those of a well-established airfield design guide, namely DMG 27. Then the software could be used to model pavements containing CRBM and with the knowledge gained in the laboratory about its behaviour, establish layer thicknesses to bear traffic during the pavement design life. With the results obtained from the laboratory investigation it was concluded that CRBM mixes have acceptable properties for use in airfield pavements. Resistance to permanent deformation, fatigue, temperature susceptibility and durability results show that these materials give reasonable performance; however, they differ from conventional hot mixes. Thus, current practice can be improved, justifying the need for design guidance for using CRBM in airfields. As fatigue is one of the main failure modes in asphalt mixtures and flexible pavements, a deeper study into fatigue behaviour of CRBM was carried out using Indirect Tensile Fatigue Tests (ITFT) in strain control mode and Wheel Track Test (WTT). The results showed different failure mechanisms for CRBM from those of HMA; thus, a new failure criterion was established. In HMA the failure criterion of 50% stiffness reduction is related to the appearance of macro cracks. CRBM develops dispersed micro-cracking that lowers the mixture stiffness without producing macro cracks until late in the material’s life. Macro cracks only tend to appear at 70% stiffness reduction; therefore, this was established as new failure criterion for CRBM. Once CRBM properties were defined, the pavement structure could be modelled. The results obtained from HMA modelling showed that the software and the inputs selected were appropriate for this investigation. Then the HMA base properties were substituted with CRBM properties obtained in the laboratory. The results showed that DMG 27, Chart 7, can be used for designing airfield pavements using CRBM increasing the base thickness by 9%, with a minimum Dry Lean Concrete (DLC) layer of 150 mm. A deterioration analysis was also carried out with the design software. In this case the aim was to analyse how strains distribute within the CRBM layer and how this affects the pavement life. With these analysis, it was highlighted how different CRBM behaves compared to HMA. Strains distributed linearly within the HMA layer; however, this does not happen with the CRBM. Moreover, this analysis showed how fatigue data can be used to obtain a more accurate pavement life taking into account different strain levels. Nevertheless, the study carried out here is based on laboratory performance of one type of CRBM. There is need for further investigation to establish a relationship between fatigue behaviour in the laboratory and the field and confirm how micro cracking affects the bearing capacity of the CRBM layer, establishing shift factors to optimise CRBM layer thickness. Moreover, the laboratory study has been carried out analysing CRBM in the same way as HMA; therefore, further study is needed to analyse the adequacy of the testing methodology. Also, modelling has been done comparing one CRBM to one HMA, namely HDM50; therefore, further investigation is needed to open the model to other HMA. Consequently, the design guidance presented here is a first step towards an airfield pavement design guide and further study is needed to optimise it.

Several thousand people die as a result of a road accident each year in Great Britain and the trend in the number of fatal accidents is monitored closely to understand increases and reductions in the number of deaths. Results from analysis of these data directly influence Government road safety policy and ensure theintroduction of effective safety interventions across the country. Overall accident numbers are important, but when disaggregating into various characteristics, accident risk (defined as the number of accidents relative to an exposure measure) is a better comparator. The exposure measure used most commonly for accident rate analysis is traffic flow which can be disaggregated into vehicle types, road type, and year. Here we want to assess the accident risk across different car types and car ages, and therefore alternative exposure sources are required. We disaggregate exposure to a further extent than possible with currently available data in order to take the increased variability within these new factors into account. Exposure data sources are mainly based on sample surveys and therefore have some associated uncertainty, however previous accident risk analysis has not, in general, taken this into account. For an explicit way to include this uncertainty we use a Bayesian analysis to combine three sources of exposure using a log-Normal model with model priors representing our uncertainty in each data source. Using further Bayesian models, we propagate this uncertainty through to accident rates and accident severity, determining important factors and inter- relationships between factors to identify key features affecting accident trends,and we make the first exploration of the effect of the recent recession on road accidents.

This research was designed to investigate the properties of aggregate with a new cement coating applied, and to test the effect of including this aggregate in a bituminous road mixture. The investigation was divided into three main areas of study. They were, chemical and physical testing of the aggregate, and testing of a bituminous road mixture containing the modified aggregate, namely porous asphalt wearing course. Chemical testing involved a regime to show the affinity between coated and uncoated aggregates, and bitumen, in terms of adsorption, and desorption in the presence of water. Physical testing included all the common tests for demonstrating the advantageous properties of an aggregate. These tests included, the shear box test, the polished stone value test, the aggregate crushing value test and tests for surface roughness. Porous asphalt was chosen as a suitable road material for testing the effects of the modified aggregate on a bituminous material, as it is a stone matrix dependant mixture and is currently enjoying increased acceptance Europe wide as a driver friendly, high quality surfacing material. Tests applied included the repeat load axial, and the repeat load indirect tensile tests. In order to undertake large parts of the testing program, much of the equipment was constructed by the researcher at Liverpool John Moores University (LJMU). This included the shear box apparatus and the repeat load axial test apparatus. These were both designed to the relevant British standards and verified as being so. Observations made during the testing programme showed the coated aggregates displayed a useful improvement in their chemical and physical properties over uncoated aggregates in almost all the areas tested. Future recommendations include mass production prototyping so that the coated aggregate mixtures can be placed in road trial sections.

Cold Bituminous Emulsion Mixtures (BEMs) means manufacturing of asphalt at ambient temperature using bitumen emulsion as the binder. It has been widely utilised in many countries such as the USA and France. The use and development of BEMs were not brought forward in the UK due to the country’s relatively wet/cold climatic conditions, which are not favourable to the application of cold BEM in terms of the long curing process and low early strength. Decreasing wastes from aggregate production processes, reducing land-filling and reducing CO2 emissions during hot bituminous mixture production and laying are the main target schemes for the environmentally friendly processes. Cold BEM is one of the attractive methods of producing bituminous mixtures to tackle the mentioned disadvantages when incorporating some waste and/or by-product materials individually or collectively into these mixtures. Recently, researchers have shown an increased interest in incorporating supplementary cementitious materials (SCM) in production of BEMs in the UK and around the world. Three benefits can be stated when using SCM in BEMs; these are upgraded mechanical properties, gaining economic advantage and the ecological advantage factor. Mainly due to some inherent problems associated with the performance of the pavement produced by the BEMs process, they are regarded as “inferior” to conventional HMA. The major problems with this kind of application are the long curing time (evaporation of trapped water) required to achieve the required performance, the weak early life strength (because of the existence of water) and high air voids content. The full curing in the field of these mixtures may occur between 2−24 months depending on the mixture’s ingredients and weather conditions. Considering the above disadvantages, this study investigated the possible ways of developing a new BEM/s with gap graded mixtures similar to the conventional Hot Rolled Asphalt (HRA) gradation. HRA is extensively used for surfacing major roads in the UK because it provides a dense, impervious layer, resulting in a weather-resistant durable surface able to endure the demands of today’s traffic loads and providing good resistance to fatigue cracking. The mentioned new product is termed Cold Rolled Asphalt (CRA). The main aim of this study was to investigate producing high strength, fast curing and sustainable CRA mixtures for heavily trafficked road and highway surfacing layers by using different waste and by-product materials (normally used as SCM) individually and/or collectively as a replacement for conventional mineral filler. To achieve the above aim, four SCMs have been used which were: Waste Paper Sludge Ash (WPSA), which has high lime and gelenite content, Poultry Litter Fly Ash (PLFA), which has high alkali components, Silica Fume (SF), and Rice Husk Ash (RHA), which is high silica content and cost-plus material, collectively instead of conventional mineral filler. In addition, besides the production of the new high-quality CRA mixtures, the research includes a detailed comparison study of conventional HRA mixtures, CRA mixtures containing conventional mineral filler and CRA mixtures containing hydraulic filler, i.e. Ordinary Portland Cement (OPC). This laboratory study was conducted by utilising different types of testing and curing and conditioning methods to characterise the mechanical properties and durability of the produced CRA mixtures. Indirect Tensile Stiffness Modulus (ITSM), Uniaxial Compression Cyclic Test (UCCT), Four Point Bending fatigue test on prismatic shaped specimens (4PB) and Semi-Circular Bending monotonic test (SCB) were used to assess the mechanical properties of these mixtures while Stiffness Modulus Ratio (SMR) and Long Term Oven Aging (LTOA) were used to investigate the main durability features, i.e. water sensitivity and long-term aging, respectively. Furthermore, Scan Electron Microscopy (SEM) technique and X-Ray Diffraction (XRD) analysis have been used to investigate the reasons behind the improvement in the mechanical properties of the novel mixtures. By means of ITSM results, four high-qualities CRA mixtures have been optimised which are: CRA-WPSA (containing 6% WPSA), CRA-BBF (containing 4.5% WPSA+1.5% PLFA), CRA-TBF-1 (containing 3.75% WPSA+1.25% PLFA+1% SF) and CRA-TBF-2 (containing 3.375% WPSA+1.125%PLFA+1.5% RHA). Stiffness modulus of CRA mixtures increases significantly by replacing the conventional mineral filler with WPSA, BBF, TBF-1 and TBF-2, especially in the early curing time (less than 7 days), which is the main disadvantage of the cold BEMs. Also, the target stiffness modulus, which is the ITSM for 100/150 HRA (approximately 2000MPa), was achieved after 4 hours for the produced fast-curing CRA mixtures, i.e. CRA-TBF-1 and CRA-TBF-2, under the normal curing method (24 hours in the mould then leave the samples at 20 ºC). In addition, the replacement of conventional mineral filler with WPSA, BBF, TBF-1 and TBF-2 greatly improves the permanent deformation resistance and fatigue life when compared with the control CRA and the traditional HRA mixtures.

The aim of this research project is to develop an improved backcalculation procedure, for the determination of flexible pavement properties from the Falling Weight Deflectometer (FWD) test results. The conventional backcalculation methods estimate the pavement layer moduli assuming full adhesion exists between layers in the analysis process. The method developed in this research can predict the interface condition between the wearing and the base courses in addition to the layer moduli, which can be considered an improvement to the existing procedures. A two stage database procedure has been used to predict the above parameters and to facilitate the determination of the deflection insensitive parameters. The need for this improvement arises from the large number of debonding failures which have been reported in the literature between the wearing and base courses, and the theoretical studies which identified the significance of including the interface bonding condition in the analysis process. The validation of the improved method has been carried out firstly by comparing the backcalculated results for ninety theoretical pavements with their hypothetical values, and secondly by comparing the improved procedure results with other well known programs such as WESDEF and MODULUS. Full scale pavement testing using the FWD has been performed and the backcalculated results compared with measured values for the pavement materials. Indirect tensile tests for resilient modulus of bituminous materials were carried out on cores extracted for the pavements, whereas Dynamic Cone Penetrometer (DCP) tests were conducted for the unbound materials. The Backcalculated and the physically measured results correlated well, validating the improved procedure.

The continuous implementation of highly technological functions and specifically intelligent transport systems in public transport highlights the need of highly efficient, accurate and reliable bus operations network. Intelligent transport systems can support a variety of functions, including dynamic bus fleet management which has yet to be established in most bus fleets in the UK in a systematic way. In order to support dynamic bus fleet management by detecting the fundamental role of bus and traffic incidents in bus-based public transport, a microscopic simulation model capable of modelling the impact of the individual incidents‟ characteristics on bus operations has been developed and applied to a variety of scenarios. This research draws on a review of existing literature on bus fleet management and available computer software in this field. It investigates research gaps in modelling the impact of traffic incidents on overall bus performance; it describes the design and development of the new simulation model, SIBUFEM (Simulating Incidents for Bus Fleet Management) for modelling bus operations during whole day periods in which incidents of different types can occur. The model simulates a high frequency bus service using existing field data and incorporates the continuous circulation of buses along the bus route. It uses journey time profiles, passenger-dependent bus stop dwell times and deterministic time-dependent queuing theory to model traffic incidents and the impact of their characteristics on the bus performance parameters. The model results, presented in this thesis, focus on performance measures including but not limited to bus journey times, passenger waiting times and bus delays resulting from various bus and traffic incidents. Incidents vary from bus breakdowns, to traffic incidents such as road-works, traffic accidents, burst water mains, disabled vehicles and illegal parking; in SIBUFEM they are specified in terms of their location, duration and severity (i.e. loss of capacity). The model has been applied to a main bus corridor in Southampton, UK, with a base case of „normal‟ operations established, for comparison with results from 24 different incident scenarios, and using key model performance parameters of average bus journey time, bus speed and excess waiting time. This PhD demonstrates the functionality of SIBUFEM with model results demonstrating the extent to which passenger waiting times increase with increasing incident severity and duration. The overall comparison of the simulation results showed that the more severe the level of severity or the longer the duration of an incident, the higher the expected impact of the event on the overall bus performance was. In terms of the incident location parameter, the effect is greater when the incident occurs in the middle of the bus route than when it occurs at the end. The effect of incident location is especially evident in the case of traffic incidents such as roadworks, traffic accidents and illegal parking. Findings from this research also demonstrated that these incidents are usually more severely affected by a change in an incident parameter than by bus breakdown incidents. The thesis concludes with a discussion on potential dynamic bus fleet management strategies and how SIBUFEM can be further developed to allow these strategies to be evaluated. SIBUFEM is capable of modelling traffic incidents to support dynamic bus fleet management and, thus, encourage the use of intelligent transport systems applications in bus operations. This offers great potential in the field of bus-based public transport as part of a guidance tool for bus operators, as well as the way to increase bus level service thereby increasing customer satisfaction and thus the development of a sustainable transport system.

The population and economy in the State of Qatar have been increasing significantly in the past 10 years. Accordingly, traffic loading has also increased rapidly, which merits consideration of the design and construction of long-lasting pavement structures that require minimal maintenance. This study started with an investigation of the feasibility and performance of the current asphalt pavement materials and structures being used in the country. This investigation utilised the analysis approach implemented in the Mechanistic-Empirical Pavement Design Guide (M-E PDG) software. The results evidenced how effective it is to replace the conventional unmodified 60-70 Pen bitumen with polymer-modified PG76-10 bitumen for pavements in Qatar and other countries in the region with similar climatic conditions. In addition, the results showed that the use of perpetual pavement structures is a viable option economically and that they are much more accommodating of increase in traffic loading, without causing excessive damage, than conventional pavement structures. The study also concentrated on the assessment of the long-term performance of different full-scale perpetual trial sections by conducting several field tests. The field performance evaluation results showed slightly low resistance to rutting, high IRI values, to some extent, and low stiffness during summertime when the temperature is high. These distresses and deteriorations are expected given the huge traffic loading and the big difference in temperature between seasons in Qatar. Then several field cores, field mixtures, and laboratory mixtures were tested and evaluated in order to assess the performance of different asphalt concrete mixtures against rutting, fracture, temperature susceptibility and fatigue damage. The conducted tests were useful to characterise and assess the performance of the mixtures against several major distresses. The results indicated that resistance of asphalt concrete mixtures to rutting was mainly affected by the bitumen grade, aggregate source and aggregate gradation. A well-designed mixture that uses polymer-modified bitumen (PMB) can achieve the high rut-resistance of asphalt mixtures either with Gabbro or limestone aggregates. The use of polymer-modified bitumen reduced the temperature and frequency susceptibility on the stiffness and rut-resistance. According to these results, it is obvious that rutting and cracking would not be major distresses for asphalt mixtures in Qatar if the mixtures were designed following a Superpave mix design with the appropriate content of polymer-modified bitumen. However, given the current mixture design system in Qatar, which utilises very low bitumen content, fatigue damage or cracking in general is a main distress, and its characterisation should be investigated in depth. The traditional methods to interpret fatigue tests data are not sufficient to characterise and evaluate mixtures against fatigue damage. Therefore, two advanced fatigue characterisation approaches were performed on the raw data obtained from the fatigue test of specimens prepared from different mixtures. The analysis of the fatigue tests focused on calculating the dissipated energy (DE) and obtaining damage characteristics curves following a comprehensive viscoelastic continuum damage (VECD) approach. The test results showed that the use of the VECD approach has major advantages over obtaining DE results only. However, the predicted fatigue life (Nf) for each asphalt mixture was affected by the uncertainty associated with fatigue tests as well as with model parameters. Therefore, it was important to develop a probabilistic analysis approach that accounts for the uncertainty and the variability associated with fatigue tests and analysis, respectively. To that end, a novel probabilistic analysis approach has been proposed in the last chapter of this study for predicting the performance of asphalt mixture against fatigue damage. The VECD characterisation approach was used in the development of this probabilistic analysis model. The random variables (RVs) of the fatigue life (VECD-Nf) model (|E*|LVE, a, b and α) were generated following normal distribution functions. However, it is suggested that more specimens should be tested in the future to specify the true distribution functions for the RVs. In conclusion, it is clear that the fatigue life results of the probabilistic analysis approach were much more consistent and reliable than those of the deterministic analysis approach. This probabilistic approach coupled with VECD results is very practical and useful for engineers and will be beneficial to predict fatigue cracking resistance of asphalt mixtures in the field.

After natural/man-made disasters, a major challenge faced by governments is to ensure a speedy recovery of roads and transportation networks. In order to achieve this, a new road recovery priority (RRP) model has been developed to identify key issues and their inter-relationships giving a better understanding of factors that govern prioritisation across the affected regions. Interviews are conducted with experts in road reconstruction and maintenance organisations to investigate respondents’ evaluation and understanding of the RRP model in terms of its ease of use, usefulness, comprehensiveness, applicability, feasibility and structure. A questionnaire survey is conducted to investigate the impact of the important proposed affecting factors that can be critical for successful implementation and application of the RRP model in the road rehabilitation sector. A field survey is carried out to collect data which are essential to determine parameters in the model’s application. Four case studies are carried out to investigate the RRP model’s application in a variety of road conditions. The application of this model may solve the problem of decision making in road recovery priority determination in a hierarchical manner so that the recovery process can be accomplished from an urgent repair need to a lower recovery priority.

Transportation is a central component to most political, economic, social and environmental issues throughout most inhabited societies. The concerns of transport have become widely acknowledged. It is broadly accepted that promoting alternative forms of transport such as walking, cycling and public transport use is one solution to tackle environmental concerns. Although, delivering, implementing and developing transport strategies to reduce car usage is still highly debated. Transport stakeholders (e.g. planners and policymakers) have long strived to reduce car usage. Many studies have attempted to develop strategies or understand triggers that might encourage and promote a reduction in car use. Despite this, the car usage has typically intensified and alternative forms of transport have become marginalised or discouraged when compared to the car. This research investigates travel attitudes and behaviours of individuals along a specific urban travel corridor within an area of Birmingham, UK. It explores socio-demographic factors using a mixed methods approach that incorporated questionnaires, travel diaries and interviews. This work identified a series of transport measures conceived upon different urban demographic characteristics in order to meet different individuals’ transport need. A significant finding from this work indicated there was an appetite amongst the sampled participants to be willing to reduce their car use if the right transport strategies were introduced. Initially the results from the questionnaire suggested age influenced car use the most, however, other demographic characteristics (e.g. gender and deprivation) were found to be an influential factor.

The research was aimed at the development of an optimal road fund allocation model for road maintenance to three road agencies in Ghana. The objective was to compare a novel model by multicriteria analysis (MCA) with deterministic outcome and a model based on preferential analysis to determine optimality. The deterministic model was efficiency based with quantitative analysis from a decision maker’s perspective whilst the approach by preferential analysis was equity based with qualitative analysis from stakeholder perspective. The input parameters of the deterministic model were based on the value function method (VFM) and the concept of efficiency frontier. It determined a scaler index for the proportionate allocation of road fund by road type. It was based on a set of attributes including road length, traffic, pavement roughness and percentage of work achievement. The concept of efficiency frontier was used to sub divide the proportion of funds allocated by road type into economic efficiency and equity components based on the Net Present Value/Capital, Vehicle Operation Cost (VOC) and income. The values of the selected attributes were generated from the outputs of HDM-4 analysis. The model based on the preferential analysis was set on the Analytical Hierarchy Process (AHP). It involved pairwise comparison of defined criteria and sub criteria by stakeholder priority at national, district and community levels. Priority vectors were estimated for road fund allocation into efficiency and equity proportions by road type. A comparison of the outputs of the two models on the basis of the impact on pavement roughness performance indicated the stated preference based model yielded better impacts than the model with deterministic approach. It was concluded that road fund allocation based on a well logically determined value judgement with mathematical analysis yields better results.