Faced with continuously increasing maintenance due to aging infrastructure, the Texas Department of Transportation (TxDOT) is evaluating the potential impact of reduced funding on highway safety. The main objective of this thesis is to develop a methodological procedure to identify threshold levels of pavement skid resistance for highways in the context of traffic crashes, assisting TxDOT Administration and engineers in making proper maintenance decisions. As a result, the efficiency and safety of the highway system could be preserved. The scope of this study covers all types of state-maintained highways in Texas. The primary objectives of this thesis include: 1) synthesis of literature; 2) quantification of the relationship between crash risk and pavement skid resistant; 3) determination of critical skid resistant threshold levels; and, 4) benefit cost analysis. A detailed methodology framework was developed and a comprehensive database was generated from four data files containing pavement, geometry, traffic, and crash information to support this research. The impact of skid resistance level on crash risks was proven to be significant based on the results of regression analysis and insights provided by TxDOT experts. The quantitative relationships between crash risk and skid resistance were quantified using the Crash Rate Ratio method. Hierarchical structure grouping was used to categorize the entire network into homogeneous groups based on traffic level, roadway alignment and other factors. Critical skid resistance threshold levels were determined for the whole state as well as for stratified highway groups. Finally, benefit/cost ratio analyses were conducted to evaluate the effectiveness of pavement maintenance treatments to restore or increase skid resistance. / text

Highway agencies usually face budget uncertainty for pavement maintenance and rehabilitation activities due to limitation in resources and changes in government policies. Highway agencies perform maintenance planning for the pavement network commonly based on the nominal available budget without taking the variability of budget into consideration. The maintenance program based on deterministic budget consideration results in suboptimal maintenance decisions that impact the overall network conditions, if the budget falls short in some future year in the planning horizon. As a result, it is important for highway agencies to adopt maintenance and rehabilitation policies that are protected against the uncertainty in maintenance and rehabilitation budget. In this study a multi-period linear integer programming model is proposed with its robust counterpart considering uncertain maintenance and rehabilitation budget. The proposed model is able to provide a maintenance and rehabilitation program for the pavement network that results in minimal impact of budget variability on the network conditions. A case study was carried out for a network of ten pavement sections. The solution of the robust optimization model was compared to those with deterministic model. The results show that the robust optimization model is an attractive method that can minimize the effect of budget uncertainty on pavement conditions at the network level. / text

The traditional method of repairing damaged roads in Atlantic Canada has been to place a hot mix asphalt overlay over the existing road. Though this method provides a new, smooth wearing surface to drive on, it is merely a short term fix. With time, the cracks in the original pavement will reflect to the surface of the new pavement, resulting in failure of the overlay. An alternative option gaining more prominence is the use of a Full Depth Reclamation (FDR) technique, which involves pulverizing the flexible pavement, along with a portion of the underlying layer. This material is then stabilized and recompacted to produce a new base layer that is free of damage. Though FDR has been used for a number of years, there are still problems with variability in the strength of the materials in some projects. It is hypothesized that some of these problems are due to variability and poor quality in the reclaimed materials. It is believed that current pulverization methods contribute to the variability being observed in these materials. Two FDR projects employing different pulverization control methods were studied to examine how the consistency of the reclaimed materials can be improved through the use of a Ground Penetrating Radar (GPR) survey to map the variability in the depth of the pavement. Controlling the thickness ratio of asphalt concrete to granular base materials being pulverized was shown to improve the consistency of materials, properties, and performance. The second phase of this research project studied how improving the gradation of the reclaimed materials with the addition of a crusher dust might result in improved performance of stabilized base materials, in this case stabilized with expanded asphalt. The effect of construction variability on the improved materials was also studied by varying both the moisture content, and asphalt content from optimum conditions, as might be expected during construction. Results indicated that the quality of the stabilized FDR materials can be significantly improved by bringing the material gradation closer to the theoretical maximum density gradation. The performance of the stabilized materials can be affected by both the mixing moisture content, and the asphalt content used during stabilization. This suggests that effective quality control, and stricter specifications on the constructed product would result in more reliable, effective FDR pavements. / A study on the control of the consistency of pulverized FDR materials, as well as a study examining how to improve the performance of these pulverized materials.

The AASHTO 1993 Guide for Design of Pavement Structures is the most widely used pavement design method in both Canada and the United States, and is currently used by the Ministry of Transportation of Ontario (MTO) for both flexible and rigid pavement design. Despite its widespread use, the AASHTO 1993 pavement design method has significant limitations stemming primarily from the limited range of conditions observed at the AASHTO Road Test from which its empirical relationships were derived. The Mechanistic-Empirical Pavement Design Guide (MEPDG) was developed to address the perceived limitations of the AASHTO 1993 Guide. Although the MEPDG provides a rational pavement design procedure with a solid foundation in engineering mechanics, a considerable amount of work is required to adapt and validate the MEPDG to Ontario conditions. The purpose of this research was to conduct a comparative analysis of Ontario structural pavement designs using the AASHTO 1993 Guide for Design of Pavement Structures and the Mechanistic-Empirical Pavement Design Guide. Historical flexible, rigid, and asphalt overlay pavement designs completed using the AASHTO 1993 pavement design method for the MTO were evaluated using a two-stage procedure. First, the nationally-calibrated MEPDG pavement distress models were used to predict the performance of the pavements designed using the AASHTO 1993 method. The purpose of this stage of the analysis was to determine whether the two methods predicted pavement performance in a consistent manner across a range of design conditions typical of Ontario. Finally, the AASHTO 1993 and MEPDG methods were compared based on the thickness of the asphalt concrete or Portland cement concrete layers required to satisfy their respective design criteria. The results of the comparative analysis demonstrate that the AASHTO 1993 method generally over-predicted pavement performance relative to the MEPDG for new flexible pavements and asphalt overlays of flexible pavements. The MEPDG predicted that most of the new flexible pavements and asphalt overlays of flexible pavements designed using the AASHTO 1993 method would fail primarily due to permanent deformation and / or roughness. The asphalt layer thicknesses obtained using the MEPDG exceeded the asphalt layer thicknesses obtained using the AASHTO 1993 method, and a poor correlation was observed between the asphalt layer thicknesses obtained using the two methods. Many of the new flexible pavements and asphalt overlays of existing flexible pavements could not be re-designed to meet the MEPDG performance criteria by increasing the asphalt layer thickness. The results of the comparative analysis showed that the AASHTO 1993 method generally under-predicted rigid pavement performance relative to the MEPDG, although the results varied widely between alternative rigid pavement designs. The AASHTO 1993 rigid pavement designs that the MEPDG predicted would not meet the rigid pavement performance criteria generally failed due to pavement roughness. A very poor correlation was observed between the Portland cement concrete layer thicknesses obtained using the MEPDG and AASHTO 1993 design methods. The MEPDG predicted thinner Portland cement concrete layer thicknesses than the AASHTO 1993 design method for most of the rigid pavement designs.

No description available.

This dissertation is concerned with the principles of pavement management systems and their applications in western and developing countries. The first part of the dissertation deals with the principles of pavement engineering and the role of the different layers in order to gain the required knowledge in highway pavement components, which will allow a cost-effective repair related to each specific defect. The second part deals with the existing systems for monitoring pavement condition and evaluatest heir benefit in assessingh ighway condition. The study shows the main problems usually militate against using the sophisticated technology in monitoring highway condition and implementing maintenance management systems in some cities in developing countries. In addition to the problems inherent in cities in developing countries, the city of Benghazi in Libya has special factors which have developed as a result of UN sanctions which were imposed in 1992. Therefore, the city of Benghazi has been selected as a case study for this particular research since it is a typical example of most cities in developing countries in terms of size, population and in ten-ns of lack of maintenance resources and skilled labour (Benghazi might have been so well resourcedth at it would no longer fall into the categoryo f developingc ity but for the sanction). The objectives of the study are attained through conclusions which indicate that establishing a pavement maintenance strategy in the city of Benghazi based on any or some of the sophisticated technology in road condition monitoring is not appropriate. This conclusion is tested by manufacturing a unique prototype measuring machine and using it in pilot monitoring exercises in the cities of Newcastle and Sunderland. The results of these pilot exercises are analysed to evaluate the benefit which such appropriate technology equipment can bring to the issue of monitoring of pavement condition in cities in developing countries having problems similar to those that prevail in Benghazi. The prototype equipment developed in this study is unique in that it is purely mechanical and uses no electronics in monitoring road condition. Moreover, all parts of the machine are fabricated from materials available in most cities in developing countries and therefore such machines could be easily maintained locally. The prototype described in this study is not only relevant to road monitoring but points the way towards the development of similar equipment in many engineering situations in developing countries. This research study points engineers in similar conditions in the direction that the Author thinks they should follow in applying their engineering abilities in developing countries.

Pavement markings, as a form of traffic control devices, play a crucial role in safely guiding drivers. Restriping pavement markings is an important task in the maintenance of traffic control devices. Every year state agencies spend a lot of money in maintaining pavement markings as the retroreflectivity or durability values of the markings fall below a minimum level. Currently, the most widely adopted method used to determine the presence conditions of pavement markings is by expert observation, a subjective technique that may not provide consistent and convinced results for agencies. Hence, a fast and accurate way to determine the presence conditions of pavement markings can lead to significant cost savings while ensuring driving safety. In this study, a systematic approach that can automatically determine the presence conditions of pavement markings using digital image processing techniques is presented. These techniques are used to correct the geometric deformity, detect colors of pavement markings, segment images, enhance images, detect edge lines of ideal pavement markings, and recognize the features of pavement markings appearing in the photographs. To better implement the aforementioned techniques, a software package has been developed by Graphic User Interface (GUI) as a platform to simultaneously evaluate the presence conditions of single or multiple pavement markings. The developed software package is able to do operations such as open files, calibrate camera calibration, clip, rotation, histogram display, and detection of edge lines of ideal pavement markings. The above system was tested and evaluated with the photograph datasets provided by the NTPEP Mississippi test deck. The empirical results (when compared with the manual method and expert observation) show that the developed system in this study is accurate and reliable. Additionally, the interactivity of the developed software package is satisfactory due to the feedback from ten volunteers. It is also concluded that the developed system, as an important reference, potentially helps agencies make a better decision in the maintenance of pavement markings with more accurate and speedy evaluation of the presence conditions of pavement markings.

abstract: Deterministic solutions are available to estimate the resilient modulus of unbound materials, which are difficult to interpret because they do not incorporate the variability associated with the inherent soil heterogeneity and that associated with environmental conditions. This thesis presents the stochastic evaluation of the Enhanced Integrated Climatic Model (EICM), which is a model used in the Mechanistic-Empirical Pavement Design Guide to estimate the soil long-term equilibrium resilient modulus. The stochastic evaluation is accomplished by taking the deterministic equations in the EICM and applying stochastic procedures to obtain a mean and variance associated with the final design parameter, the resilient modulus at equilibrium condition. In addition to the stochastic evaluation, different statistical analyses were applied to determine that the uses of hierarchical levels are valid in the unbound pavement material design and the climatic region has an impact on the final design resilient moduli at equilibrium. After determining that the climatic regions and the hierarchical levels are valid, reliability was applied to the resilient moduli at equilibrium. Finally, the American Association of State Highway and Transportation Officials (AASHTO) design concept based on the Structural Number (SN) was applied in order to illustrate the true implications the hierarchical levels of design and the variability associated with environmental effects and soil properties have in the design of pavement structures. The stochastic solutions developed as part of this thesis work together with the SN design concept were applied to five soils with different resilient moduli at optimum compaction condition in order to evaluate the variability associated with the resilient moduli at equilibrium condition. These soils were evaluated in five different climatic regions ranging from arid to extremely wet conditions. The analysis showed that by using the most accurate input parameters obtained from laboratory testing (hierarchical Level 1) instead of Level 3 analysis could potentially save the State Department of Transportation up to 10.12 inches of asphalt in arid and semi-arid regions. / Dissertation/Thesis / M.S. Civil and Environmental Engineering 2011

Esta dissertação trata do desenvolvimento de um protótipo de Sistema de Gerência de Pavimentos para a rede de aeroportos militares administrados pelo Comando da Aeronáutica (COMAER) e apresenta uma metodologia para a execução da Gerência de Pavimentos no âmbito do COMAER, a fim de subsidiar a elaboração do Plano Plurianual de Obras da Aeronáutica. Para tanto, foram levantadas as informações disponíveis, bem como o inventário de pavimentos das bases aéreas subordinadas ao Quinto Comando Aéreo Regional (V COMAR), o histórico de condição e de intervenção dos pavimentos dos últimos 5 anos, dados de projeto, custos e tráfego aéreo e, a partir desses elementos e de indicações do desempenho dos pavimentos estudados, foi elaborada uma proposta plurianual de investimentos em termos de obras de conservação, a fim de prolongar a vida útil dos mesmos, permitindo um aproveitamento mais racional dos recursos existentes. Além disso, para integrar as informações fragmentadas entre os diversos elos do Sistema de Engenharia espalhados pelo Brasil, foi desenvolvido um Sistema de banco de dados para possibilitar a consulta e cadastramento das avaliações através da INTRAER, a rede interna do Comando da Aeronáutica. / This dissertation concerns in the development of a prototype of a preliminary Pavement Management System for the network of military airports managed by the Brazilian Air Force (COMAER) and aims to provide a methodology for the implementation of the pavement management within the Brazilian Air Force, in order to support the development of the multi-year plan of works. To do it so, the existing information system and the inventory of airfields pavements subject to the Fifth Regional Air Command (COMAR V) was raised, the history of the condition and intervention of decks in the past five years, project data, costs, air traffic and from these elements and performance measures of the pavements studied was an elaborate multi-year investment proposal in terms of conservation works in order to extend the pavement life wich aim at a more rational utilization of resources. In addition, to integrate the fragmented information between the various links of Engineering System throughout Brazil, it was developed a database system to enable to consult and register evaluations through the INTRAER, the internal network of the Brazilian Air Force.

The sources of natural or virgin coarse aggregates are diminishing in alarming rate and its production is quite expensive, uses a lot of energy, and is not environmental friendly. Hence, utilizing the recycled aggregates like reclaimed or recycled concrete aggregate (RCA) and recycled asphalt pavement (RAP) on road pavement will not only preserve the natural aggregates but also reduce the negative environmental impact. It also helps to conserve the waste landfill sites. The major downside for the use of the recycled aggregate is the quality control during its production. This research characterizes RCA samples obtained from a demolished old foundation and RAP samples from old parking lot and determines their suitability as road pavement materials. Virgin aggregates, recycled aggregates, and several blended mixtures with 20 to 80% replacement of natural coarse aggregate or virgin aggregate (NCA or VA) by weight with RCA and RAP were prepared and tested for resilient modulus (Mr) and California Bearing Ratio (CBR) test. The durability of the virgin aggregate and recycled aggregate were also determined by micro-deval test. The resilient modulus value of 100% RCA and 100% VA was found to be very similar or higher but for 100% RAP the resilient modulus is higher than that of the 100%VA. The Resilient modulus of the RAP blended mixtures increases with the increase in the content of RAP percentage and for the RCA it was not consistent. The CBR values for the blended mixtures decreases with the increase in the percentage of the recycled aggregates. The micro-deval degradation test result for RCA was more than of VA due to presence adhere materials in RCA.