Alondra Chamorro

Current models and practices of economic and environmental evaluation for sustainable network-level pavement management

Ground transportation infrastructures, particularly road infrastructure, are essential for economic and social development. The quality level that the user perceives is mainly determined by the pavement condition. More than 400 billion dollars are invested globally each year in pavement construction and maintenance; these tasks increase by 10% the environmental impact generated by vehicle operation. Therefore, a sustainable approach should be incorporated in the assessment of preservation alternatives that consider technical, economic, environmental, political and institutional aspects in an integrated manner over their life-cycle. The purpose of the present research is to examine the models and practices for the economic and environmental evaluation of pavement assets, in order to analyze the advantages and limitations of the current state of the practice and identify the opportunities to improve their sustainable management. One of the main limitations identified is the lack of models that consider the economic and environmental aspects integrally. A need for models which consider the impact on users in work zones, as well as the use of new technologies and recycled materials that are more respectful of the environment, has been detected.

Development and Validation of a Method to Evaluate Unpaved Road Condition with Objective Distress Measures

The condition of unpaved roads is commonly assessed by using qualitative distress measures. Some methods do not consistently consider the relative effect of multiple defects on road condition, or their application is limited to the conditions under which they were developed. In 2007, the Ministerio de Obras Públicas of Chile and a private consultant developed the Modelos de Deterioro de Caminos No Pavimentados study. The scope of the study was to gain experience with and understanding of unpaved road behavior. The main goal of the study was to develop and validate a method for evaluating unpaved road condition by using objective measures of distress, drainage, and profile characteristics. The scope was to design a versatile tool that was applicable to any location, followed a simple procedure, and used cost-effective survey techniques. The proposed approach is to define condition models from a questionnaire administered to a professional panel by applying the Delphi method. As a result of the study, equations representing the unpaved condition index (UPCI) and condition limits were developed for unbound gravel, stabilized gravel, and earth roads subject to three climates: dry, Mediterranean, and humid. UPCI equations and condition limits were validated successfully; the method to assess unpaved road conditions was reliable and versatile.

Development of Distress Guidelines and Condition Rating to Improve Network Management in Ontario, Canada

In 2006, the Ministry of Transportation of Ontario, Canada (MTO), completed a study with the Centre for Pavement and Transportation Technology at the University of Waterloo to evaluate the performance of automated and semiautomated technologies that collect pavement distress data. From that study it was recommended that MTO define concise guidelines for surveying pavement distresses at the network level by using automated collection technologies and semiautomated distress analysis and for the guidelines to give special attention to quality assurance. In light of that recommendation, the study detailed in this paper presents the development of pavement distress guidelines and a distress manifestation index (DMI) for network-level (DMINL) evaluations by using automated collection technologies and semiautomated distress analysis. To define and validate DMINL, sections evaluated in the previous study were considered. The relative effect of each distress was obtained by linear regression and statistical analysis. The principle used to define the weighting factors was that the distresses considered by the new guidelines should quantify with a minimum error the DMI estimated by the MTO traditional method.

Development of a Management Framework for Rural Roads in Developing Countries: Integrating Socioeconomic Impacts

During the past decade, considerable efforts have been made to valuate the benefits of investments in rural roads in developing countries. Although the outputs of those studies have led to a global rethinking of traditional road appraisal methods, limited attempts have been made to integrate these findings into the rural road management process. The problem that arises from the analysis is a missing link between the appraisal of the socioeconomic impact and the management of rural roads. The main objective of the present study was to develop a methodology that combined all key aspects required for the sustainable management of rural roads in developing countries. For this, social, technical, economic, political, and sustainability aspects must be considered at the different levels of the management process. A case study developed in Chile is presented to illustrate the application of the proposed framework at the strategic and the network levels. From the application it was concluded that it was possible to combine in a practical and integrated tool all key factors affecting the process of management of rural roads in developing countries.

Calibration and Validation of Condition Indicator for Managing Urban Pavement Networks

Deterioration indexes that may combine types of surface distresses, serviceability, and structural indicators are commonly used for pavement management at the network level. These indexes differ in the types of deterioration and criteria considered to quantify severity and density of distresses. Most of these indexes were developed for interurban road networks; therefore, their application to urban networks is complex and not representative. For this reason, there is a need for a better understanding of urban pavement behavior to enable collection of the distresses relevant to these types of pavements and development of an overall condition index for urban pavements that represents the mix of the more relevant distresses for use in network analysis. This study is part of a 3-year project developed in Chile: Research and Development of Solutions for Urban Pavement Management in Chile. The main objective of this study was to calibrate and to validate an urban pavement condition index (UPCI) representative of the overall condition of these pavements, according to objective measures of surface distresses and evaluations of an expert panel. The scope of this study included the development of distress evaluation guidelines for asphalt and concrete pavements considering manual and automated surveys, the application of these guidelines in different types of urban networks, and the assessment of these networks by an expert panel. Finally, three UPCI equations were obtained with satisfactory validation for asphalt pavements with manual and automated data collection and for concrete pavements with manual data collection.

An iterative approach for the optimization of pavement maintenance management at the network level.

Pavement maintenance is one of the major issues of public agencies. Insufficient investment or inefficient maintenance strategies lead to high economic expenses in the long term. Under budgetary restrictions, the optimal allocation of resources becomes a crucial aspect. Two traditional approaches (sequential and holistic) and four classes of optimization methods (selection based on ranking, mathematical optimization, near optimization, and other methods) have been applied to solve this problem. They vary in the number of alternatives considered and how the selection process is performed. Therefore, a previous understanding of the problem is mandatory to identify the most suitable approach and method for a particular network. This study aims to assist highway agencies, researchers, and practitioners on when and how to apply available methods based on a comparative analysis of the current state of the practice. Holistic approach tackles the problem considering the overall network condition, while the sequential approach is easier to implement and understand, but may lead to solutions far from optimal. Scenarios defining the suitability of these approaches are defined. Finally, an iterative approach gathering the advantages of traditional approaches is proposed and applied in a case study. The proposed approach considers the overall network condition in a simpler and more intuitive manner than the holistic approach.

Condition Performance Models for Network-Level Management of Unpaved Roads

Unpaved roads may represent more than 80% of a countrys road network. Given the socioeconomic importance of unpaved roads to the well-being and development of rural populations, agencies in charge of their management should maintain them in optimum condition. A good management system should consider the use of effective evaluations of road conditions and reliable condition performance models. Available performance models for unpaved roads estimate the progression of one distress type subject to variations of independent variables affecting their performance over time. These variables commonly require detailed evaluations of road materials, geometric design, and traffic, demanding considerable expense and limiting the application of the models to project-level management. The objective of this study is to develop condition performance models for network-level management of unpaved roads on the basis of probabilistic deterioration trends observed in the field. The scope is to design practical models that are applicable to different climatic conditions and various road types and that can be effectively used by agencies in developing countries. The condition of an unpaved road network in Chile was assessed during three evaluation periods by use of the unpaved condition index methodology. Finally, condition performance curves for gravel and earth roads were developed with Markov chains and Monte Carlo simulation by consideration of a 10-year analysis period and three different climates.

Sustainable Pavement Management. Integrating Economic, Technical, and Environmental Aspects in Decision Making

Sustainability, which is founded on the reconciliation of economic, environmental, and social aspects, has become a major issue for infrastructure managers. The economic and environmental impacts of pavement maintenance are not negligible. More than

Validation and Implementation of Ontario, Canada, Network-Level Distress Guidelines and Condition Rating

400 billion are invested globally each year in pavement construction and maintenance. These projects increase the environmental impacts of vehicle operation by 10%. Because maintenance should be technically appropriate, infrastructure managers must integrate technical, economic, and environmental aspects in the evaluation of maintenance alternatives over the life cycle of a pavement. However, these aspects are normally assessed in measurement units that are difficult to combine in the decision-making process. This research examined and compared methods for the integrated consideration of technical, economic, and environmental aspects, and this study aimed to assist highway agencies, researchers, and practitioners with the integration of these aspects for the sustainable management of pavements. For this purpose, a set of maintenance alternatives for asphalt pavements was evaluated. Methods for the integration of these aspects were explored and led to recommendations for the most suitable methods for different scenarios. As a result of this analysis, the analytic hierarchy process (AHP) is recommended when the number of alternatives is small. In these situations, the AHP leads to results that are similar to those of the weighting-sum and multiattribute approaches that are frequently used for intuitive selection. However, when the number of alternatives is large, pair comparison becomes difficult with the AHP and the weighting-sum method becomes more appropriate.

Heuristic Optimization Model for Infrastructure Asset Management

The Centre for Pavement and Transportation Technology at the University of Waterloo and the Ministry of Transportation of Ontario (MTO) have been studying for the past 4 years the suitability of applying automated technologies for network-level evaluations in the province. Three projects have been developed for this purpose. The main results of these studies were a better understanding of available digital technologies, evaluation of the performance of semiautomated and automated technologies, development of new guidelines for pavement distress collection at the network level, design of an adjusted distress manifestation index, and recommendations for the use of semiautomated and automated digital technologies at the network level. The objective of this paper is to present the findings of the third and last phase of the project, Validation and Implementation of MTO Network Level Automated–Semiautomated Pavement Distress Guidelines and Condition Rating Methodology. The scope of the study was to validate and implement in the field MTO network-level distress guidelines and a distress manifestation index for network-level evaluations (DMINL), considering the use of automated technologies. A complete statistical analysis of data collected in the field through manual evaluations and semiautomated and automated technologies is presented. The performance of currently available technologies using network-level distress guidelines was assessed. Finally, from the field validation, distress guidelines were adjusted accordingly and DMINL equations were recalibrated.