Optimización heurística multiobjetivo para la gestión de activos de infraestructuras de transporte terrestre

[EN] Despite the importance of infrastructure in economic and social development, available funds for their maintenance are often insufficient, leading to a rapid deterioration. In this context arises the discipline of infrastructure asset management. By combining engineering principles with business practices and economic theory, infrastructure asset management enables an optimal resource allocation for the operation of infrastructure over its lifecycle. Traditionally, the evaluation of maintenance alternatives has been focused in economic and technical terms. Recent efforts have been made to quantify the environmental impact of these activities. However, current models lack of an integrated evaluation. This limitation creates the need to develop a sustainable evaluation of maintenance alternatives that integer technical, economic and environmental aspects over the infrastructure life-cycle. With respect to the allocation of maintenance funds, optimization methods mainly used are mathematical programming and near-optimization methods. Regarding near-optimization methods, too little attention has been paid to heuristic algorithms, which so far have only been applied to solve the problem at the project level. In addition, optimization applications in infrastructure management are mainly focused on one objective, ignoring thus the complex and multi-objective nature of the real problem. There is an opportunity to develop a heuristic multi-objective optimization tool that, considering a sustainable evaluation of alternatives, improves the current allocation of maintenance resources. In view of this background, the main objective of this research is to develop a tool for the sustainable evaluation of maintenance alternatives and the multi-objective heuristic optimization. This tool enables a more sustainable and efficient allocation of available resources for the maintenance of infrastructure at the network level. This tool is applied to a case study dealing with the management of an urban pavement network in Chile. This research concludes that the heuristic algorithms based on local search heuristics are inefficient to solve the budget allocation problem. Given this limitation, a new hybrid method is developed. It combines GRASP (Greedy Randomized Adaptative Search Procedure), GLS (Guided Local Search) and GFB (Greedy First Best) algorithms. Moreover, it evaluates the maintenance alternatives considering, in an integrated manner, technical, economic and environmental aspects. The proposed hybrid algorithm results in maintenance programs with an average effectiveness that is 9% higher than the one obtained with local search heuristics. The hybrid algorithm also requires in this process a lower computational effort. The application of the optimization tool to the Chilean case study improves the current management of urban pavements. The average network condition is 22% higher than the one obtained under the current practices and the generated CO2 emissions are reduced in 12%. In practical terms, optimal programs consider a proactive maintenance policy. This policy applies preservation treatments when the pavement condition is still good. Finally, the optimization tool produces in this research enables a better planning of maintenance funds over time. Based on the evidence demonstrated by the Chilean case study, it is concluded that the funding level over time is a key factor in the technical and environmental performance of the network.[ES] A pesar de la importancia de las infraestructuras en el desarrollo económico y social, los recursos disponibles para su conservación suelen ser insuficientes, generando un deterioro acelerado de las mismas. En este contexto surge la disciplina de gestión de activos de infraestructura, que busca optimizar la asignación de recursos para la gestión, operación y conservación de la infraestructura mediante un análisis de su ciclo de vida. Los criterios tradicionalmente empleados para evaluar las alternativas de conservación han sido los técnicos y económicos. Si bien, recientemente, se han realizado esfuerzos para cuantificar el impacto ambiental; los modelos actuales carecen de un enfoque integrado. Surge así la oportunidad de desarrollar una evaluación sostenible que integre los aspectos técnicos, económicos y ambientales en el ciclo de vida de la infraestructura. En relación a la asignación óptima de recursos, los métodos mayoritariamente empleados son los de programación matemática y los métodos de optimización aproximada. Dentro de estos últimos, las aplicaciones de algoritmos heurísticos resultan escasas, limitándose a resolver el problema a nivel de proyecto. Estos métodos, sin embargo, han sido exitosamente aplicados para resolver problemas de optimización combinatoria en otros campos de investigación. A esto hay que añadir que las aplicaciones desarrolladas se centran, mayoritariamente, en la optimización de un único objetivo; obviando la naturaleza multiobjetivo del problema real. Se detecta, por tanto, la oportunidad de desarrollar una herramienta de optimización heurística multiobjetivo que, considerando una evaluación sostenible de alternativas, mejore la asignación actual de recursos. A la vista de estos antecedentes, el objetivo principal de esta investigación consiste en desarrollar una herramienta para la evaluación de alternativas de conservación y la optimización heurística multiobjetivo, que permita una asignación más sostenible y eficiente de los recursos disponibles para la conservación de redes de activos de infraestructura de transporte terrestre. La herramienta propuesta se aplica a un caso de estudio real que consiste en la gestión de una red de pavimentos urbanos en Chile. De la aplicación de la herramienta de optimización al caso de estudio se concluye que los algoritmos heurísticos basados en búsquedas por entornos resultan poco eficientes para resolver el problema de asignación de recursos de conservación. Ante esta limitación, se desarrolla un nuevo método híbrido que considera los algoritmos GRASP (Greedy Randomized Adaptative Search Procedure), GLS (Guided Local Search) y GFB (Greedy First Best). Además, el método propuesto permite evaluar las alternativas de conservación considerando, de forma integrada, criterios técnicos, económicos y ambientales. El algoritmo híbrido propuesto diseña programas de conservación con una efectividad media un 9% superior a la obtenida con el algoritmo de búsqueda por entornos más eficaz, requiriendo para ello un menor esfuerzo computacional. En la aplicación al caso de estudio chileno, se observa que el algoritmo híbrido mejora la gestión actual, aumentando en un 22% la condición media de la red y reduciendo, además, las emisiones de CO2 en un 12%. En términos prácticos, los programas óptimos consideran una política proactiva, en la que los pavimentos se tratan cuando la condición de los mismos aún es buena. Por último, la herramienta propuesta mejora la planificación temporal de los recursos. En base a las evidencias demostradas en el caso de estudio, se concluye que la distribución temporal del presupuesto es un factor clave en el desempeño técnico y ambiental de la red.[CA] A pesar de la importància de les infraestructures en el desenrotllament econòmic i social, els recursos disponibles per a la seua conservació solen ser insuficients, generant un deteriorament accelerat de les mateixes. En este context sorgix la disciplina de gestió d'actius d'infraestructura, que busca optimitzar l'assignació de recursos per a la gestió, operació i conservació de la infraestructura per mitjà d'una anàlisi del seu cicle de vida. Els criteris tradicionalment empleats per a avaluar les alternatives de conservació han sigut els tècnics i econòmics. Si bé, recentment, s'han realitzat esforços per a quantificar l'impacte ambiental; els models actuals no tenen un enfocament integrat. Sorgix així l'oportunitat de desenrotllar una avaluació sostenible que integre els aspectes tècnics, econòmics i ambientals en el cicle de vida de la infraestructura. En relació a l'assignació òptima de recursos, els mètodes majoritàriament empleats són els de programació matemàtica i els mètodes d'optimització aproximada. Dins d'estos últims, les aplicacions d'algoritmes heurístics resulten escasses, limitant-se a resoldre el problema a nivell de projecte. Estos mètodes, no obstant això, han sigut reeixidament aplicats per a resoldre problemes d'optimització combinatòria en altres camps d'investigació. A açò cal afegir que les aplicacions desenrotllades se centren, majoritàriament, en l'optimització d'un únic objectiu; obviant la naturalesa multiobjetivo del problema real. Es detecta, per tant, l'oportunitat de desenrotllar una ferramenta d'optimització heurística multiobjetivo que, considerant una avaluació sostenible d'alternatives, millore l'assignació actual de recursos. A la vista d'estos antecedents, l'objectiu principal d'esta investigació consistix a desenrotllar una ferramenta per a l'avaluació d'alternatives de conservació i l'optimització heurística multiobjetivo, que permeta una assignació més sostenible i eficient dels recursos disponibles per a la conservació de xarxes d'actius d'infraestructura de transport terrestre. La ferramenta proposada s'aplica a un cas d'estudi real que consistix en la gestió d'una xarxa de paviments urbans a Xile. De l'aplicació de la ferramenta d'optimització al cas d'estudi es conclou que els algoritmes heurístics basats en busques per entorns resulten poc eficients per a resoldre el problema d'assignació de recursos de conservació. Davant d'esta limitació, es desenrotlla un nou mètode híbrid que considera els algoritmes GRASP (Greedy Randomized Adaptative Search Procedure) , GLS (Guided Local Search) i GFB (Greedy First Best) . A més, el mètode proposat permet avaluar les alternatives de conservació considerant, de forma integrada, criteris tècnics, econòmics i ambientals. L'algoritme híbrid proposat dissenya programes de conservació amb una efectivitat mitjana un 9% superior a l'obtinguda amb l'algoritme de busca per entorns més eficaços, requerint per a això un menor esforç computacional. En l'aplicació al cas d'estudi xilé, s'observa que l'algoritme híbrid millora la gestió actual, augmentant en un 22% la condició mitjana de la xarxa i reduint, a més, les emissions de CO2 en un 12%. En termes pràctics, els programes òptims consideren una política proactiva, en la que els paviments es tracten quan la condició dels mateixos encara és bona. Finalment, la ferramenta proposada millora la planificació temporal dels recursos. Basant-se en les evidències demostrades en el cas d'estudi, es conclou que la distribució temporal del pressupost és un factor clau en l'exercici tècnic i ambiental de la xarxa.Torres Machí, C. (2015). Optimización heurística multiobjetivo para la gestión de activos de infraestructuras de transporte terrestre [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/48878TESISPremios Extraordinarios de tesis doctorale

Implementation of Earned Value Management in Unit-Price Payment Contracts

[EN] The earned value management (EVM) method is internationally considered a standard tool in the project management field, enabling professionals to plan and control cost and schedule in an integrated manner. However, evidence indicates that EVM is not typically implemented by contractors when the payment agreement is based on unit-prices. In this payment approach, the owner pays the quantities actually executed according to the preagreed rate established in the contract for each unit or task; the income received by the contractor from the owner (generally named production) is neither proportional to costs nor fixed a priori, as in cost-reimbursable and lump sum contracts, respectively. Therefore, contractors have to control not only cost but also production. The current formulation of EVM does not allow controlling production; an additional baseline is needed. In response, this paper presents a proposal for adapting EVM to contractors when using the unit-prices payment agreement. Using a case study to illustrate, an additional baseline to account for production and profitability, as well as new indicators, is applied to allow contractors using EVM with this payment approach; this is the contribution of this paper to the body of knowledge. The proposed EVM formulation provides information not only in terms of cost (as in the traditional EVM approach) but also in terms of production.This research was supported by the Universitat Politècnica de València, which funded a visiting scholarship for Dr. Monty Sutrisna (Action 19701344)Picornell, M.; Pellicer, E.; Torres-Machí, C.; Sutrisna, M. (2017). Implementation of Earned Value Management in Unit-Price Payment Contracts. Journal of Management in Engineering. 33(3):06016001-1-06016001-7. https://doi.org/10.1061/(ASCE)ME.1943-5479.0000500S06016001-106016001-733

Employability of Graduate Students in ConstructionManagement

"This material may be downloaded for personal use only. Any other use requires prior permission of the American Society of Civil Engineers"The economic crisis that currently affects some Western countries has reduced the employability of graduates in the construction industry. Nevertheless, many young professionals consider this situation as an opportunity to further their training, thus the higher enrollment in graduate programs in the construction industry. In light of this scenario, the authors of this paper sought to identify students perceptions of training gaps that affect their employability. The research was based on a case study, conducted in a Spanish graduate program (M.Sc.) in construction management during two consecutive academic years; a questionnaire survey was given to all of the enrolled students at the beginning of the first semester. The statistical analyses consisted of a principal-component analysis of the 21 variables listed as possible explanations for their graduates unemployment and an analysis of variance based on the previously noted principal components. Respondents recognized the intrinsic internal barriers that jeopardized their job opportunities, such as their unwillingness to move to another country, their lack of knowledge of a foreign language and communication skills, or their preferences for only well-paid and comfortable jobs. Other perceived problems were related to economic policy, training gaps, labor market structure, graduate surplus, and setbacks related to business management.Torres Machí, C.; Carrión García, A.; Yepes Piqueras, V.; Eugenio Pellicer (2013). Employability of Graduate Students in ConstructionManagement. Journal of Professional Issues in Engineering Education and Practice. 139(2):163-170. doi:10.1061/(ASCE)EI.1943-5541.0000139S163170139

Integración de investigación y docencia de posgrado a través del diseño eficiente de estructuras

[EN] This paper describes, with a case study, the teaching methodology in which a research perspective is introduced in a master program. Throughout the semester, students are asked to apply and analyze the results obtained with the implementation of different heuristic algorithms for the optimal design of a concrete structure. As a final report, students should implement a heuristic algorithm different to those implemented in class for the optimal design of the concrete structure. The results obtained should be presented in the format of a scientific paper. The case study presented in this paper consists on the optimization of the mix design of simply supported beams made of high-performance concrete (HPC). The optimization algorithm implemented is an hybrid strategy based on a variable neighborhood search and threshold acceptance algorithm. This paper begins by defining the optimization problem. It will then go on to present the results of applying the optimization algorithm. Finally, a parametric study is undertaken, analyzing beams with lengths varying from 10 to 20 m. The application of this teaching methodology has supposed an aditional challenge to postgraduate students, as they not only have to adquire the technical competences of the subject but they also have to apply them in a practical example and publish the results in the format of a scientific journal.[ES] Este artículo presenta, a partir de un caso práctico, la metodología docente empleada en un programa de máster en la que se introducen enfoques propios de la investigación a la formación de los alumnos de posgrado. A lo largo del curso, los alumnos aplican distintos algoritmos de optimización heurística en el diseño de una estructura de hormigón y analizan los resultados obtenidos con cada uno de ellos. Como trabajo final, deben emplear alguna herramienta heurística novedosa para el diseño de la estructura analizada y presentar los resultados obtenidos en formato de artículo científico. El caso presentado consiste en la optimización de vigas biapoyadas de hormigón de alta resistencia a través de una estrategia de optimización híbrida basada en la búsqueda en entornos variables y la aceptación por umbrales. En una primera parte, el artículo plantea el problema de optimización. A continuación se presenta la aplicación del algoritmo propuesto de optimización. Finalmente se realiza un estudio paramétrico para vigas de luces comprendidas entre 10 y 20 m. La aplicación de esta metodología docente ha supuesto un reto adicional para los alumnos de máster, que se enfrentan no sólo a adquirir los conocimientos de la materia sino a aplicarla a un ejemplo práctico y a publicar los resultados obtenidos en revistas científicas.Este proyecto ha sido parcialmente financiado por el Ministerio de Ciencia e Innovación (BIA2011- 23602).Torres-Machí, C.; Yepes, V.; Alcalá, J.; Pellicer, E. (2013). Integración de investigación y docencia de posgrado a través del diseño eficiente de estructuras. Modelling in Science Education and Learning. 6(3):89-100. doi:10.4995/msel.2013.1986SWORD891006

Assessing social performance of construction companies in public-works procurement: Data envelopment analysis based on the benefit of the doubt approach

[EN] There is an urgent need to improve the assessment of construction companies' Corporate Social Responsibility (CSR) in public-works procurement. Current procurement procedures assign a high level of subjectivity to CSR assessment and lack transparency. Existing research basically highlights the need to define weighting systems in which the importance of each social criterion is objective and based on the social weaknesses in the context of a project. In order to fulfill this gap, this research proposes a composite indicator for assessing CSR in public construction procurement. A Data Envelopment Analysis based on the Benefit of Doubt Approach (DEA-BOD) was chosen to define the weighting system based on the main social weaknesses that exist in the country where the contract is procured. The research employs simulation to assess the validity of this indicator. The results highlight that the use of national indices as a proxy for CSR indicators can be helpful in determining the level of importance of CSR in public procurement. The simulation showed that the proposed approach allows the objective comparison of CSR performance of construction companies, regardless of their size. This research assists decision-makers in properly integrating social sustainability in procurement procedures.The authors acknowledge the financial support of the Universitat Politecnica de Valencia (PAID -00-17) . The authors are grateful to the expert panel for their participation in this research.Montalbán-Domingo, L.; García-Segura, T.; Sanz-Benlloch, A.; Pellicer, E.; Torres-Machí, C.; Molenaar, K. (2022). Assessing social performance of construction companies in public-works procurement: Data envelopment analysis based on the benefit of the doubt approach. Environmental Impact Assessment Review. 96:1-15. https://doi.org/10.1016/j.eiar.2022.1068441159

Modelos y prácticas actuales en la evaluación económica y ambiental para la gestión sostenible de redes de pavimentos

[EN] 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.[ES] Las infraestructuras de transporte terrestre y particularmente la infraestructura vial son fundamentales en el desarrollo económico y social. El nivel de calidad percibido por el usuario viene determinado, principalmente, por el pavimento. A nivel mundial se invierte anualmente más de 400 mil millones de dólares en la construcción y el mantenimiento de pavimentos; tareas que aumentan en un 10% el impacto ambiental generado por la circulación de los vehículos. Surge así la necesidad de incorporar un enfoque sostenible en la evaluación de alternativas de conservación que considere aspectos técnicos, económicos, medioambientales, políticos e institucionales de forma integrada y armónica a lo largo de su ciclo de vida. La presente investigación tiene por objeto estudiar los modelos y prácticas en la evaluación económica y ambiental de pavimentos para analizar las ventajas y las limitaciones de la práctica actual e identificar oportunidades para mejorar su gestión sostenible. Una de las principales limitaciones identificadas es la escasez de modelos que consideren de forma integrada los aspectos económicos y ambientales. Se detecta la necesidad de modelos que consideren el efecto sobre los usuarios en zonas de trabajo así como el uso de nuevas tecnologías y materiales reciclados más respetuosos con el medio ambiente.Authors gratefully acknowledge members of the research group at the Pontificia Universidad Católica de Chile for their resources during the study. The research team acknowledges Fondef/Conicyt 2009 for funding the project “Research and Development of Solutions for Urban Pavement Management in Chile” (D09I1018) and the National Research Center for Integrated Natural Disaster Management CONICYT/FONDAP/15110017. Funding over Conicyt (CONICYT-PCHA/Doctorado Nacional/2013-63130138) to support this work is sincerely appreciated..Torres Machí, C.; Chamorro, A.; Yepes, V.; Pellicer Armiñana, E. (2014). Current Models and Practices of Economic and Environmental Evaluation for Sustainable Network-Level Pavement Management. Revista de la Construcción. 13(2):49-56. http://hdl.handle.net/10251/55539S495613

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 onwhen and howto apply availablemethods 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.The authors gratefully acknowledge members of the research group at the Pontificia Universidad Catolica de Chile for their contributions and resources during the study. The research team acknowledges Conicyt-Fondef/Decimoseptimo Concurso de Proyectos de Investigacion y Desarrollo del Fondo de Fomento al Desarrollo Cientifico y Tecnologico, Fondef/Conicyt 2009 (D09I1018) for funding this project. Support of the associated institutions is also appreciated: Ministry of Housing and Urban Development (Ministerio de Vivienda y Urbanismo), Regional Government for Metropolitan Region (Gobierno Regional de la Region Metropolitana), Municipality of Santiago (Municipalidad de Santiago), and Municipality of Macul (Municipalidad de Macul). Funding over Santander Universidades (Becas Iberoamerica Jovenes Profesionales e Investigadores, 2013) to support this work is sincerely appreciated.Torres Machí, C.; Chamorro, A.; Videla, C.; Pellicer Armiñana, E.; Yepes, V. (2014). An Iterative Approach for the Optimization of Pavement Maintenance Management at the Network Level. Scientific World Journal. 2014(4329):1-11. https://doi.org/10.1155/2014/524329S11120144329Qin, J., Ni, L., & Shi, F. (2013). Mixed Transportation Network Design under a Sustainable Development Perspective. The Scientific World Journal, 2013, 1-8. doi:10.1155/2013/549735Chamorro, A., & Tighe, S. L. (2009). 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International Journal of Pavement Engineering, 15(3), 238-250. doi:10.1080/10298436.2012.657798De la Garza, J. M., Akyildiz, S., Bish, D. R., & Krueger, D. A. (2011). Network-level optimization of pavement maintenance renewal strategies. Advanced Engineering Informatics, 25(4), 699-712. doi:10.1016/j.aei.2011.08.002Gao, L., Xie, C., Zhang, Z., & Waller, S. T. (2011). Network-Level Road Pavement Maintenance and Rehabilitation Scheduling for Optimal Performance Improvement and Budget Utilization. Computer-Aided Civil and Infrastructure Engineering, 27(4), 278-287. doi:10.1111/j.1467-8667.2011.00733.xAmador-Jiménez, L. E., & Mrawira, D. (2009). Roads Performance Modeling and Management System from Two Condition Data Points: Case Study of Costa Rica. Journal of Transportation Engineering, 135(12), 999-1007. doi:10.1061/(asce)te.1943-5436.0000074Gao, L., & Zhang, Z. (2008). Robust Optimization for Managing Pavement Maintenance and Rehabilitation. Transportation Research Record: Journal of the Transportation Research Board, 2084(1), 55-61. doi:10.3141/2084-07Ng, M., Zhang, Z., & Travis Waller, S. (2011). The price of uncertainty in pavement infrastructure management planning: An integer programming approach. Transportation Research Part C: Emerging Technologies, 19(6), 1326-1338. doi:10.1016/j.trc.2011.03.003Ferreira, A., Antunes, A., & Picado-Santos, L. (2002). Probabilistic Segment-linked Pavement Management Optimization Model. Journal of Transportation Engineering, 128(6), 568-577. doi:10.1061/(asce)0733-947x(2002)128:6(568)Yoo, J., & Garcia-Diaz, A. (2008). Cost-effective selection and multi-period scheduling of pavement maintenance and rehabilitation strategies. Engineering Optimization, 40(3), 205-222. doi:10.1080/03052150701686937Farhan, J., & Fwa, T. F. (2012). Incorporating Priority Preferences into Pavement Maintenance Programming. Journal of Transportation Engineering, 138(6), 714-722. doi:10.1061/(asce)te.1943-5436.0000372Fwa, T. F., & Farhan, J. (2012). Optimal Multiasset Maintenance Budget Allocation in Highway Asset Management. Journal of Transportation Engineering, 138(10), 1179-1187. doi:10.1061/(asce)te.1943-5436.0000414Tsunokawa, K., Van Hiep, D., & Ul-Islam, R. (2006). True Optimization of Pavement Maintenance Options with What-If Models. Computer-Aided Civil and Infrastructure Engineering, 21(3), 193-204. doi:10.1111/j.1467-8667.2006.00427.xChou, J.-S., & Le, T.-S. (2011). Reliability-based performance simulation for optimized pavement maintenance. Reliability Engineering & System Safety, 96(10), 1402-1410. doi:10.1016/j.ress.2011.05.005Flintsch, G. W., & Chen, C. (2004). Soft Computing Applications in Infrastructure Management. Journal of Infrastructure Systems, 10(4), 157-166. doi:10.1061/(asce)1076-0342(2004)10:4(157)Chan, W. T., Fwa, T. F., & Tan, J. Y. (2003). Optimal Fund-Allocation Analysis for Multidistrict Highway Agencies. Journal of Infrastructure Systems, 9(4), 167-175. doi:10.1061/(asce)1076-0342(2003)9:4(167)Chootinan, P., Chen, A., Horrocks, M. R., & Bolling, D. (2006). A multi-year pavement maintenance program using a stochastic simulation-based genetic algorithm approach. Transportation Research Part A: Policy and Practice, 40(9), 725-743. doi:10.1016/j.tra.2005.12.003Meneses, S., & Ferreira, A. (2013). Pavement maintenance programming considering two objectives: maintenance costs and user costs. International Journal of Pavement Engineering, 14(2), 206-221. doi:10.1080/10298436.2012.727994Fwa, T. F., & Chan, W. T. (1993). Priority Rating of Highway Maintenance Needs by Neural Networks. Journal of Transportation Engineering, 119(3), 419-432. doi:10.1061/(asce)0733-947x(1993)119:3(419)Moazami, D., Behbahani, H., & Muniandy, R. (2011). Pavement rehabilitation and maintenance prioritization of urban roads using fuzzy logic. Expert Systems with Applications, 38(10), 12869-12879. doi:10.1016/j.eswa.2011.04.079Khurshid, M. B., Irfan, M., Ahmed, A., & Labi, S. (2013). Multidimensional benefit–cost evaluation of asphaltic concrete overlays of rigid pavements. Structure and Infrastructure Engineering, 10(6), 792-810. doi:10.1080/15732479.2013.767842Khurshid, M. B., Irfan, M., & Labi, S. (2009). Comparison of Methods for Evaluating Pavement Interventions. Transportation Research Record: Journal of the Transportation Research Board, 2108(1), 25-36. doi:10.3141/2108-03Kirkpatrick, S., Gelatt, C. D., & Vecchi, M. P. (1983). Optimization by Simulated Annealing. Science, 220(4598), 671-680. doi:10.1126/science.220.4598.671Martí, J. V., Gonzalez-Vidosa, F., Yepes, V., & Alcalá, J. (2013). Design of prestressed concrete precast road bridges with hybrid simulated annealing. Engineering Structures, 48, 342-352. doi:10.1016/j.engstruct.2012.09.01

Impact of the Economic Crisis in Construction: A Perspective from Graduate Students

[EN] The current economic crisis has affected the Spanish construction industry causing the loss of 1.2 million jobs in the last four years. This paper seeks to analyze the impact of this crisis in construction from the point of view of the students of a M.Sc. in Construction Management, investigating the evolution of student's perception on unemployment and their motivations to enroll in the master degree. For this purpose, a questionnaire was handed out to students of three consecutive classes of the M.Sc. in Construction Management at the Universitat Politècnica de València (Spain). A statistical analysis of the survey was developed. This way, some interesting points can be highlighted on the impact of crisis on young construction professionals.The authors are grateful to the students of the Master of Planning and Management in Civil Engineering for their cooperation, as well as the Universitat Politècnica de València through the Education Improvement and Innovation Project PIME 2012 (EXCELCON group).Torres Machí, C.; Pellicer, E.; Yepes Piqueras, V.; Picornell Tronch, M. (2013). Impact of the Economic Crisis in Construction: A Perspective from Graduate Students. Procedia Social and Behavioral Sciences. 89:640-645. doi:10.1016/j.sbspro.2013.08.908S6406458

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

Sustainability, which is founded in 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 400 billion USD are invested globally each year in pavement construction and maintenance. These tasks increase the environmental impacts of vehicle operation by 10%. Because maintenance should be technically appropriate, it is important to integrate technical, economic and environmental aspects in the evaluation of maintenance alternatives over the life cycle of pavement. However, these aspects are normally assessed in different units that are difficult to combine in the decision-making process. This research examines and compares different methods for the integrated consideration of technical, economic and environmental aspects. This study aims to assist highway agencies, researchers and practitioners with the integration of these aspects for the sustainable management of pavement. For this purpose, a set of maintenance alternatives for asphalt pavements are evaluated. Different methods for the integration of these aspects are explored, leading to recommendations for the most suitable methods for different scenarios. Because of this analysis, the Analytic Hierarchy Process (AHP) is recommended when the number of alternatives is reduced. In these situations, the AHP leads to results that are similar to those of the Weighting Sum and Multi-Attribute approaches that are frequently used for intuitive selection. However, when the number of alternatives is large, pair comparison becomes difficult when using the AHP and the Weighting Sum method becomes more appropriate.The authors gratefully acknowledge the scholarship awarded by the Vicerrectoria de Investigacion from the Pontificia Universidad Catolica de Chile and funded by the Ministerio de Educacion de Chile. The research team acknowledges FONDEF-Comision Nacional de Investigacion Cientifica y Technologica (CONICYT) 2009 for funding the project Research and Development of Solutions for Urban Pavement Management in Chile. In addition, the authors sincerely appreciate the funding provided by CONICYT and the National Research Center for Integrated Natural Disaster Management.Torres Machí, C.; Chamorro, A.; Pellicer Armiñana, E.; Yepes, V.; Videla, C. (2015). Sustainable Pavement Management. Integrating Economic, Technical, and Environmental Aspects in Decision Making. Transportation Research Record. 2523:56-63. doi:10.3141/2523-07S56632523Chester, M. V., & Horvath, A. (2009). Environmental assessment of passenger transportation should include infrastructure and supply chains. Environmental Research Letters, 4(2), 024008. doi:10.1088/1748-9326/4/2/024008Chamorro, A., & Tighe, S. L. (2009). Development of a Management Framework for Rural Roads in Developing Countries. Transportation Research Record: Journal of the Transportation Research Board, 2093(1), 99-107. doi:10.3141/2093-12Torres-Machi, C., Chamorro, A., Yepes, V., & Pellicer, E. (2014). Current models and practices of economic and environmental evaluation for sustainable network-level pavement management. Revista de la construcción, 13(2), 49-56. doi:10.4067/s0718-915x2014000200006Haas, R., Tighe, S. L., & Falls, L. C. (2006). Determining Return on Long-Life Pavement Investments. Transportation Research Record: Journal of the Transportation Research Board, 1974(1), 10-17. doi:10.1177/0361198106197400102Wu, Z., Flintsch, G., Ferreira, A., & Picado-Santos, L. de. (2012). Framework for Multiobjective Optimization of Physical Highway Assets Investments. Journal of Transportation Engineering, 138(12), 1411-1421. doi:10.1061/(asce)te.1943-5436.0000458Wu, Z., & Flintsch, G. W. (2009). Pavement Preservation Optimization Considering Multiple Objectives and Budget Variability. Journal of Transportation Engineering, 135(5), 305-315. doi:10.1061/(asce)te.1943-5436.0000006Cafiso, S., Di Graziano, A., Kerali, H. R., & Odoki, J. B. (2002). Multicriteria Analysis Method for Pavement Maintenance Management. Transportation Research Record: Journal of the Transportation Research Board, 1816(1), 73-84. doi:10.3141/1816-09Giustozzi, F., Crispino, M., & Flintsch, G. (2012). Multi-attribute life cycle assessment of preventive maintenance treatments on road pavements for achieving environmental sustainability. The International Journal of Life Cycle Assessment, 17(4), 409-419. doi:10.1007/s11367-011-0375-6Nathman, R., McNeil, S., & Van Dam, T. J. (2009). Integrating Environmental Perspectives into Pavement Management. Transportation Research Record: Journal of the Transportation Research Board, 2093(1), 40-49. doi:10.3141/2093-05Robinette, C., & Epps, J. (2010). Energy, Emissions, Material Conservation, and Prices Associated with Construction, Rehabilitation, and Material Alternatives for Flexible Pavement. Transportation Research Record: Journal of the Transportation Research Board, 2179(1), 10-22. doi:10.3141/2179-02Osorio, A., Chamorro, A., Tighe, S., & Videla, C. (2014). Calibration and Validation of Condition Indicator for Managing Urban Pavement Networks. Transportation Research Record: Journal of the Transportation Research Board, 2455(1), 28-36. doi:10.3141/2455-04Saaty, T. L. (1990). How to make a decision: The analytic hierarchy process. European Journal of Operational Research, 48(1), 9-26. doi:10.1016/0377-2217(90)90057-