Road infrastructure projects are essential for a country’s economic and social development. Due to the magnitude, the projects are associated with considerable economic investments that in the case of failure can seriously affect regions’ economies. Despite the importance, roads from different countries are affected by cost overruns, hence, it is essential to identify and analyze the causative factors to focus the search for mitigation solutions. There are several studies focused on the cost factors identification, however, studies are lacking that synthesize and analyze the frequency and importance with which the factors have been reported to obtain a phenomenon overview. Therefore, this paper focuses on analyzing the frequency and importance with which cost overrun factors are reported in road projects. The research method consisted of a systematic review compound of five principal stages: (1) question formulation; (2) searching of relevant documents; (3) document selection; (4) evidence collection, analysis and synthesis; and (5) results’ report. Thirty-eight cost overrun factors were identified and classified into 14 categories. According to the Influence Index, the five most important and frequent cost overrun factors were: (1) failures in design, (2) price variation of materials, (3) inadequate project planning, (4) project scope changes, and (5) design changes.

Project delays adversely affect road infrastructure development in developing countries. Unfavorable consequences of project delays involve cost overrun, contractual disputes, arbitration, and quality non-conformities. Despite these risks, literature shows that delays are still a prevalent problem in construction management. Although there is a considerable number of publications on project delays, few studies have compared their causes between developing countries. Therefore, this study aimed to: a) classify and determine the level of influence of the delay causes; b) find the relationship between delay causes and country's development; and c) propose recommendations for mitigating the most critical causes in developing countries. A systematic literature review provided a sample of 14 primary studies from Africa (50%) and Asia (50%). Based on this sample, the study found that developing countries, with a GDP per capita ($US2018) <= $ 2,000, may experience different delay causes depending on the economic and the geographical contexts. In African countries with a Global Competitiveness Index-GCI <= 56, road projects may experience delays due to financial issues of the project owner, as well as delays due to equipment/material issues of the project supplier/subcontractor. On the other hand, in Asian countries with a GCI between 62 and 49, road projects may experience delays due to financial issues of the project contractor, and delays due to planning issues of the project designer/consultant. According to these economic contexts, this study proposes a frame of causes and mitigation actions as a contribution to the risk analysis of road projects in developing countries.

ResumenLa industria de la construcción es una parte importante del aparato económico de un país, por tanto, la verificación de los nuevos sistemas de gestión que se implementan en las principales industrias constructoras del mundo y en donde se obtienen excelentes resultados, merece especial atención.En el presente artículo se hace una revisión bibliográfica de la filosofía Lean Construction (LC) o "construcción sin pérdidas", un nuevo enfoque en la gestión de proyectos de construcción introducido por el profesor Lauri Koskela en el año 1992 basándose en el modelo empleado por la industria automovilística en los 80, la "producción Lean". Koskela propone que la construcción es un sistema de producción que se funda en proyectos con gran incertidumbre en la planificación y una mala concepción de la producción, que es vista como un modelo de transformación solamente. Las bases teóricas de LC propuestas por Koskela pretenden ver la producción en la construcción como un proceso de transformación, de flujo y generador de valor, en consecuencia, el objetivo de Lean Construction es crear buenos sistemas de producción que permitan optimizar, reducir o eliminar los flujos para mejorar los tiempos de entrega. En este sentido, LC es un nuevo pensamiento en gestión de proyectos de construcción que desafía a la guía de gestión actual del Project Management Institute PMBOK, con un alto auge en los Estados Unidos, De ahí que LC no deba ser concebido como un modelo o sistema en el cual solo se siguen unos pasos, sino como un pensamiento dirigido a la creación de herramientas que generen valor a las actividades, fases y etapas de los proyectos de construcción. Entendiendo el valor como la eliminación de todo aquello que produzca perdidas en la ejecución de las mismas.En la fase de construcción por ejemplo, la reducción de los tiempos de ejecución en las actividades de obra, el control del desperdicio de los materiales y la prevención de accidentes laborales son objetivos que si se logran cumplir agregaran valor a tal fase. Basados en estos principios teóricos los investigadores Glenn Ballard y Greg Howell idearon una herramienta denominada Last Planner o como se conoce actualmente en Latinoamérica Sistema del Ultimo Planificador con el objetivo de mejorar el proceso de programación de obra proponiendo la renovación del concepto de planificación de obra tradicional, en donde las actividades que serán hechas se desarrollan sin saber realmente si

An efficient highway infrastructure network is a determining factor in promoting the socio-economic development of countries and regions. Highway planning activities are highly important because their results ensure that projects are delivered within budget, schedule, and scope. Therefore, academics and professionals have promoted various methodological and technological advances focused on improving highway planning processes, evidenced by many scientific documents that address the topic. Despite progress, few studies have focused on analyzing the state of the knowledge structure and the technological and methodological trends of the highway planning topic. Considering this gap, this study presents trends in highway planning and its knowledge structure based on a bibliometric analysis from January 2015 to September 2021. The research method is based on a bibliometric analysis composed of five main stages: (1) scope definition, (2) selection of bibliometric analysis techniques, (3) data collection, (4) bibliometric analysis execution, and (5) evidence analysis and synthesis. Information from 1703 journal papers was collected and analyzed. The findings show that the main trends of highway planning focus on life cycle analysis, computational tools, smart cities, sustainability issues, construction processes, new equipment and materials, and multi-objective optimization, among others. Thus, the findings of this study allow the reader to identify the methodological and technological trends in highway planning and their knowledge gaps to guide future studies in the field.

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