Economic growth, social wellbeing, and infrastructure are strongly interrelated and jointly contribute to national development. Therefore, evaluation and selection of a road infrastructure project direly need a comprehensive sustainability assessment integrating holistic decision criteria. This study presents an elaborate life cycle sustainability-based project evaluation tool, comprising an assessment framework, an integration model, and a decision framework. In the first phase, a life cycle sustainability assessment (LCSA) framework for road infrastructure is established using mixed methods. In the second phase, interviews are conducted to obtain pairwise comparisons among impact categories and subjective reasoning of their priorities. Analytical hierarchy process (AHP) is adopted to develop the LCSA integration model. The minimum threshold limits of impact categories are evaluated and integrated into the proposed decision framework. Further, thematic and cross-sectional analyses are performed on the interview findings to rationalize the proposed decision framework. The findings include a detailed and customized project assessment framework, an integration model, and a decision framework for the assessment of different project alternatives. This study helps policy- and decision-makers in selecting the project alternative by maximizing sustainability in road infrastructure projects. Insights into environmental and social externalities and their quantitative interpretation throughout the life of the road are also achieved.

Abstract:The construction industry consumes a large part of raw material and global energy, and produces huge amount of solid waste. It is established that waste generated by construction processes has significant negative impact on the economy and environment. Effective waste management helps in reducing quantity of wastes and making a substantial contribution towards sustainable development and cost control. Based on a benchmarking approach, this research quantifies the material wastage and its causes in different types of building projects. In a waste diagnostic survey, 38 project sites were surveyed. Results revealed that bricks, tiles, and plaster from mortar are the most wasteful materials, and improper worker's skills, poor supervision, and lack of management the most significant causes. Buildings with substantial architectural works tend to generate maximum amount of waste while contractor size does not affect waste generation rate. Based on expert opinion, practical recommendations are given to control material waste. The findings offer a new perspective on sustainable construction by correlating building types with waste generation, as contribution to the existing body of knowledge. It will lead the construction managers to better understand the actual situation of construction waste and devise control measures.

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PurposeThe construction industry struggles in environmental and economic performance due to waste generation. Several studies have measured this waste in the construction industry of developing countries like India, Brazil, China, Nigeria and Iran, and proposed strategies to enhance the overall efficiency. But no such work exists in Pakistan's context. The construction industry of Pakistan contributes significantly to the country's gross domestic product (GDP). And with several mega projects in progress to overcome the energy crises and improve the infrastructure of the country, the absence of proper waste management policies and plans calls for empirical research. Therefore, this study quantifies and benchmarks material waste in the local context, its impact on project cost and the effect of multiple subcontracting arrangements on waste generation. It also proposes a conceptual waste management plan (WMP) for local conditions which can be generalized for developing countries.Design/methodology/approachThis paper uses a mixed research approach by leveraging Saunders's research onion model. To benchmark the current wastage practices, quantitative data of material waste in the Pakistani construction industry are gathered through document review of accounting systems, inventory and payment records of 40 completed building projects. Using the data, the waste rate of different materials is measured along with their impact on cost. Additionally, the role of subcontracting arrangements in waste generation is also investigated. Also, semi-structured interviews are conducted with project managers of high- and low-performing construction organizations to propose a conceptual WMP for the local industry and developing countries.FindingsThe highest wasteful materials by quantity are wood, sand and concrete blocks, and those by cost are wood, bricks and steel. By quantity, 123% more material was used on average than the actual productive work. Also, the labor only (L-O) subcontracting arrangement causes maximum waste. Moreover, the difference between the highest (155%) and lowest wasting company (104%) is 51%, highlighting the proactive and resistive waste management culture and approach by the worst- and best-performing companies. Further, the impact of waste quantities is more than 2% of the project cost. Finally, a conceptual model consisting of measures at the project, industry and national levels is also proposed as a guide for developing countries.Practical implicationsThe findings of this benchmarking study can help improve the project planning, execution and monitoring, and control practices by providing a better understanding of the material waste potential. This will help economize the construction industry and improve its sustainability.Originality/valueThis is the first benchmarking study that quantitatively measures material waste in the construction industry of Pakistan. It highlights that costly as well as sustainability-implicating materials are frequently wasted in the local construction projects. Also, this study correlates the wastage with subcontracting arrangements. Additionally, an original conceptual WMP is proposed that could help the industry improve its performance. The findings could help the construction professionals identify the loopholes in their material management practices and not only save money but also ensure better sustainability.