An Integrated Sustainability Assessment Framework for Public–Private Partnerships in Highway Projects

Abstract

Public–private partnerships (PPPs) and sustainability have received considerable attention in delivery and execution of transportation infrastructure projects in the United States. Existing sustainability rating tools are neither designed nor suitable for PPPs due to unbalanced weights among the triple bottom line (TBL) of sustainability and the lack of additional considerations beyond the TBL. This study proposes and validates an integrated sustainability assessment framework that aims to capture all of the relevant and important decision factors in terms of assessing the sustainability of PPP highway projects in a comprehensive manner. Through literature review, semistructured interviews, and questionnaire surveys featuring Delphi and analytic hierarchy process techniques, a list of applicable assessment factors (five dimensions, 18 indicators, and 65 subindicators) and their respective weights and priorities were identified. Based on these assessment factors, the proposed framework seeks to determine PPP projects’ level of achievement in terms of sustainable practices. The framework was validated for its applicability and usability for US PPP highway projects through an online survey. Results show that the economic/financial dimension is the most important dimension for highway PPP experts, followed by contractual, technical, environmental, and social dimensions in descending order by relative importance. This calls for additional attention to be paid to environmental and social sustainability considerations in PPP highway projects. Meanwhile, the results also reflect an urgent need for improved sustainability planning and awareness among stakeholders of PPP highway projects.