Academics have been devoting a growing attention to different matters involving public-private partnerships (PPPs), and, as the use of PPPs for delivering infrastructure evolves worldwide, so does the number and type of papers addressing this procurement model. The objective of this paper is to undertake a comprehensive literature review of papers relating to PPPs and private finance initiatives (PFIs), using a bibliometric analysis. More than 600 papers published between 1990 and 2014 were examined. None of the previously existing studies analyzed such a large sample of papers. The research found that PPP studies appear to have a steady momentum toward growth. Engineering journals (and engineering as a research area) have been particularly active in this field. Authors based in Europe and Asia had written almost two-thirds of the papers, with transportation and health sectors at the top of sector-based papers. Most of the existing work is focused on aspects of contract design, risk sharing, and a...

Currently, the world is facing resource scarcity as the environmental impacts of human intervention continue to intensify. To facilitate the conservation and recovery of ecosystems and to transform cities into more sustainable, intelligent, regenerative, and resilient environments, the concepts of circularity and nature-based solutions (NbS) are applied. The role of NbS within green infrastructure in urban resilience is recognised, and considerable efforts are being made by the European Commission (EC) to achieve the European sustainability goals. However, it is not fully evidenced, in an integrated way, which are the main NbS implemented in the urban environment and their effects. This article aims to identify the main and most recent NbS applied in urban environments at the European level and to analyse the integration of different measures as an innovative analysis based on real cases. For this purpose, this work presents a literature review of 69 projects implemented in 24 European cities, as well as 8 urban actions and 3 spatial scales of implementation at the district level. Therefore, there is great potential for NbS adoption in buildings and their surroundings, which are still not prioritized, given the lack of effective monitoring of the effects of NbS.