**7. Conclusions and Future Work**

This comprehensive research study has provided empirically grounded insights from the 40 senior leaders on their perceptions of how their organisations rated and used SDGs as a measurement lens. The 10 findings have provided a rich and deep insight into answering the question of how to measure SDG performance on infrastructure projects. The empirical research has also validated the theory-driven propositions that were synthesised from the literature. Furthermore, this research study identifies that, whilst SDG measurement practices on infrastructure projects are embraced in theory, they are problematic in practice: rarely does action match rhetoric.

Although the 40 interviews described in the study specifically identified a primary stakeholder group, the senior executives of construction firms, there were a number of other stakeholders included, viz. two senior government experts in the infrastructure sector, one financial advisor, one from the United Nations and three from standards bodies. Consequently, the study seeks to include the considerations of wider stakeholders involved in project decision-making. The research team have also consulted with the UK's Institution of Civil Engineers to ensure this broader perspective is adequately captured.

There is evidence that, although the study was completed in the UK, the results may be applicable to a wider international group because most of the firms have extensive global footprints. It is therefore considered that the inherent global nature of SDGs and the global footprint of the organisations interviewed results in the broader international value of this research. The specific benefit to researchers is that the findings extend knowledge on the theory of measuring outcomes and impact at project level, and, for practitioners, the study provides insights into the contextual preconditions necessary to achieve the intended outcomes of adopting a mechanism for the measurement of SDGs. In this way, the article offers learning that has significant implications for investment decisions, where being able to systematically identify SDG impacts, from the start, is helpful for achieving local impact against global targets, with broader benefit for people, profit and the planet. The broader SDG research programme that this paper is part of has worked closely with many international organisations, such as UNOPS, which also signifies that this is an area that has wide relevance and can be added to the growing literature across the world on how we are addressing the grand challenges of the SDGs.

One of the primary characteristics of this qualitative research is that the researcher "is the primary instrument for data collection and data analysis" [49]. However, there is a paradox that, despite this strength, it is also a potential weakness since, unlike a survey or scientific experiment, this allows the "human instrument" to adjust to evolving changes. For example, the lead researcher allowed the interview questions to evolve in a free-flowing discussion when he noted that a different line of enquiry might provide unexpected new insights. There is thus a need to apply some caution to the potential hazard of bringing the researchers' own bias [49], since "it is important to identify them [bias and subjectivity] and monitor them as to how they may be shaping the collection and interpretation of data" (p.13). Another limitation of this study was the research approach. Further research could be expanded to include case studies that test the relevant SDG mechanisms to assess whether the outcomes can be achieved.

In regard to future research, there was a lack of evidence given by participants on their ability to achieve the golden thread of SDG measurement from project to portfolio level (Finding #10) because, often, it was not available at any credible depth or backed up by verifiable evidence. It is therefore proposed that this is an area for further research to test whether aspirations to achieve this linkage are realistic. There is also the need for further research outside the UK since, while the findings from this study have broad global application due to the regional and global footprint of the participants' organisations, the complexities and challenges in some areas require further SDG measurement research.

**Author Contributions:** The research was developed by several authors as follows: Conceptualization, P.M.; methodology, P.M.; validation, P.M., S.P.P. and E.K.; formal analysis, P.M.; investigation, P.M.; data curation, P.M.; writing—original draft preparation, P.M.; writing—review and editing, P.M., S.P.P. and E.K.; visualization, P.M.; supervision, S.P.P. and E.K.; project administration, P.M. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was indirectly funded by the Nathu Puri Institute for Engineering and Enterprise, School of Engineering, London South Bank University, through the funding of the doctoral research support to Paul Mansell.

**Acknowledgments:** The authors would like to thank the Institution of Civil Engineers (ICE) for their advice and support through this phase of research.

**Conflicts of Interest:** The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript or in the decision to publish the results.
