This document summarizes barriers to public-private partnerships (PPPs) in infrastructure projects based on a literature review. It identifies 8 main categories of barriers: legal, regulatory environment, financial problems, political risk, technological, decentralization, policy/institutional, and resistance to change. Under each category, it lists specific barriers identified in other research papers and publications, along with the authors and years of those sources. It then provides an overview of Interpretive Structural Modeling (ISM), which is a methodology used to better understand complex systems by identifying relationships and structure between different elements. The document aims to categorize and analyze barriers to PPPs based on previous research in order to better understand challenges to these types of partnerships