The term Public Private Partnerships includes different forms of collaboration between the public and the private sector. These formulas are adopted in a constantly increasing number of countries all over the world in order to overcome the chronic lack of funding and ensure the delivery of infrastructure projects. The paper illustrates the vital role of cooperation between public bodies and private entities in the delivery of public transportation infrastructure. In particular, it focuses on toll roads and highways. Key factors of success and risk are identified and illustrated through five case studies from Chile, Hungary, South Africa-Mozambique, United Kingdom and California.