The use of public private partnerships (PPPs) for investment in transport infrastructure has a long history, spreading rapidly in Latin America in the 1980s and in the 1990s in the UK. There are many forms of PPP, ranging from the project finance type (e.g. Design, Build, Finance, Maintain, Operate (DBFMO) contracts) to concessions with economic regulation, with the line between partnership and outright privatisation somewhat blurred. PPPs sought to bring efficiency incentives from private sector management into network industries (power transmission, water supply, road and rail infrastructure provision) that bear the hallmarks of natural monopoly and were traditionally managed by the state in many places.