System engineering in London Underground

London Underground (LU) has been formally applying system engineering techniques on major projects since the early 1990s and more generally for the last five years. Much has been learned from its experiences to date and has been enshrined within its current approaches and standards. This paper gives an overview of how system engineering is viewed within London Underground, particularly now that the majority of LU projects are being executed under 30 year public private partnership contracts (PPPs). Some discussion of the nature and challenges of system engineering in a major heavy metro is given. London Underground's approach relies on the incentives provided by the PPP along with high level system standards covering the system engineering process, human factors integration, and electromagnetic compatibility.