Systems engineering is a structured, interdisciplinary development process for planning, designing, implementing, managing, operating, and retiring a system. This approach, as outlined in the Federal Highway Administration's Systems Engineering Guidebook for ITS, emphasizes defining customer needs and required functionality early in the development cycle, before moving on to design, build, and deploy the system. The purpose is to plan for the entire life cycle of a project up-front, to minimize the risk to budget, scope, and schedule.
As a comprehensive planning approach, systems engineering relies heavily on traceability and documentation, as well as on the use of "decision gates" to determine when to pass from one step in the process to the next. Its overall trajectory is often represented by the "V" diagram:
The left side of the diagram focuses on the definition and decomposition of the system to be built, the base on the building of the system components, and the right side on the integration and testing of system components, as well as acceptance and operation of the system. There are significant interactions between the two sides of the diagram: verification and validation plans developed during the decomposition of the system on the left side of the process are used on the right side to make sure the resulting components and integrated system meet the needs and requirements of the stakeholders. Throughout the process, “decision gates” are used as decision points to determine if a particular step has been completed to the satisfaction of the initially established criteria.