This "Traffic Control Systems Handbook" updates the 1985 edition (FHWA-IP-85-11; TRIS 00475445) and broadens the scope to include Intelligent Transportation Systems (ITS) technology and concepts. The Handbook recommends decision-making processes in selection, implementation and operations of a traffic control system and describes ITS plans and programs. The "Traffic Control Systems Handbook": serves as a basic reference in planning, designing and implementing effective traffic control systems; provides an updated compendium of existing traffic control technology for the advanced designer and user; describes existing and evolving traffic control system technology; and aids understanding and facilitates training in the traffic control system field. The Handbook targets: administrators; traffic engineers; transportation planners; and students. In addition to summarizing the state-of-the-practice, chapters include "A Look to the Future" section where appropriate. In this way, the material separates proven technology from systems and elements currently under development.