This paper presents further development and experimental testing of Comp-TRAK, a prototype system for identification and spatial tracking of structural steel components on a live construction site. Comp-TRAK is a web-based system for rapid tracking of construction components with compact, field-rugged sensors and computers, interoperability protocols for data transmission, and a 3-D site visualizer that reflect the current state of tracked components on the construction site. The result is a graphicallydriven system that provides real-time identification, position, and orientation data about components to users in the field and at remote locations.