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.

Accurate and timely identification and tracking of construction components are critical to operating a well-managed and cost efficient construction project. Establishing standards to support identification and tracking technologies has the potential to enable the construction industry to seamlessly integrate work processes at the job-site. This paper discusses on-going research at NIST in the application of field sensors, portable computers, real-tune high-precision global positioning, wireless communications, and construction project databases, to develop means for real-time component identification and tracking.

Abstract-Digital inclinometers are used in geotechnical engineering to monitor lateral deformations of excavation walls, retaining walls, embankments and landslide areas. Current conventional slope inclination measurement requires a person to manually lower a probe into a grooved casing and record inclination at prescribed intervals as the probe is drawn upwards. Developing an automated inclinometer system would enable continuous monitoring for use in intelligent construction as well as provide significant savings in terms of equipment, material and labor costs. This paper investigates the use of lowcost wireless sensor nodes as an alternative to traditional inclinometer systems used in geotechnical engineering applications.

Tests of a novel concept for tracking construction components were carried out at the National Institute of Standards and Technology. The approach makes use of laser radar and retro-reflective barcodes attached to manufactured building materials. Tests were conducted for various barcode sizes and spacings through a variety of ranges to a maximum of 40 m. At 40 m, it was possible to infer one byte of information content in a 1D barcode measuring 575 mm (22.6 in.) in length with no special optical processing for a LADAR instrument with an aperture beam diameter of 25 mm and a beam divergence of 2.7 mrad. Simple thresholding post-processing techniques were employed to study the resulting intensity data and to deduce minimum detectable bar gap spacing. These analyses have suggested paths to significant resolution enhancements based on image processing and optical physics simulation techniques.