Summary. Falls from height are one of the leading causes of death in the construction industry. The recent advancement and deployment of various sensing and mobile computing technologies on construction sites has provided an opportunity to implement an autonomous safety monitoring system to prevent falls from height and thereby improve performance industry safety. This paper presents the preliminary result of the first stage of research on our envisioned autonomous security monitoring system. In the article, the authors defined the dynamic safe work zone model and the determination of its parameters. The safety knowledge presented in this document can serve as a basis for actual system design and implementation.1 Introduction Although the accident rate in the construction industry has decreased, falls from height account for consistently one of the highest numbers of fatalities in our industry. Among all the causes contributing to falls from height, work surface and platform, worker behaviors and attitudes, structure and construction facilities are the three most cited causes in the literature (Hu etl, 2009). Work at height in the construction industry typically takes place in a dynamic and complex environment and workers are not always aware or have an appropriate assessment of the surrounding risks. To maximize worker awareness of risks, existing practices include installing warning signs/barriers and using supervisors/co-workers to warn a worker if they see them exposed to fall hazards. Recent advancements in sensing and pervasive computing technologies have been introduced into the construction industry for materials management to improve productivity and reduce material wastage (Caldas 2006, Pradhan 2009). The inf...... middle of article ...... focuses on the implementation and validation of the proactive fall prevention system. Works Cited Hu, K., H. Rahmandad, T. Smith-Jackson and WW Winchester (2009). Factors influencing the risk of falls: a review of the evidence in construction. Under review at Construction Management and EconomicsC.H. Caldas, D. Grau, CT Haas, Using the Global Positioning System to Improve Material Locating Processes on Industrial Projects, Journal of Construction Engineering and Management, 132 (2006) 741-749A. Pradhan, E. Ergen, B. Akinci, Technology evaluation of radio frequency identification technology for indoor localization, Journal of Computing in Civil Engineering, 23 (2009) 230-238.OSHA. Safety and health regulations for construction. Subpart M: Fall Protection. (1926).OSHA. Occupational safety and health standards. Subpart O: Machinery and machine protection (1910).