Date of Award


Document Type


Degree Name

Master of Science (MS)


Systems Engineering

First Advisor

Smith-Jackson, Dr. Tonya L.


Falls from roofs are a serious problem in construction sectors. A significant number of workers experience fatal falls from residential structures while performing roofing tasks each year. According to a relatively new OSHA ruling for residential construction, fall protection equipment is mandatory when working at heights of six feet or more. However, lack of ease in using equipment, workers' attitude towards safety equipment and sometimes discomfort in usage of the equipment create obstacles in facilitating the use of fall protection equipment. The difficulty in adopting fall protection equipment has been studied by using scaled models to simulate the actual work environment. In this research, a comparative study was performed between indoor and outdoor scaled models to explore the ecological validity of the indoor scaled model by using the outdoor model as representative of a higher fidelity residential roofing context. The work procedures and task setups were kept similar between both contexts and subjects' behaviors were observed closely. Data were collected by questionnaire and observation techniques. The data were analyzed to examine the differences in both contexts. The primary hypotheses were focused on the presence or absence of differences between the indoor and outdoor models in terms of performance time, critical incidents and usability ratings. Fidelity of the scaled models was investigated based on the participants' perceptions. Mixed results were found. Findings supported the fidelity of the outdoor scaled model as a sufficient replication of the real world. The outdoor scaled model was perceived to be more similar to the actual construction site than the indoor scaled model. Guidelines about the applicability of the indoor and outdoor scaled models were provided based on the findings of this study.