Determining what physical activity the user is performing using mobile devices is an elusive task even though consumer off the shelf (COTS) mobile devices carried by most users contain a vast array of physical sensors. When conducting work improvement studies, construction crew members are typically observed by eye to record information about the physical activities being performed. Another approach to capturing crew member activities is utilizing sensors within COTS mobile devices carried by crew members. This paper presents CTrack: an approach for capturing telemetry from the array of sensors on-board COTS mobile devices. The resulting sensor telemetry is fused together and can be used to make informed decisions when characterizing crew member activities. Additionally, this paper presents results from field testing CTrack and discusses the current benefits and limitations of fusing multiple telemetry sources to characterize crew member activities.