Potential Applications of Unmanned Aerial Systems for Construction Management Tasks
Unmanned Aerial System (UAS), commonly known as drones, have been recently featured in the mainstream media for not so positive reasons. However, we argue that the many positive uses, including in the construction industry, can outweigh the negative ones. These aerial vehicles do not carry a pilot, can fly autonomously or be piloted remotely. This system includes a portable control station for the operator and one or more Unmanned Aerial Vehicles (UAVs). The UAVs can collect and process data through various sensors, such as video or still cameras, including far and near infrared, radar or laser based range finders, or specialized communication devices. Most UASs are capable of real-time data transfer between the UAV(s) and the control station; some have additional on-board data storage capabilities for enhanced data collection tasks. UASs can perform tasks similar to those that can be done by manned aerial vehicles, but often faster, safer, and at a lower cost.
UASs have been used to perform inspections of inaccessible areas in forests, monitoring soil erosion, monitoring forest fires, and creating 3D models. Other possible applications of UASs include monitoring or inspecting work in construction and infrastructure, for example, bridge inspections, and construction safety inspections on jobsites. Some U.S. State Departments of Transportation (DOT) are leading UAS application and implementation research, such as Utah DOT and Georgia DOT.
Even with the research that has been done, there are still gaps in our understanding of the particular uses and value of the data that can be collected with these systems. We have focused our efforts in understanding the use and value of images collected with UASs for Construction Management (CM) tasks, such as project progress, jobsite logistics, and quality or safety inspection. Therefore, identifying potential applications of these images is critical to understanding the potential of this emerging technology. Our research group at Georgia Tech conducted UAS test flights at four construction project sites to collect images, followed by interviews with project personnel to collect their perception of the benefits and usefulness of those images.
The exploratory study of the application of UAS-based images for construction management tasks began with a comprehensive review of applications of UASs in various fields. This step provided us with an understanding of the possible uses of images as well as revealing gaps in the understanding of the particular use and value of UAS images for construction management tasks. In order to pursue the goal of our study, we conducted test flights with the UAS to collect images including both still images and videos. The four projects used in this study included three projects in Atlanta, Georgia and one project in the city of Salvador in Brazil. The selected projects included an academic office building, a research building, a school, and a residential high-rise building project. Site visits for obtaining images and testing the UAS were between one and five times per project site from the months of May to November 2014, and each visit lasted between 30 minutes and one hour. We used a consumer grade UAS for the collection of images since we believe that most industry professionals would opt for this option since they are simpler to operate.
From the images collected, we created an image library and we chose a subset of the images for use in interviews with project personnel. A total of 200 images were collected during the seven-month period. The selection of images resulted in an acceptable mix of image types, including photos and videos from a respondent’s project and not from a respondent’s project to reduce bias related to project familiarity. A subset of 15 images was selected for the interviews (eight videos and seven photos). We developed a questionnaire which aimed at collecting the necessary data about respondents and their perceptions about the images obtained at construction sites. We also asked respondents to compare the images with photography services they may use. Four subjects from the projects selected (S1 to S4) were recruited for the interviews. Interviews with project personnel were conducted and the data collected was then analyzed and conclusions drawn.
FINDINGS: USER PERCEPTION OF IMAGE VALUE
A total of 48 images were included in our analysis. From this sample, 11 images were analyzed from the perspective of the subject’s own project and the other 37 images were analyzed from the perspective of another subject’s projects. Findings from the interviews with project personnel regarding their perceptions about the following aspects revealed possible uses of the images viewed and included: (a) usability, for issues such as jobsite logistics, safety conditions, project progress, quality control, general managerial issues (marketing, worker and subcontractors education), and technical issues, (b) identification of managerial or technical problems and potential technical actions stemming from the observed visual asset, as well as (c) preferences and requirements, such as closer views, interior views, higher elevation views, specific view angle, workers performing tasks, and photo or video preferences.
Project personnel were able to identify more issues from images related to their own project than other projects. However, we observed some reluctance from project personnel to point out issues with their projects. Most interviewees agreed in the usefulness of the assets from projects that were not their own for training purposes since knowledge of one’s own project can desensitize personnel to problems that may be present on site. It was clear from the interviewees’ responses that their role in the project influenced the perceived usefulness of the images. Field personnel found the images to be more useful for identifying logistics issues and problems at the operational level whereas project management personnel found the images more useful for a big picture view of the project. They focused more on overall logistics and project progress than on details.
POTENTIAL APPLICATION FOR CONSTRUCTION MANAGEMENT TASKS
Project personnel were also asked about their perceptions on usefulness of the images for CM tasks. A seven point Likert scale, where 1 meant strongly agree and 7 strongly disagreed, was used (see Table 1).TABLE 1. USEFULNESS OF IMAGES (Subjects Rating 7-Point Likert Scale)
|Use of Images
Subjects Rating 7-Point Likert Scale
|Project progress monitoring||3||2||1||2||2.00|
For the four project personnel, the images are very useful for project progress monitoring (Avg. 2.00), jobsite logistics (Avg. 2.25) and management issues in general (Avg. 2.75). These findings can be confirmed and compared with the qualitative data from the 48 assets analyzed in this study. Project progress or work progress monitoring usefulness was indicated by the interviewees in 10 out of 15 assets and jobsite logistics was indicated in eight assets and was mentioned as a task related problem identifiable in 11 assets (see Table 2). On the other hand, despite safety conditions having an average rating of 3.25 in the quantitative survey, through interview data we observed that usefulness for this management task was indicated in seven images and in 13 images it was mentioned as useful for identifying problems. This indicates that the images had potential to assist project personnel in the identification of issues on site.
TABLE 2. ASSETS USEFUL FOR CM TASKS OR TASK-RELATED PROBLEM IDENTIFICATION
|Project and work progress||10||-|
|Work quality inspection||5||5|
The goal of this exploratory study was to identify potential applications of images obtained from UAS for construction management tasks and to identify other construction related tasks that deserve further study. A database of 200 images was assembled from test flights performed at three active construction sites in the US and one in Brazil. The usefulness of the images was assessed through interviews with project personnel from the test sites using a subset of 15 images per subject. The findings indicate that there are several potential applications of UAS-based images for CM applications including the monitoring of project progress, evaluation of job site logistics plans, monitoring of safety conditions, and quality inspections of work performed among other management tasks.
The main contribution of this study is the better understanding of the use of UAS-based images for CM tasks, indicating relevant opportunities to explore this emerging technology on jobsites. Some issues that will need to be researched further include the impact of the regulatory environment on the use of UAS, the impact of learning curve in the use of UAS technology by construction personnel, privacy concerns, and safety issues that may be related to the use of UAS on jobsites. Future research should focus on assessing the performance of UAS for the tasks highlighted by this study as well as other tasks that may be considered feasible with UAS technology.
Dr. Javier Irizarry is an Associate Professor in the School of Building Construction at Georgia Tech and Director of the CONECTech Lab. He is a Licensed Professional Engineer and holds a BS in Civil Engineering from the University of Puerto Rico, a Masters in Engineering Management from the Polytechnic University of Puerto Rico and a PhD in Civil Engineering from Purdue University.
Dr. Dayana Bastos Costa, is a Visiting Scholar in the School of Building Construction at the Georgia Institute of Technology and an Assistant Professor of Construction Management at the Structural and Construction Engineering Department, School of Engineering, Federal University of Bahia–Brazil (UFBA).