National Academies Press: OpenBook

Use of Unmanned Aerial Systems for Highway Construction (2022)

Chapter: Chapter 3 - State of the Practice

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Suggested Citation:"Chapter 3 - State of the Practice." National Academies of Sciences, Engineering, and Medicine. 2022. Use of Unmanned Aerial Systems for Highway Construction. Washington, DC: The National Academies Press. doi: 10.17226/26546.
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Suggested Citation:"Chapter 3 - State of the Practice." National Academies of Sciences, Engineering, and Medicine. 2022. Use of Unmanned Aerial Systems for Highway Construction. Washington, DC: The National Academies Press. doi: 10.17226/26546.
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Suggested Citation:"Chapter 3 - State of the Practice." National Academies of Sciences, Engineering, and Medicine. 2022. Use of Unmanned Aerial Systems for Highway Construction. Washington, DC: The National Academies Press. doi: 10.17226/26546.
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Suggested Citation:"Chapter 3 - State of the Practice." National Academies of Sciences, Engineering, and Medicine. 2022. Use of Unmanned Aerial Systems for Highway Construction. Washington, DC: The National Academies Press. doi: 10.17226/26546.
×
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Suggested Citation:"Chapter 3 - State of the Practice." National Academies of Sciences, Engineering, and Medicine. 2022. Use of Unmanned Aerial Systems for Highway Construction. Washington, DC: The National Academies Press. doi: 10.17226/26546.
×
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Suggested Citation:"Chapter 3 - State of the Practice." National Academies of Sciences, Engineering, and Medicine. 2022. Use of Unmanned Aerial Systems for Highway Construction. Washington, DC: The National Academies Press. doi: 10.17226/26546.
×
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Suggested Citation:"Chapter 3 - State of the Practice." National Academies of Sciences, Engineering, and Medicine. 2022. Use of Unmanned Aerial Systems for Highway Construction. Washington, DC: The National Academies Press. doi: 10.17226/26546.
×
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Suggested Citation:"Chapter 3 - State of the Practice." National Academies of Sciences, Engineering, and Medicine. 2022. Use of Unmanned Aerial Systems for Highway Construction. Washington, DC: The National Academies Press. doi: 10.17226/26546.
×
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Suggested Citation:"Chapter 3 - State of the Practice." National Academies of Sciences, Engineering, and Medicine. 2022. Use of Unmanned Aerial Systems for Highway Construction. Washington, DC: The National Academies Press. doi: 10.17226/26546.
×
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Suggested Citation:"Chapter 3 - State of the Practice." National Academies of Sciences, Engineering, and Medicine. 2022. Use of Unmanned Aerial Systems for Highway Construction. Washington, DC: The National Academies Press. doi: 10.17226/26546.
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Page 19

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10 State of the Practice As noted in Chapter 1, an online survey questionnaire was built by Qualtrics and distributed by email to state DOT personnel who are members of the Council on Aviation, UAS/Advanced Air Mobility, and research advisory committees. A total of 48 responses that represent participa- tion by 48 state DOTs were received from the survey, corresponding to a 94.1% response rate from 51 DOTs, including the District of Columbia. Figure 1 depicts the states, along with the District of Columbia, that participated in the survey, and Figure 2 shows the distribution of position description of the participants. The complete survey questionnaire can be found in Appendix A. Responses to the survey from individual DOTs are aggregated in Appendix B. This chapter reports on results from each of the survey questions. 3.1 Current Use of Unmanned Aerial Systems for Highway Construction Respondents were asked to indicate whether their agency worked on any highway construc- tion projects that used UAS. As can be seen in Figure 1, the South Dakota and New Mexico DOTs and the District of Columbia DOT indicated that they have not used UAS on any of their projects. All of the remaining participants, a total of 45, indicated that they have used UAS on at least one highway construction project. Next, they were asked to indicate how UAS is being used by their agency for highway construction where the agency could select more than one application. From seven common applications provided in the survey (Figure 3), using UAS for aerial surveying is the most common application voted by 72.9% of participating DOTs that responded positively on UAS use, which is followed by monitoring work progress (68.8% of participating DOTs), measuring stockpile, inspecting and documenting erosion and sediment control (54.2% of participating DOTs), mapping (52.1% of participating DOTs), and performing routine quality inspection (43.8% of participating DOTs). Only 29.2% of participat- ing DOTs use UAS to perform work safety inspection. A total of 19 state DOTs mentioned that they used UAS for other purposes. Note that not all of the applications are related to highway construction, and several of the participants who selected “others” typed in more than one area of application. Finally, several of these other applications—such as communications, public outreach, property appraisal, and asset management—were repeated multiple times and are entered only once in the following list: • Public outreach/relations; • Communications; • Public relations and highway safety; • Wetland studies, bat monitoring, subaquatic vegetation, and rail inspection; • Surveying; • Construction progress, quantities, safety, and design data collection; C H A P T E R   3

State of the Practice 11   21% 58% Construction Management TeamInnovation and Technology (UAS Program) Survey Team Research Program Security planner 15% 4% 2% Figure 1. Map of DOTs that participated in the survey, N = 48. Figure 2. Participants’ position descriptions in their agencies.

12 Use of Unmanned Aerial Systems for Highway Construction • Bridge/infrastructure inspection, mining-related survey; • 3-D modeling of rock faces, planning, engagement; • Bridge damage review; • ermal survey, design-level survey, UAV lidar, and bridge inspections; • Property appraisal/management for right-of-way acquisition; • Identify landslide scarps and recent movement; • Rockfall and avalanche mitigation; • Asset management; • Monitoring quarry walls; and • Environmental documentation, legal/claims documentation. 3.2 Practices for Implementing Unmanned Aerial Systems In the second part of the survey, respondents were asked ve questions covering UAS- specic technical and logistical details. First, respondents were asked to indicate who provides UAS services for the applications they selected in Question 3. e options were (1) sta in your organization, (2) third-party service rm or drone service rm, and (3) both (sta in your organization and third-party service). Figure 4 presents the results for the seven common applications provided in Question 3 as well as for the other applications provided by the survey participants. A total of 197 responses were obtained; 96 of the responses (48.7%) indicated that sta in their organization perform various tasks using UAS, while 25 of the responses (12.7%) indicated that they obtain the services of a third-party service rm and 76 of the responses (38.6%) indicated that they use both sta in their organization and third-party service rms. us, it can be concluded that the most common practice for using UAS is to have in-house sta collect and analyze UAS data. Next, respondents were asked about the ight mode used for each of the use cases they selected in Question 3. e participants were given four options to choose from: (1) manual, Figure 3. UAS applications in highway construction by state DOTs.

State of the Practice 13   (2) fully autonomous, (3) both (manual and fully autonomous), and (4) I do not know. As seen in Figure 5, the majority of the respondents indicated that they use both manual and fully autonomous flight modes (47.7%). This is followed by manual flight mode (26.9%). Autonomous flight mode is the least common (22.3%) across all applications, while a total of 15 participants indicated that they use fully autonomous mode for aerial surveying. This is a result of the nature of aerial surveying, for which close-up pictures or videos are not required. On the other hand, performing work safety inspections, for example, would require close-up views and therefore, would often require manual flights. Following the question related to flight modes used for various tasks in highway construc- tion, respondents were asked to indicate the selection criteria that they use to choose the UAS Figure 4. State DOTs’ use of different UAS service providers for different highway construction applications. Figure 5. State DOTs’ use of different UAS flight modes for different highway construction applications.

14 Use of Unmanned Aerial Systems for Highway Construction platform for each of the use cases they selected in Question 3. The respondents were given seven options to choose from where they could type in their answers: (1) cost; (2) flight time per battery; (3) feature(s) (e.g., object avoidance system or flight path planning); (4) documentation/guidance for implementation; (5) no criteria; (6) I do not know; and (7) others, please specify. As seen in Figure 6, the top three criteria were features such as object avoidance or path planning (26.2%), cost (24.3%), and flight time per battery (23.3%), followed by documentation/guidance for implementation (10.6%), others (8.7%), no criteria (4.2%), and “I do not know” (2.6%). Under the “others” category, respondents indicated the following as part of their selection criteria: payload capability, camera specifications, size, parachute (safety), area of interest (AOI) size, quality of camera, and sensor capability. Next, respondents were asked about the sensor types used on the UAS platform for each of the use cases they selected in Question 3. The respondents were given five options to choose from where they could type in answers: (1) digital camera (e.g., onboard, point-and-shoot and action cameras attached to UAS, or with or without high optical zoom); (2) lidar; (3) thermal camera; (4) I do not know; and (5) others, please specify. As seen in Figure 7, the most used sensor is digital camera (72.7%) followed by lidar (15.2%), which is mostly used to provide aerial surveying tasks. There are a few agencies using thermal cameras (5.4%) mostly to inspect erosion and sediment control. Under the “others” category, one of the respondents indicated that their agency is planning to obtain a lidar system and thermal sensor in 2021. Another respondent indicated that they use GPS units attached to their drones. Following the sensor-type question, respondents were asked to indicate the software pack- ages they use for post-processing, sharing, and storing the data for the use cases they selected in Question 3. The participants were given four options to choose from where they could type in answers: (1) photogrammetry software for 3-D modeling (e.g., Agisoft or Pix4D); (2) application-specific software (e.g., GEOPAK or Autodesk Civil 3D); (3) data management software; and (4) others, please specify. As seen in Figure 8, photogrammetry software (49.2%) is the most used data processing software followed by data management software (24.7%), application-specific software packages such as GEOPAK or Autodesk Civil 3D (24.7%), and other software applications (7.3%). The other software applications included Esri, Adobe Lightroom and Photoshop, DroneDeploy, Context Capture, and Terrasolid. Also, several of the respondents indicated that they just deliver the raw images or videos. 3.3 Cost Factors Considered in Making Program Decisions In the third part of the survey, respondents were asked to indicate the cost factor that most affects the respondent agency’s decision making in using UAS for highway construction projects for the use cases they selected in Question 3. The respondents were given five options to choose from: (1) aircraft and sensor cost, (2) software cost, (3) professionals, (4) training costs, and (5) I do not know. As seen in Figure 9, the cost of aircraft and sensing equipment (45.3%) is the major factor that most affects their agency’s decision making in using UAS for all seven applica- tions. That factor is followed by “I do not know” (18.8%), the cost of software (16.5%), training (12.4%), and professionals (7.1%). 3.4 Benefits Realized The respondents were asked to indicate the benefits realized by using UAS for the use cases they selected in Question 3. The respondents were provided with seven options to choose from where they could type in their answers, including (1) cost saving, (2) time saving, (3) safety

Figure 6. State DOTs’ UAS selection criteria for different highway construction applications.

16 Use of Unmanned Aerial Systems for Highway Construction Figure 7. UAS sensors used by state DOTs for different highway construction applications. Figure 8. Types of software used by state DOTs for processing UAS data for different highway construction applications.

State of the Practice 17   improvement, (4) quality improvement, (5) improved documentation/data management, (6) I do not know, and (7) others, please specify. As seen in Figure 10, the most selected benefits were cost savings (23.1%), time savings (21.4%), and improved documentation/data management (18.7%), followed by safety improvement (18.1%), quality improvement (16.2%), “I do not know” (2.2%), and others (0.17%). Only one respondent selected “others” and noted public outreach/media as one of the benefits realized as a result of using UAS in their highway con- struction projects. 3.5 Potential Obstacles to UAS Applications by State Departments of Transportation In the last part of the survey, respondents were asked to indicate the challenges or obstacles for the respondent’s agency in adopting UAS for highway construction. Similar to the pre- vious questions, the respondents answered this question for the applications they selected in Question 3. The respondents were provided with eight options to choose from where they could type in answers: (1) privacy, (2) FAA regulations, (3) registration and liability require- ments, (4) technical expertise, (5) distracting and stressing construction workers, (6) training and workforce, (7) funding, and (8) others, please specify. As seen in Figure 11, the answers vary but the challenges or obstacles repeated the most frequently are FAA regulations (23.0%), train- ing and workforce (22.7%), and the availability of funding to be invested in a UAS program (20.6%). These answers are followed by technical expertise (15.9%), registration and liability requirements (4.8%), others (2.2%), and distracting and stressing construction workers (1.5%). The other challenges that were indicated by the respondents included software tools to fully implement UAS data and training, work regulations, unavailability of drones and lack of visual observers, and construction staff already overcommitted. Figure 9. Cost factors affecting DOTs’ decision making in using UAS for highway construction applications.

Figure 10. Perceived benefits of using UAS by state DOTs in highway construction.

Figure 11. Challenges or obstacles faced by state DOTs when using UAS in highway construction.

Next: Chapter 4 - Case Examples »
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In the last decade, new technologies have transformed all stages of highway construction as more industry stakeholders have begun incorporating new technologies into their daily construction activities.

The TRB National Cooperative Highway Research Program's NCHRP Synthesis 578: Use of Unmanned Aerial Systems for Highway Construction documents the use of Unmanned Aircraft Systems (UAS) by state departments of transportation (DOTs) during highway construction, identifies potential benefits and obstacles DOTs face when implementing UAS in highway construction projects, and identifies information gaps to be filled that could enable state DOTs to enhance the benefits of UAS for construction-related operations.

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