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Highway Infrastructure Inspection Practices for the Digital Age (2022)

Chapter: Chapter 5 - Summary of Findings

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Page 99
Suggested Citation:"Chapter 5 - Summary of Findings." National Academies of Sciences, Engineering, and Medicine. 2022. Highway Infrastructure Inspection Practices for the Digital Age. Washington, DC: The National Academies Press. doi: 10.17226/26592.
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Page 100
Suggested Citation:"Chapter 5 - Summary of Findings." National Academies of Sciences, Engineering, and Medicine. 2022. Highway Infrastructure Inspection Practices for the Digital Age. Washington, DC: The National Academies Press. doi: 10.17226/26592.
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Suggested Citation:"Chapter 5 - Summary of Findings." National Academies of Sciences, Engineering, and Medicine. 2022. Highway Infrastructure Inspection Practices for the Digital Age. Washington, DC: The National Academies Press. doi: 10.17226/26592.
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Suggested Citation:"Chapter 5 - Summary of Findings." National Academies of Sciences, Engineering, and Medicine. 2022. Highway Infrastructure Inspection Practices for the Digital Age. Washington, DC: The National Academies Press. doi: 10.17226/26592.
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Suggested Citation:"Chapter 5 - Summary of Findings." National Academies of Sciences, Engineering, and Medicine. 2022. Highway Infrastructure Inspection Practices for the Digital Age. Washington, DC: The National Academies Press. doi: 10.17226/26592.
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99   Summary of Findings Introduction Highway infrastructure inspection is critical in any transportation system. With the latest technological advancements, the inspection landscape has been rapidly changing through incor- poration of technologies. The goal of this synthesis is to document the state of practice by state DOTs for using various technologies to inspect highway infrastructure during construction and maintenance of assets. The literature review, survey of state DOTs, and case examples provide key findings, knowledge gaps, and suggestions for future research in implementing technologies for highway infrastructure inspection. The gaps in knowledge found in this study provide ideas for future research to address those gaps. Major Findings The major findings of this synthesis are based on the literature review, an online survey of state DOTs, and case examples of eight state DOTs. These findings are summarized as follows, in no particular order: 1. Geospatial technologies a. The literature findings indicated that the typical applications of geospatial technologies related to highway infrastructure inspection include earthwork, paving, verification, as-built surveys, site and progress monitoring, quality assurance and quality control, and asset management. b. Eighty-one percent of the 32 state DOT survey respondents that use geospatial tech- nologies have used GNSS and GPS for inspection of highway infrastructure during con- struction. The top inspection activities for GNSS and GPS technologies during highway construction include earthwork inspection and quantities, verification and documenta- tion of work completed, and collection of as-built information. c. Thirty-eight percent of these 32 DOTs have used GNSS and GPS for inspection of highway infrastructure during maintenance of assets. The top inspection activities for GNSS and GPS technologies used for asset management include inventories and inspection of sign- age, culverts, guardrails, and other assets; sharing asset information between different functional units within the DOT; locating pavement/material placement for performance tracking; and pavement crack and defect detection. d. Fifty-nine percent of these 32 DOTs have used GIS for inspection of highway infrastruc- ture during maintenance of assets. The top inspection activities using GIS technologies during maintenance of highway infrastructure assets include inventories and inspection of signage, culvert, and guardrails, and sharing asset information between different func- tional units within the DOT. C H A P T E R   5

100 Highway Infrastructure Inspection Practices for the Digital Age e. Forty-seven percent of these 32 DOTs have used GIS for inspection of highway infrastruc- ture during construction. The top inspection activities for the use of GIS during highway construction include collecting as-built information/developing 3D as-built models, capturing site photos and videos, and monitoring construction progress. f. More than 45% of these 32 DOTs indicated that the top five challenges in the implementa- tion of geospatial technologies for highway infrastructure inspection during construction and maintenance of assets are lack of training, knowledge, and skills to use technologies; lack of reliable internet connection in remote locations; cost issues; lack of standard contract specifications; and device maintenance and user support. 2. Remote sensing and monitoring technologies a. The literature findings indicated that LiDAR systems can be used for a wide range of applications, including earthwork, paving, roadway design, AMG and control, quality assurance and quality control, and asset management. In addition, the main applications of RFID for highway infrastructure inspection include tracking PCC test specimens, moni- toring in-place PCC, tracking construction materials, and locating buried infrastructure. The literature review also indicated that IC can be used for pavement layer materials and soils aggregates to improve the quality, uniformity, and long-lasting performance of pavements. b. Seventy-five percent of the 28 DOTs that reported use of remote sensing and monitoring technologies indicated that they have used remote sensors (e.g., accelerometers, maturity meter sensors, or strain gauges) for inspection of highway infrastructure during construc- tion. The top inspection activities for using remote sensors during highway construc- tion include measurement of material strength and temperature (e.g., concrete and base course), quality control and quality assurance, and measurement of pavement thickness. c. Twenty-five percent of these 28 DOTs indicated that they have used remote sensors (e.g., accelerometers, maturity meter sensors, or strain gauges) for inspection of highway infrastructure during maintenance of assets. The top inspection activities for using remote sensors during maintenance of highway infrastructure assets include structural inspec- tion, slope stability, and landslide assessment. d. Fifty-four percent of these 28 DOTs indicated that they have used remote cameras for inspection of highway infrastructure during construction. The top inspection activities applied to remote cameras include monitoring construction progress and capturing site photos and videos. e. Thirty-two percent of these 28 DOTs indicated that they have used LiDAR and 3D laser scanning for inspection of highway infrastructure during maintenance of assets. The top inspection activities using LiDAR and 3D laser scanning during maintenance of high- way infrastructure assets include detection of pavement cracks and defects, assessment of slope stability and landslide, and location of material placement for performance tracking. f. More than 30% of the 28 DOTs indicated that the top challenges in using remote sensing and monitoring technologies for highway infrastructure inspection during construction or asset management include cost issues; lack of training, knowledge, and skills to use technologies; device maintenance and user support; lack of reliable internet connection in remote locations; lack of standard contract specifications; and resistance to change. 3. Mobile devices and software applications a. The literature review indicated that the 3D engineered model allows for faster, more accu- rate, and more efficient planning and construction. AMG is a suitable tool for projects that involve large amounts of earthwork or paving, new alignments, or projects requiring accurate digital terrain models. In addition, the main benefits of using handheld devices in highway infrastructure inspection include better organized field-generated data, reduced cycle time to obtain the data, improved accuracy for material delivery, and enhanced electronic documentation and digital inspection. The literature review also indicated that

Summary of Findings 101   the main applications of VR/AR technology for highway inspection include AR-guided site inspection, remote inspection, 4D inspection, and automated inspection. b. Ninety percent of the 41 DOTs that reported use of mobile devices and software appli- cations indicated that they have used tablet computers and smartphones for inspection of highway infrastructure during construction. The top inspection activities that utilize tablets and smartphones during highway construction include verification and documenta- tion of work completed for payment, monitoring of construction progress, and capturing of site photos and videos. c. Thirty-nine percent of the 41 DOTs indicated that they have used tablet computers and smartphones for inspection of highway infrastructure during maintenance of assets. The top inspection activities for using tablets and smartphones during maintenance of highway infrastructure assets include inventories and inspection of signage, culverts, guardrails, and other highway assets, and sharing asset information between different functional units. d. Fifty-four percent of the 41 DOTs indicated that they have used handheld data collectors for inspection of highway infrastructure during construction. The top inspection activi- ties that use handheld data collectors during highway construction include monitoring construction progress, earthwork inspection and quantities, and quality control and qual- ity assurance activities. e. More than 40% of the 39 DOTs that reported use of remote sensing and monitoring tech- nologies indicated that the top challenges in using mobile devices and software appli- cations for highway infrastructure inspection during construction and maintenance of assets include lack of reliable internet connection in remote locations; lack of training, knowledge, and skills to use technologies; cost issues; device maintenance and user sup- port; and resistance to change. 4. Nondestructive evaluation technologies a. The literature review indicated that GPR has a wide range of highway construction appli- cations such as locating underground utilities, mines, caves, tunnels, or other unseen objects without excavation or destruction. Infrared thermography uses sensors to evaluate materials by measuring the surface temperature and its variations below ground. b. More than half of the 28 DOTs that reported use of nondestructive evaluation technolo- gies have used nuclear density gauges (93%), dynamic test loading for piles (86%), cross- hole sonic logging for drilled shafts (75%), surface profile measuring systems (71%), GPR (64%), and ultrasonic testing (57%) for highway inspection during construction. The top inspection activities for using nondestructive evaluation technologies during highway construction include in-situ material characterization, foundation investigation, struc- tural inspection, and identification of bridge deck deterioration. c. More than a quarter of these 28 DOTs have used GPR (39%) and surface profile measuring systems (29%) for inspection of highway infrastructure during maintenance of assets. The top inspection activities applied to nondestructive evaluation technologies during mainte- nance of highway infrastructure assets include structural inspection, real-time automated pavement distress measurements, and identification of fatigue and fracture damage. d. More than 30% of the 21 DOTs that reported use of nondestructive evaluation technologies indicated that the top challenges in using nondestructive evaluation methods for highway infrastructure inspection during construction or for asset management include lack of training, knowledge, and skills to use technologies; cost issues; resistance to change; device maintenance and user support; and lack of reliable internet connection in remote locations. 5. Other emerging technologies a. The literature review indicated that many state DOTs are increasingly using UASs for different purposes, such as site surveying, tracking construction progress, monitoring roadside environmental conditions, or traffic management and safety improvement.

102 Highway Infrastructure Inspection Practices for the Digital Age b. The literature review indicated that e-ticketing has gained substantial momentum over the past 5 years. Additionally, because of the COVID-19 pandemic, many state DOTs are increasingly using or implementing e-ticketing technologies to reduce the risk of virus transmission and improve the safety of inspectors and on-site personnel. The typical benefits of e-ticketing implementation include improved safety, enhanced efficiency, and an offset to staff reductions. c. The survey results revealed that 59% of the 32 DOTs that reported use of geospatial tech- nologies have used e-ticketing for highway infrastructure inspection during construction. The top inspection activities in which e-ticketing is used by DOTs for highway construc- tion include tracking the position of bulk material and verification and documentation of work completed for payment. d. The survey results revealed that 50% of the 32 DOTs that reported use of geospatial tech- nologies have used UASs for highway infrastructure inspection during construction. The top inspection activities using UASs during highway construction include monitoring construction progress and capturing site photos and videos. In addition, 31% of these 32 DOTs have used UASs for highway infrastructure inspection during maintenance of assets. The top inspection activities using UASs during maintenance of highway infra- structure assets include structural inspection, slope stability, and landslide assessment. 6. Evaluation of inspection technologies a. More than two-thirds of the 42 DOTs that responded to the survey have used the follow- ing evaluation metrics to evaluate technologies for highway inspection: efficiencies gained when using technologies (86% of 42 DOT responses), increase in quality of a project (76% of 42 DOT responses), overcoming limited inspection resources (69% of 42 DOT responses), and cost–benefit analysis (68% of 42 DOT responses). b. Fifty-three percent of the 42 DOTs indicated that they do not track the cost-effectiveness, and 33% are unsure about tracking the cost-effectiveness of implementing technologies. c. More than 75% of the 42 DOTs indicated that information is not available for conducting return on investment (ROI) assessments from using the technologies for highway infra- structure inspection. d. More than 70% of the 42 DOTs indicated that the main driving factors for using mobile devices and software applications are to enhance the safety of inspectors, improve effi- ciency, and enhance staffing (using mobile devices and software applications reduces the need for inspection staff). e. More than half of the 42 DOTs indicated that the main driving factors for using geospatial technologies are to improve efficiency, promote e-construction, and enhance the safety of inspectors. f. From its case example, the Illinois DOT noted that it does not have a formal evaluation approach for considering technologies and that a decision to use a technology is not solely cost-based. g. From its case example, the Iowa DOT noted that it evaluates new technologies and inno- vations using an anecdotal approach. The Iowa DOT tries technologies that show promise but then evaluates continued use on the basis of considerations of contract administration burden, time and effort, and long-term goals. 7. Training a. Approximately two-thirds of 42 DOTs indicated that they have provided field-based train- ing, peer training, online training, or classroom-based training for their staff regarding the use of technologies for highway inspection. b. From its case example, NYSDOT realized that using technologies correctly requires training. Additionally, NYSDOT observed the benefits of offering training to employees regularly to learn the technology, as well as refresher training to keep inspectors up to date.

Summary of Findings 103   c. From their case examples, the Oregon and Pennsylvania DOTs noted that providing effective training on the use of technologies helped overcome resistance to change among the staff and inspectors and gain buy-in from users. d. From its case example, the Minnesota DOT recognized that having the right staff that possesses the proper training and knowledge, along with having enough resources available, makes a positive difference for implementing technology use. e. From its case example, PennDOT noted that one of the challenges in using technol- ogies to replace traditional methods was gaining buy-in from users and providing proper training to the staff and inspectors. Additionally, training also varied depending on the staff members being trained and the work that was to be performed with a specific technology. Suggestions for Future Research The gaps in knowledge and practice identified in this synthesis serve as a point of departure to explore the potential for future research. To promote effective use of technologies for inspection of highway infrastructure during construction and maintenance of assets, future research is suggested in the following areas: 1. There is a lack of guidance on how inspection technologies can effectively be used to offset limited inspection resources. Future research could help develop a framework to empirically investigate the relationships between inspection technologies and allocation of inspection resources during construction and asset management. 2. Conducting benefit–cost analyses and performing return on investment assessments are essential for evaluating the effectiveness of technology implementation. However, there is a lack of a formal framework to perform benefit–cost analyses and return on investment assess- ments when investigating the value of a technology for use in inspections. Future research is suggested to develop guidance on conducting benefit–cost analysis and empirically derived calculation of return on investment of inspection technologies for highway infrastructure. The guidance could include assessments of the value of using technologies for inspections compared with traditional inspection methods. 3. Many of the synthesis responses noted that buy-in and training influence the success of implementing inspection technologies for highway construction inspection. Future research is suggested to investigate how to gain buy-in from users and leadership in order to develop effective training methods as well as core skill sets and competence for inspectors in the use of various inspection technologies during construction and asset management.

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Historically, state departments of transportation (DOTs) have employed on-site workforces to execute infrastructure inspection using traditional inspection methods.

The TRB National Cooperative Highway Research Program's NCHRP Synthesis 582: Highway Infrastructure Inspection Practices for the Digital Age documents the various technologies - such as unmanned aircraft systems (UASs), embedded and remote sensors, intelligent machines, mobile devices, and new software applications - used by DOTs to inspect highway infrastructure during construction and maintenance of assets.

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