BACKGROUND
There has been increasing interest and use of unmanned aerial systems (UAS) in the past 10 years. One application of considerable interest to transportation agencies and their private sector partners is supplementing highway bridge inspections. There is particular interest in performing safety inspections of bridge elements that are typically costly for bridge owners. By using UAS, the bridge superstructure and substructure can be assessed without requiring closing lanes of traffic or exposing inspectors to traffic. For bridges over rivers or other water bodies, UAS can collect data underneath or along the fascia without the need to close traffic lanes to use a snooper truck or similar system for inspection of hard-to-access bridge elements.
However, research has not yet focused on the ability of UAS technologies to support collection of element-level bridge inspection data in accordance with the AASHTO Manual for Bridge Element Inspection (MBEI) methodology and format. There is a need to provide guidelines for state departments of transportation (DOTs) to select the appropriate UAS technologies for element-level bridge inspection. This research will help foster innovation in bridge inspection and safety.
OBJECTIVE
The objective of this research was to develop AASHTO guidelines to assist state DOTs with using UAS technologies for inspection and assessment of bridge element conditions. The research included:
- Developing a selection process of appropriate UAS technologies to supplement conventional inspection methods for data collection and assessment of the overall bridge condition and bridge element-level defects in accordance with the MBEI methodology and format;
- Developing UAS technologies operator and bridge inspection team qualifications;
- Comparing UAS technologies and conventional bridge inspection methods in respect to time, cost, quality, data consistency, traffic impact, and safety; and
- Developing a standalone roadmap including the requirements for implementing the UAS technologies by state DOTs including IT infrastructure and security, data retention policy, organization structure and workflow, and training.
Accomplishment of the project objective required at least the following tasks.
TASKS
PHASE I—Planning
Task 1. Conduct a literature review of relevant research and current state of practice related to UAS technologies for inspection and assessment of bridge element conditions, and other infrastructures. The review shall include published and unpublished research conducted through the NCHRP; FHWA; and other national, international, state, and pooled-fund sponsored research.
Task 2. Identify the required data, to be collected in Phase II, in order to achieve the research objective. Propose eight agencies to collect data from different UAS technologies, bridge characteristics, and bridge element defects. From these eight proposed agencies, the NCHRP project panel will select a minimum of 20 bridges from four agencies for data collections. The research team shall plan to use UAS to conduct bridge element-level inspections, as needed, if the data are not available.
Task 3. Synthesize the Tasks 1 and 2 to identify the knowledge gaps for the applications of UAS technologies for inspection and assessment of bridge element conditions. These gaps should be addressed in this research or, as budget permits, in the recommendations for future research.
Task 4. Propose a methodology to evaluate and implement the applications of UAS technologies for inspection and assessment of bridge element conditions, to be fully developed in Phase II.
At a minimum, the methodology shall include a set of applicable metrics including the following:
- bridge characteristics, bridge element types and defects, and condition assessment process for selecting the appropriate UAS technologies;
- UAS technologies types and accuracy levels;
- UAS data processing and reporting requirements;
- the advantages and disadvantages of UAS technologies versus conventional inspection methods (e.g., different sensors, accuracy levels, time and cost, operation restrictions, in-house and outsource inspection policy, repeatability, ease of use);
- the readiness of off the shelf UAS technologies to be implemented by DOTs for bridge element-level inspection;
- the requirements for implementing the UAS technologies including IT infrastructure and security, data retention policy, organization structure and workflow, and training.
Task 5. Propose a preliminary outline for the guidelines based on the proposed methodology.
Task 6. Prepare Interim Report No. 1 that documents Tasks 1 through 5, includes the data archiving plan (see Special Note C), and provides an updated work plan for the remainder of the research. This report must be submitted to NCHRP no later than 4 months after contract execution. The updated work plan must describe the process and rationale for the work proposed for Phases II though IV.
PHASE II—Data Collection and Methodology Development
Task 7. Collect and analyze data for 20 bridges from the four selected DOTs to achieve the research objective. Data should be augmented by documented research according to the approved Interim Report No.1. The research team is expected to conduct UAS bridge element-level inspection to collect and supplement unavailable data.
Task 8. Develop the methodology according to the approved Interim Report No.1.
Task 9. Provide a detailed description of every chapter and section of the proposed guidelines and complete a sample chapter of the proposed guidelines selected by NCHRP. This chapter should be publication-ready.
Task 10. Prepare Interim Report No. 2 that documents the results of Tasks 7 through 9 and provides an updated work plan for the remainder of the project. This report is due no later than 12 months after approval of Phase I. The updated plan must describe the work proposed for Phases III and IV.
PHASE III—Guidelines Development
Task 11. Develop the guidelines according to the approved Interim Report No. 2 and the standalone roadmap described in the research objective.
Task 12. Prepare Interim Report No. 3 that documents the results of Task 11 no later than 6 months after approval of Phase II. The updated work plan must describe the work proposed for Phase IV.
PHASE IV—Final Products
Task 13. Revise the draft guidelines considering the NCHRP’s review comments.
Task 14. Prepare final deliverables including: (1) the proposed AASHTO guidelines for the applications of UAS technologies for inspection and assessment of bridge element conditions, (2) a final report that documents the entire research effort, (3) the standalone roadmap, and (4) a stand-alone technical memorandum titled “Implementation of Research Findings and Products.” See Special Note E for additional information. The draft deliverables are due no later than 2 months after approval of Phase III.
STATUS: Will be published as NCHRP Research Report 1114.
