Prior to development of these Guidelines, a literature review and questionnaire were completed to document the current state of the art of mobile LIDAR usage in transportation applications.
2.1.1 Literature review
A thorough review of available literature was conducted to ensure that the Guidelines development team and oversight panel were fully informed of recent advancements in mobile LIDAR technology, techniques, and applications in transportation. Research documents were obtained from industry magazines and websites, technical reports, peer-reviewed journals, and conference presentations produced by industry leaders across the globe.
The literature review touches briefly on the basics of LIDAR technology followed by a more in – depth description of current mobile LIDAR trends, including systems components and software. This review also provides insights on current and emerging applications of mobile LIDAR for transportation agencies through industry projects and academic research. An overview of existing quality control procedures used to verify the accuracy of the collected data is presented. A collection of case studies provides a clear description of the advantages of mobile LIDAR, including an increase in safety and efficiency.
The final portions of the review identify current challenges the industry is facing, guidelines that currently exist, and what else is needed to streamline the adoption of mobile LIDAR by transportation agencies.
In summary, there is a lot of discussion of “what” is being done in practice, but not a lot of information regarding “how” and “how well” it is being done. A willingness to share information going forward will be important to the successful use of mobile LIDAR. Furthermore, this review confirmed the need for a consistent set of national guidelines.
Recommendation: Document pilot projects and publish the results so that others can benefit from your efforts.
The full literature review is presented in Appendix A.
2.1.2 Questionnaire chapter
An online questionnaire was administered to state Departments of Transportation (DOTs) in order to document and evaluate the state-of-the-practice regarding mobile LIDAR usage in transportation applications. Representatives from each of the 50 U.S. state DOTs and 6 additional transportation agencies completed the questionnaire, for a total of 74 responses. A second service provider questionnaire was completed by 14 companies experienced with mobile LIDAR services. Phone interviews were also conducted with the companies.
Many personnel within the DOTs appear to be very interested in the use of scanning technology and feel that it will become a critical part of their operations over the next 5 years. The DOTs identified several applications for which they currently use mobile LIDAR and stated that they foresee expanding the use of the technology into numerous transportation applications. The level of expertise related to mobile LIDAR among the DOTs showed substantial variability, particularly as compared to static scanning. Interestingly, more DOTs have used mobile than airborne LIDAR within the last year, even though mobile LIDAR technologies are comparatively less established.
Responders cited many challenges, both organizational and technical, that must be addressed before transportation agencies can optimize the use of mobile LIDAR and completely integrate it into their workflows. One of the most significant challenges identified was cost. This finding indicates that the respondents are not clear where savings come from and what the return on investment is from mobile LIDAR. Additional education and evidence may be required to overcome this hurdle.
Comparison of the DOT and service provider questionnaire results highlighted key differences between the perceptions of DOTs and service providers on the utility of 3D data. Most significantly, many service providers felt that DOTs were far from a transition to 3D workflows. However, most DOTs stated that they had transitioned or were well into the process of transitioning. These data reveal an important disconnect between the people responsible for acquiring LIDAR data and those responsible for the design workflows. As mobile LIDAR usage expands, it becomes increasingly important for both DOTs and service providers to understand how 3D data can be integrated into DOT workflows. All responders agreed that there are many challenges to overcome for a complete transition to 3D within the transportation agencies.
A full report of the questionnaires and key results are presented in Appendix B.
2.2 Organization of document
Given the wide audience for this document and their varying experience with geospatial technologies and management responsibilities, this document has been divided into two parts followed by appendices:
- Part I – Management Considerations. This part of the document contains vital information to aid management in determining what types of applications can be enhanced with mobile LIDAR, general needs and considerations for using mobile LIDAR, cost considerations, data management, and guidance in selecting mobile LIDAR for a project.
- Part II – Technical Details. This part was developed for personnel who have more technical expertise and would likely be overseeing the quality control aspects of a project as well as developing technical information and requirements for a statement of work.
- Appendices. Several appendices are included in this document, including:
- Appendix A: Literature Review. Herein, the result of the literature review and key findings are presented.
- Appendix B: Questionnaire Report. This appendix presents the results to the questions asked of transportation personnel and mobile LIDAR service providers. Key results are summarized.
- Appendix C: Statement of Work (Outline). An outline for a statement of work is presented with important considerations to ensure proper communication of project needs.
- Appendix D: Sample Calibration Report. This sample calibration form can be used by the data providers to report critical information regarding the calibration process.
- Appendix E: Current Storage Formats. This appendix discusses current data storage formats used for LIDAR data.
- Appendix F: Additional Considerations. These Guidelines focus on geometric accuracy and point density evaluation. Other metrics such as completeness and classification accuracy are presented in this appendix.
- Appendix G: Glossary. A glossary of terminology (>125 terms) for mobile LIDAR and relevant geomatics fundamentals are presented in this appendix.
- Appendix H: References. A reference list is provided for the entire document.