NCHRP Report 748 presents guidelines for the application of mobile 3D light detection and ranging
(LIDAR) technology. The intended audience includes management and technical staff responsible for procurement of this technology and its use in the planning, design, construction, and maintenance of transportation facilities. The guidelines will assist both transportation agencies and the service provider community with the introduction and adoption of this technology by establishing a published standard reference and common basis for understanding and communication. This document is organized into two main parts: 1) management and decision making, and 2) technical considerations.
1. Management and Decision Making: This section provides guidance on the use and integration of mobile LIDAR system (MLS) data for a wide range of transportation applications without requiring an in-depth knowledge of the technology. The following list includes potential data elements and applications in safety and asset management as described in the report. Note that there are other applications of MLS data in project planning, project development, construction, maintenance, operations.
a. Safety
i. Extraction of Geometric Properties and Features for Safety Analyses: MLS point clouds can be used to obtain common geometric information (e.g., grade, slope, width of road/lanes, locations of signs, etc.) for visibility and other safety analyses (e.g., stopping sight distance). Safety investigations can be done virtually within the 3D point cloud.
ii. Forensics and Accident Investigation: For post-disaster surveys, crashed vehicles may block necessary views of the scene, so static scanning will generally be a better choice. However, routine MLS surveys can provide detailed information of road surface characteristics (e.g., grade, slope, width, etc.) to support forensic analysis.
iii. Driver Assistance and Autonomous Navigation: MLS data can provide input models used by driver assistance and autonomous navigation systems.
b. Asset Management
i. Asset Management, Modeling and Inspection, Inventory Mapping, and GIS: Attributes will need to be applied to MLS datasets through manual or semi-automatic processes using data from other sources.
ii. Sign and Billboard Inventory: Semi-automatic and automatic processes exist for extracting signs. Appropriate point cloud density may be difficult to achieve on a sign; however, imagery provides more detail.
2. Technical Considerations: This section provides the details needed to completely specify the project requirements and deliverables. Mobile LIDAR system components include laser scanners, global navigation satellite system (GNSS) receivers, internal measurement units (IMUs), digital cameras, and other ancillary devices.
The report includes the results of a survey conducted of all 50 states and interviews with 14 service providers. The guidelines also provide general recommendations concerning the critical issue of data management and address the issue of implementation.