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Comprehensive Application Of Vehicle-Mounted And Airborne 3D Laser Measurement System In Highway Reconstruction And Expansion
With the development of economy, the rapid expansion of cities, and the increasing traffic volume, the carrying space of highway network is becoming saturated. Compared with newly built highways, the construction and land occupation costs of reconstruction and expansion projects are relatively low, which is one of the effective ways to solve the pressure on the road network at present. Highway reconstruction and expansion is a relatively complex project. It is necessary to conduct detailed surveys of the original highway and the topography within a certain bandwidth on both sides before design and construction.
1. Project Overview
Figure 1. Project background
A highway in a certain place in Central China is planned to be expanded and upgraded. It is necessary to obtain 3D results (DEM, DOM, DLG) within a range of 30km along the road and 250m on both sides of the center line. The measurement accuracy of the road surface requires a plane of 5cm and an elevation of 2cm, the area outside the road surface shall meet the 1:2000 topographic map measurement requirements.
2. Project Requirements and Difficulties
1) Project Requirements
It is necessary to obtain 3D results (DEM, DOM, DLG) within a range of 30km on the road and 250m on both sides of the center line in this project; the measurement accuracy of the road surface requires a plane of 5cm and an elevation of 2cm; the area outside the road surface shall meet the 1:2000 topographic map measurement requirements.
2) Project Difficulties
The single 3D laser measurement system based on vehicle laser measurement or airborne laser measurement still has some limitations in the reconstruction and expansion of expressway. The vehicle mounted laser mobile measurement system has a certain measurement blind area on the outer area of the road slope. Compared with the vehicle mounted laser mobile measurement system, the measurement accuracy of airborne laser mobile measurement is lower, and more stringent operation specifications are required.
3. Solution
In order to meet the technical requirements of the road surface measurement in reconstruction and expansion, the project adopts the dual system measurement method of the combination of vehicle mounted and airborne laser mobile measurement, to carry out a detailed survey of the topography and landform of the highway and in a certain width on both side of the highway.
The technical route of the dual system of vehicle mounted and airborne laser mobile measurement is shown in the figure below.
Figure 2. Overall technical process
HiScan-R vehicle mounted laser mobile measurement system is used in the highway to quickly obtain high-density point cloud data of the road surface.
The ARS-1000L airborne laser mobile measurement system is used to collect point cloud data in the bandwidth on both side of the highway. Its data acquisition ability in areas with large elevation difference and vegetation coverage is much higher than that of traditional aerial survey.
Figure 3. HiScan-R vehicle-mounted laser mobile measurement system (upper) and ARS-1000L airborne laser mobile measurement system (lower)
4. Data Achievement
1) Accuracy Verification
In this project, 128 verification points are arranged along the road surface to measure their plane coordinates and leveling elevation, and then extract the corresponding feature point coordinates from the point cloud data to check the accuracy of the results of the vehicle mounted laser mobile measurement system. It can be seen from Table 1 that the plane accuracy of the point cloud data is better than 5cm, and the elevation accuracy is better than 2cm.
Table 1. Accuracy verification table of vehicle mounted laser mobile measurement system
In the survey area, 90 feature points are evenly selected, and then corresponding coordinate values are extracted from the point cloud data collected by the airborne laser mobile measurement system by line intersection for accuracy comparison. It can be seen from Table 2 that the plane and elevation accuracy of the point cloud data are better than 15cm.
Table 2. Accuracy verification table of airborne laser mobile measurement system
In conclusion, the dual-system measurement mode can meet the measurement accuracy requirements of highway reconstruction and expansion projects.
2) Surveying and Mapping Results
Based on the point cloud and image data obtained by the dual system, 3D results can be quickly generated.
Figure 4. Schematic diagram of road surface feature points
Figure 5. Production software
Figure 6. Point cloud data
Figure 7. Point cloud data of the airborne laser mobile measurement system (left) and the point cloud data of the vehicle mounted laser mobile measurement system (right)
Figure 8. 1:2000 DLG (left) and DEM (right)
Figure 9. Longitudinal and Cross-sectional view of highway
5. Project Summary
Based on the dual-system measurement mode of the vehicle mounted laser mobile measurement system and the airborne laser mobile measurement system, the complementary advantages of the dual systems can be realized, which can effectively solve problems of the measurement blind area of the vehicle mounted laser mobile measurement system outside the slope and the difficulty of airborne laser mobile system to meet the requirement of highway surface measurement accuracy. The work efficiency is significantly improved.
6. Products Recommended
HiScan-R vehicle-mounted laser mobile measurement system;
HiScan-Z vehicle-mounted laser mobile measurement system;
ARS-1000L airborne laser mobile measurement system.
Figure 10. HiScan-R vehicle-mounted laser mobile measurement system
Figure 11. HiScan-Z vehicle-mounted laser mobile measurement system
