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Bridge Inspection Workflow Using DJI Matrice 300 RTK+L1

Updated: Oct 22, 2023

Bridges are very important structures for transporting people and goods. For this reason, regular inspections are useful and necessary to ensure continuous and safe operation and extend service life. This is very important for bridges that are prone to structural deterioration, aging and mechanical damage due to stress fatigue, thermal expansion and/or contraction, and concrete delamination and cracking. The latter is considered one of the most important parameters for monitoring and evaluating structural health.


There are many different bridges, but they are usually divided into three main sections: i) Foundation, ii) Substructure, iii) Superstructure


The manner that we inspect bridges is changing because of drones. More engineers are deciding to use UAVs instead of conventional techniques like ladders, ropes, snooper trucks, and aerial work platforms (AWPs). And it's clear. For a small fraction of the expense, drones can quickly detect corrosion, cracks, scours, and other issues with bridges. Overall, they outperform conventional bridge inspection techniques in terms of speed, safety, and accuracy.


The use of drones for bridge inspection is a total game-changer. We are observing increased safety, accelerated and simplified inspections, more thorough data collecting, and lower expenses.


DJI MATRICE 300 RTK

DJI Matrice 300 RTK

Modern unmanned aerial vehicles (UAVs) like the Matrice 300 RTK combine real-time kinematik (RTK) navigation and cutting-edge artificial intelligence. By synchronizing drone footage with GPS data as it is flying, RTK enables exact placement. This has a significant advantage because it eliminates the need for ground control points (GCPs) to achieve the same level of accuracy. GCPs cannot be erected due to roads, valleys, and water below bridges.

By storing locations, angles, and framings, the AI Spot Check feature of the drone can pinpoint points of interest. By taking the same picture at several periods, you can carry out automatic routine inspections in this manner.

When it comes to gear, the Matrice 300 RTK includes 3 gimbals and 6 directional sensors, including one upward gimbal that is ideal for difficult angles on bridges.


The Matrice 300 RTK also provides you more than enough time to finish a full bridge inspection in one go thanks to its exceptional 55-minute battery life. Additionally, it can operate in temperatures between -4° and 122° F (-20° to 50° C) and fly at speeds of up to 51 MPH (82 km/h) and 33.5 MPH (54 km/h), respectively.

The health management system on the Matrice 300 RTK also provides the current condition of all systems, notification records, and even initial troubleshooting. We suggest the Matrice 300 RTK as a strong, reliable, all-around drone for inspecting bridges.



UAV-Lidar – Zenmuse l1

UAV-Lidar – Zenmuse l1

LiDAR technology can produce highly accurate 3D data even in difficult survey situations, such as poor lighting, where optical sensors are less efficient. This technology, in conjunction with other sensors, can be put to aerial vehicles to provide accurate 3D measurements. The combined use of UAV-LiDAR technology has yet to be thoroughly studied, particularly for bridge inspections. Moreover, these types of infrastructures and their designs present technological issues that must be investigated, as well as advantages such as less time-consuming methods for both data collecting and processing.

This is a complete and integrated solution for 3D data collecting that includes the DJI Matrice 300 UAV and the proprietary DJI Terra software . The L1 sensor is mounted on a three-axis gimbal and includes an RTK GNSS and IMU system for precise georeferencing of point clouds. It also features an embedded RGB sensor for coloring the clouds. The optical sensor is a 20 MPx 1" CMOS sensor with a global shutter and an 8.8 mm focal length.


The LiDAR system has a worldwide precision of 10 cm in planimetry and 5 cm in height when flying at 50 m AGL and a constant flying speed of 10 m/s. The raw data is gathered in a DJI proprietary format that can only be analyzed and converted to conventional 3D data formats with the DJI Terra Software. The raw data processing is easy and linear, giving the analyst minimal leeway. The parameters that can be defined include reconstruction density (low, medium, and high), accuracy optimization (Yes/No), output format, and reference system.


Benefits of Drone-based Bridge Inspection :

Benefits of Drone-based Bridge Inspection

1. Collecting Comprehensive Bridge Status Information

Compared to drone inspections, traditional bridge inspections are typically difficult, risky, expensive and time consuming. Drones usually offer better and more accurate image quality. Equipped with HD cameras, proximity sensors, and infrared cameras, drones assist engineers in many ways. This allows drones to provide high-quality, detailed images that professionals can use to identify defects, wear, damage and hot spots. Additionally, the integration of drones with drone inspection software for analytics, AI, 3D imaging, and other tools improves the ability to obtain a wider range of information and identify defects such as cracks, chips, wear, delamination, and rust.

2. Eases Bridge Inspection while Lowering Costs

In general, drones offer a faster, safer and cheaper alternative solution for inspecting various bridge structures. It provides a cost-effective solution for analyzing bridge structures, including hard-to-reach locations, while eliminating dangerous and expensive access equipment, ladders, and other specialized inspection equipment. This equipment makes it easier and safer to inspect the condition of the underside of bridges, significantly reducing inspection time and costs. Drones not only reduce the risks associated with traditional methods, but also eliminate the need to close bridges to traffic, saving money and reducing wasted driver time. Ingeneral, drones cause little disruption, reducing the need for traffic control compared to traditional methods.

3. Improved Safety for Workers and Public

Drones can complete most life-threatening tasks much faster and at a fraction of the cost of traditional methods. Eliminates most risks and works in a wide range of weather conditions. This allows you to quickly and reliably check bridges for defects after natural disasters such as storms and hail.


Traditional bridge inspection methods are dangerous not only for workers, but also for the general public and users. Workers often hang from the sides and bottom of bridges to assess key components. Complexity, risks and caveats during inspection will vary depending on the size and design of the bridge. Large bridges over large bodies of water or high-speed rivers are more dangerous, especially with heavy traffic.


In some cases, bridges must be closed to minimize disruption and risk to users. However, for drones, this may not be necessary and employees do not need physical access to the components being inspected. This eliminates the need to suspend workers under bridges and minimizes associated safety hazards such as falls, drowning and car accidents.

4. 3D Modeling of Bridges

Drones help generate 3D models of bridges. They help identify bugs and are useful for future projects. In general, UAVs have better access to nearly all parts of bridges, including sides, tops and bottoms, than human workers. Its capabilities include access to hard-to-reach areas, confined spaces, and other areas difficult for humans to adequately assess. Because of this, the drone takes better and more accurate images and measurements, and when used in conjunction with drone software solutions, helps create his 3D model of the structure. Models are useful for comparison purposes, failure identification, and future development and projects.

5. Easily and quickly identify defects

Drones offer a faster and easier way to identify existing and impending disruptions. This allows engineers and other construction professionals to implement necessary measures, such as repairs, to ensure safe operation of the bridge. UAVs provide technology that enables engineers to perform comprehensive analyzes of bridges, identifying structural defects and areas ofhigh wear. Drones not only make inspections safer and faster, they also simplify the documentation of analysis reports. This is especially true when used with drone inspection software, which also streamlines workflow and defect recording.


Conclusion :


There are numerous advantages using drones for bridge inspections. They considerably improve inspection efficiency and alleviate many of the problems associated with traditional inspections. Your experience and credentials will determine whether you buy a drone or employ a professional drone pilot.


A drone bridge inspection is not a job for inexperienced drone pilots. It is a highly sophisticated operation that necessitates the use of trained and experienced pilots.

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