Bridge Inspection with Drone / UAV / UAS

11. February 2016

Bridge Inspection with Drone: Bridge inspections are benefitting by a drone-driven building stock classification system. Unmanned aircraft systems (UAS), also called drones and UAVs, create detailed and precise orthophotographs, 3D scale models, and frequently monitor structures for deformation.

Bridge inspection – from report to report

Usually a bridge inspection begins with the review of the previously done bridge inspection reports. All previous information is gathered to identify past past critical areas of the bridge, and where possible current defects could be detected. This is done to determine if those defects have been repaired, or alternatively have increased in severity or size. The bridge inspection team can then plan, and organize, the bridge inspection accordingly. In a best case scenario the bridge being inspected, has in the past, gone through a drone inspection – hopefully performed by a professional drone inspection service provider.

In collaboration with Guido Morgenthal Guido Morgenthal Technologien im Bauwesen Ascending Technologieshas inspected several buildings with drone technology. The surveys and inspections were successful in both collecting data, and also in their efficiency. The drone type AscTec Falcon 8 was utilized in each inspection.

Aerial bridge inspection – from downside and above

The inspectors are usually composed of a small team of civil engineers trained as pilots, and a technical expert. The team gets permission to take off in accordance to legal requirements, after they have informed authorities, and possibly coordinated traffic control and access equipment. It is necessary to have a small safe take off area for the vertical launch and landing. A few short flights, from a short distance, are sufficient to carry out the full inspection – depending on the condition of the bridge.

The AscTec Falcon 8 UAS drone is a high performing UAV (Unmanned Aerial Vehicle), which has proven itself with more than 1,000 flight hours. It is a simple-to-fly sensing platform, which works as a flying tripod for the onboard camera, a high resolution Sony Alpha 7R. The drone can be easily flown to inspect positions close to water or the shore, underside of the bridge, piers and decks. Even the most remote point of a structure can be closely inspected. Professional bridge inspectors with a drone service, use a pre-defined grid method, with various shooting distances and angles, to ensure the entire bridge is inspected properly.

Case study – Drone Bridge Inspection of the Anna-Ebert Bridge

The Anna-Ebert Bridge was inspected by a two man team. Norman Hallermann and Christian Ahrend, as pilot and co-pilot respectively. They were able to survey and inspect the complete bridge within few hours. They flew the UAV / drone about 5 meters distance away from the construction. The AscTec Falcon 8 was also tested for this application over years by the Bauhaus University Weimar, resulting in numerous projects and constructions surveyed and inspected successfully. As a consequence Guido Morgenthal Technologien im Bauwesen (GMTIB) was founded to serve the high demand for UAV- / drone-based structural analysis.

Learn more about services provided by GMTIB:

The Anna-Ebert-Bridge was inspected from a two-man team. Norman Hallermann and Christian Ahrend as pilot and co-pilot were able to survey and inspect the complete bridge within few hours. They flew the UAV / drone in about 5 metres distance to the object. Over two years the Bauhaus University Weimar tested the AscTec Falcon 8 for that application. Numerous constructions have been surveyed and inspected successfully. As a consequence Guido Morgenthal Technologien im Bauwesen has been founded to serve the high demand for UAV- / drone-based structural analysis.

Scope of the bridge inspection:

  • GPS-based mission and flight path planning for an automated inspection and survey of the construction
  • Comprehensive aerial imaging of the structure facades including aerial views with high-resolution images without any interference to the public and flowing traffic
  • Detailed aerial images of 43 individual free standing sculptural elements of the bridge.
  • Documentation of the construction and the decorative elements as the basis for conservation

Results of the drone-based bridge inspection flight:

  • 3D reconstruction of the building as georeferenced 3D point cloud with 1.3 Billion points
  • High-quality orthophotos from all building views with 1 mm/pixel resolution
  • As-built plans of the Northeastern and Southwestern view including individual stones
  • Meshed and textured 3D models of the construction with 240 Millions of polygons
  • True to scale, fast 3D models of all decorative elements with about 10 Million points each: 40 images done in 4 minutes, dense point cloud 34.5 Mio. single points, mesh with 101 Mio. polygons, accuracy: <0.5 mm!
  • Data preparation for the public relations work of the city Magdeburg
  • Deformation monitoring: Data storage for automated detection of geometric changes by exactly reproduced bridge inspection flights in the future.

Drone bridge inspection with waypoint automation

Surface damages like cracks and spalling can only be detected from close distances. Inspectors need to work at the same close distance right at the bridge, which is expensive and frequently dangerous. Often inspectors need support by way of industrial climbers, hubs, scaffolding, crane or boats, to access remote and critical spots. Every structural analysis is thus very time-consuming, and generates significant financial and human costs.A solution for accurate deformation monitoring is possible without high financial resources or human cost. Infrastructures, such as buildings and bridges, can be flown over by a UAV; the waypoint automation flights are exact and reproducible. With an established stable and reproducible pathway, the slightest alterations to a structural integrity can be detected with the UAV.

Obviously the exact order and effort of the bridge inspection will vary depending on the type of bridge being inspected.

Bridge inspection & much more

The AscTec Falcon 8, a civil UAV / drone, is an unmanned measuring instrument – providing high-definition video, stills and thermal imagery data; with these capabilities it could change the game for construction industries. It can be used for diverse drone applications and inspection services from: surveying land in construction planning, onsite documentation, building inspection, frequent monitoring of real estate, or structural inspections for repair and maintenance work, for heritage monument, and energy efficiency control. For construction industries UAVs / drones like the AscTec Falcon 8 are becoming a highly efficient inspection tool with which even the smallest changes can be detected.