ORBIT: Optimized Routing for Bridge Inspection Toolkit. An open-source UAS flight path planning tool for comprehensive bridge inspections under realistic constraints

Abstract. Manual bridge inspections are labour-intensive, hazardous, and costly. While unmanned aerial system (UAS) are promising to facilitate the process, current flight planning tools do not address the unique challenges of complex bridge geometries or GNSS-denied underdeck environments. We present ORBIT, an open-source toolkit for generating optimized waypoint routes specifically designed bridge inspection missions using only minimal prior data. ORBIT generates coordinated waypoint routes for overview and underdeck inspections, maintaining spatial overlap between datasets to facilitate accurate image alignment. This approach also allows the UAS to closely follow bridge side faces at constant offsets, optimizing data acquisition for damage detection tasks. The planning workflow supports integration of commonly available cross-sectional plans or satellite imagery, incorporates flexible safety zones, and exports missions in standard KML and KMZ formats for direct use even with off-the-shelf commercial drones. Field deployments on multiple concrete canal bridges demonstrate that the generated routes provide complete inspection coverage. Underdeck missions were successfully executed using a DJI Mavic 3 Enterprise, relying solely on its onboard IMU when GNSS was unavailable and achieving reliable operation for bridge spans up to 20 meters. By making ORBIT openly available, this work aims to enable safer, more precise, and scalable UAS-based bridge inspection, and to support future research in the field.
https://github.com/ErToBar2/ORBIT