Blom have completed an aerial LiDAR survey for VR Track Oy, the leading rail constructor in Finland. Covering approximately 91 km, the survey ran along the main rail line spanning the Finnish towns of Lielahti and Kokemäki, and would be run for the alliance of VR Track and the Finnish Traffic Authority.
VR Track required digital ortho photos and DTMs (digital terrain models) for the planning of maintenance necessary to improve safety and traffic on the track and approached Blom due to their extensive experience in this area.
The DTM project was managed by Pasi Kråknäs, the leading survey expert at VR Track. Having formerly had experience of working with Blom, and the use of TopEye LiDAR technology in similar projects, Pasi commented “In my experience, TopEye technology produces very accurate and reliable laser data for this kind of modeling.”
Flying for the LiDAR capture began in late autumn, when vegetation had already disappeared but before snow covered the ground. Weather conditions are typically very challenging during this period but, due to the efficiency of TopEye LiDAR, data collection was successfully completed on 1st November 2011.
LiDAR was flown by helicopter at a flying height of 400 m, generating a point cloud of 10 points/m2, and digital images with ground resolution better than 5 cm GSD (Ground Sample Distance). VR Track completed required control surveys for matching and calibration. LiDAR data and images were processed by Blom Sweden and quality control completed using Blom’s in-house software; TASQ.
A DTM covering a 100 m wide corridor, digital ortho photos and a height model were handed to the planning team at VR Track as the final project deliverables. Parts of the laser data were delivered to other consultants to necessitate additional vectoring work. Pasi Kråknäs reported that final results were in accordance to technical requirements, the schedule according to the plan and the project was completed within budget. “I am sure that VR Track will continue co-operation with Blom in future projects” he summarizes.