Mobile Laser Scanning Technology in Road Depression Measurements

This research paper describes applicability of mobile laser scanning in road depression measurements. The research was commissioned by the Finnish Transport Agency and performed by Destia Ltd. The applicability was researched by examining accuracy, precision, and repeatability of the laser scanning technology. Two about one kilometre long road segments near Porvoo, Finland, were chosen for test sites. Both of them were measured twice with two different laser scanning devices, Trimble MX8 and Riegl VMX-450. Then through a modelling process, 3D surface models were produced from the targets. Also a reference model was made with a levelling instrument from both of the road segments. by comparing these models, the accuracy of the models z-coordinates and longitudinal slopes was examined. Results show that mobile laser scanning has clear promise in road depression measurements. For example, both of the devices used can achieve an average z-accuracy close to zero with about 10 mm dispersion. This could be adequate enough in some cases. It is also possible to improve the accuracy by developing the surveying method. Furthermore, repeatability showed promising results. Some further research and definitions have to be made, although the results were very promising already at this point.