Abstract
In order to determine the relative or absolute railway track and foundation deformation, ground based laser scanning technology is utilised in this study to attain a precise 3D track reference. Located at the University of Nottingham’s Innovation Park, the newly built Nottingham Geospatial Building, where the Nottingham Geospatial Institute is based, has a roof laboratory that has unique testing facilities. This includes a mini railway track of 120 m in length and other long term monitoring monuments. A test was performed to precisely determine the ground truth location of the railway track using a phase based laser scanner for the formation of a standard reference. A real three dimensional mesh of the laser scanning data forms the basis for the line extraction. The compactly supported radial basis function (CS-RBF) was employed to determine the track features based on a 3D mesh approach. To verify the achievable accuracy of laser scanning technology, ground truth points measured with geodetic methods are compared with the extracted sample points and the results are presented in this paper.
Highlights
Due to the rapid increase in the mileage of high speed railways in China in the recent years, a challenging task for the railway authorities is how to precisely monitor the health conditions of the foundations and track
The procedure can be divided into three sections: Firstly, an approximating 3D mesh from the laser scan data uses an adaptive compactly supported radial basis function (CS-RBF) algorithm, which approaches the real world features precisely and avoids the misconnection of irrelevant points that is evident in a two-dimensional TIN (Figure 3) [1]; secondly, the triangles are searched for the feature points by a multistep vertex normal manipulation [6]; and thirdly, the final procedure is to connect the line segments with the excellent Berkeley natural boundary detector to form the complete track [5]
The experiment has proved that railway track extraction based on laser scanning could be a timely and efficient approach for the determination of highly accurate railway tracks
Summary
Due to the rapid increase in the mileage of high speed railways in China in the recent years, a challenging task for the railway authorities is how to precisely monitor the health conditions of the foundations and track. Deformations can be estimated through comparing the established standard reference with the measurements gathered from regular field observations. In this case using a dedicated monitoring platform with high precision dynamic positioning and orientation capacity is an ideal solution for the determination of the micro changes of the railway track and foundations. The main component of this laboratory includes a pinched obround shaped mini railway track of 120m long and 184.15mm gauge This laboratory has been constructed for dynamic positioning system research and testing (Figure 1). To estimate the achievable accuracy of laser scanning technology, ground truth points measured with other geodetic location methods are compared with the extracted sample points and the results are presented in the paper. It is anticipated that similar procedures could be employed in the monitoring of the real-world high speed railway tracks
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