Monthly Archive: October 2016

GIS 3D feature extraction and modelling for railways using LIDAR technology

With the global drive towards Building Information Modelling (BIM) compliance gathering pace, we have seen an increased requirement for highly accurate and detailed geospatial data within utilities and engineering projects. This has resulted in a corresponding increase in the application of LIDAR technology within these sectors.

In particular, railways have a wide range of complex and critical assets that extend across the rail network. LiDAR survey point cloud data and feature extraction has become an accurate and effective means of modelling, sharing, managing and storing large asset information databases of this sort.

The primary benefit of LIDAR technology lies in its ability to capture assets in 3D. For rail networks, train mounted LIDAR equipment is on the increase because it allows accurate, dense point clouds to be acquired along with the RGB images from the in-cabin video. Having worked on a number of such high-profile projects, SBL has built up a large team of LIDAR modellers and analysts who can process and extract the full range of railway features and assets.

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Fig 1 A wire frame model of a sample gantry derived from LIDAR point clouds

Railway assets include electrical network and equipment, telecommunication network and equipment, tracks and related features, signal systems and station assets. The advantage of deriving 3 dimensional data from LIDAR point clouds is that it will be accurate to a millimetre level. All the peripheral equipment can be modelled in a 3D environment as well. Along the tunnel sections of the network LiDAR is the only technology that can provide comprehensive, highly accurate information on assets.

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Fig 2 station and its component assets as captured from LIDAR point clouds

Mapping to high detail and then rendering in various model platforms is the key to usage of LIDAR based capturing of railway assets. All features within the corridor width of the tracks can be captured to the same very high detail. Stations have innumerable assets components but all these components can be captured effectively using LIDAR point clouds. The creation of a real world situation using 3D models has attracted the attention and approval of many of SBL’s stakeholders and partners. Our LIDAR analysts have achieved these impressive results through 3D wire frame and surface modelling. These models were created and delivered in global GIS formats such as .dgn or .dwg or gml.

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Fig.3 A tunnel section captured from point clouds

This kind of LIDAR technology based railway mapping will benefit different disciplines in different ways. This database will act a pre indicator for drivers and is of great help in their training. For construction engineers it is a monitoring mechanism. For design engineers it the only information provide kinematics of the entire system. For maintenance and operation teams it is a database where they can pinpoint hot spots where repairs are required allowing ground staff to be sent directly to those locations. Using this database a virtual railway stations and tracks can be created for various applications. Overall asset and facilities management will be greatly improved with such a 3-dimensional database.