See the railway viaducts from above

The Přerov-Bohumín railway line, nowadays also referred to as line 271, was an important transport structure already in the 19th century. At that time, it belonged to the famous company of the privileged Northern Railway of Emperor Ferdinand, and beautiful period railway bridges were built on it. The Hranice and Jezernice viaducts were even declared a cultural monument of the Czech Republic in 2007.

Let's take a look at the individual objects separately.
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The Jezernice viaduct actually consists of 2 originally brick bridges that were built in the middle of the 19th-century side by side. It rises above the Jezernice stream valley between the Lipník nad Bečvou and Drahotuše bus stops and is almost 427 m long. A total of 42 major and minor arches have been completely reconstructed and the viaduct was awarded the 2001 Bridge Work of the Year award by the Ministry of Transport of the Czech Republic. Frost-resistant bricks were used and the reinforced concrete arch was anchored into the brick arches with a metal net.

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The Hranice viaducts refer to three parallel railway bridges that arch over the Velička River near the Hranice na Moravě railway station. The first two brick structures are interconnected by concrete slabs that cover the gaps between them, where the joined piers touch. The third structure, i.e. the concrete bridge, is connected to them by a footbridge in the place of the gaps.
Our colleagues Ondřej Kočí and Ondřej Filip first surveyed both viaducts in the field from a height and then Radim Holub processed them as 3D visualizations. What devices were used and why are 3D visualizations created? Read the comments directly from our specialists.
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• What instruments did you use for the flying?
  Ondřej Kočí: "At the Jezernický viaduct we took off with a DJI Matrice M300 drone equipped with a DJI P1 35 mm camera. In the case of Hranický, again with a DJI Phantom 4 PRO. For scanning purposes, we chose Trimble SX10, X7 in both cases."
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• How long did the whole event take you in the field? And did you encounter any complications?
  Ondřej Kočí: "Scanning the objects and surroundings took about 2 days of work and the raid itself took up to 30 minutes per site. As the work was carried out outside the growing season and in ideal weather, we did not encounter any significant complications."
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• Why did you choose this type of data collection and the above-mentioned instruments?
  Ondřej Kočí: "This method, where the data is collected quickly, including all details, is very little dependent on the amount of detail required compared to conventional measurements. In addition, the evaluation takes place in the office and it is possible to retrospectively add elements as required. I would also like to add that the new Trimble X12 super-powerful scanner was also tested during the scanning process, as we are constantly adding the latest technology to our surveying stock."
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• How was the 3D visualization of the viaducts created? And why was the game engine chosen?
  Radim Holub: "I created the 3D visualization using a game engine, a software framework that concentrates on general functions used in computer games. The functionality of the application was programmed using C# language and was converted according to WebGL standards to run in a web interface. The application is multiplatform and programmed in such a way that each user can adjust the graphical complexity according to his/her computer performance and customize the user settings (mouse sensitivity, etc.). At the same time, the application was created for both desktop and the aforementioned web environment. The standards of game development were followed in the development of the application."
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• What are the advantages of a game engine?
  Radim Holub: "Game engines provide a wider range of possibilities. With their help it is possible to achieve a photorealistic perception, they allow animation of the movement of vegetation and other not only natural elements. They can also work very well with PBR materials, simulation of real physics, and other VFX or particle effects. Game engines, therefore, provide a robust set of tools and functionalities that are suitable for creating complex 3D applications."
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• How can such 3D visualizations be used in practice? Where can they help?
  Radim Holub: "This is important when planning new buildings, their expansion or reconstruction, and similar projects. Thanks to the three-dimensional representation and detailed modeling is possible to get a more realistic view of the future result.
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  Another way to grasp 3D visualizations is the so-called digital repository. Given buildings contain some historical value, 3D visualizations, and applications can capture their appearance at a certain point in time. This digital record can be used for reconstruction, documentation or conservation.
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  A third way to work with visualizations is their role as a guide. Their photorealistic form makes them an effective tool for providing guides and instructional material in various fields (they can, for example, increase tourism in a given place, etc.)."

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The route between Lipník nad Bečvou and Přerov was originally a single-track line. In the middle of the 20th century it was converted into a double-track line and today it is also fully electrified. It belongs to the so-called II. transit railway corridor, which is the main long-distance railway line between Breclav and Petrovice u Karviné.

Take a look at the important and historically significant sections on this route and come and fly over the two viaducts.

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Technical documents and answers. Ondřej Kočí, Ondřej Filip and Bc. Radim Holub

Text: Mgr. Lucie Kmochová

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