Subgrade mapping on selected D3 lines Brno

We helped to map the background on selected lines with simplified traffic management

In the Czech railway operation on lines operated by the Railway Administration, the D3 conveyor is a designation for conveyor stations on lines with simplified traffic management according to the SŽ D3 regulation (so-called D3 lines).

In the spring of this year, we carried out a contract for the mapping of six line sections in two stages. The scope of the surveyed railway stations was approximately 5 kilometres and the scope of the broad lines (sections between railway stations) was approximately 33 kilometres. The surveys involved the surveying of position and elevation - detailed mapping of the railway superstructure, substructure, terrain, roads, all fixed objects, utilities - railway broad lines and railway stations.

Surveying work in such activities is very diverse: from checking the railway point field and mutual visibility of individual points through locating property boundary features (landmarks, stones), finding all registered culverts and elements through the actual surveying to processing in a 3D graphic environment.

In terms of type, all types of lines were involved: from simple clear lines and stations to more complex bridges to sections in deep cuts or embankments. In some places, the height differences between the track and the surrounding area were greater than 20 metres, often with rock walls. In order to be able to survey in such difficult terrain, we had to survey the railway line centreline and the immediate surroundings separately, with the help of additional polygon sequences on one and the other side of the embankment or notch. In addition, the property boundary was not always right at the foot of the railway body, but in some places even 5 to 10 metres from the foot of the slope. More than a third of the territory was in wooded and sometimes almost impenetrable areas. There were also two viaducts on one of the track sections - these were surveyed in 3D and evaluated using so-called point clouds. This technology uses instruments called scanners to collect data - which are robotic total stations capable of recording up to 26,600 points per second within a given section.

Of course, photo-documentation of the 50-meter line step and photo-documentation of culverts and bridges were also included. Office work was carried out after and during the completion of all fieldwork. As it was a railway line, the mapping and documentation were carried out in accordance with the regulations of the Measures for Surveying Objects of the Railway Transport Route; Large Scale Special Purpose Railway Map; Large Scale Special Purpose Railway Map, etc.

When surveying, one discovers many interesting views and gets to places one would not normally get to. Within the scope of work duties and with the necessary training, of course. Except for places intended for the public, access to the road is prohibited. In addition to the four railway stations and the viaducts already mentioned, we also went through the tunnel under the D1 motorway and took a look at the steel structure of the bridge, which spans nearly 250 meters over the valley above the Oslava River in Velké Meziříčí. The Vysočina and Brno branches successfully participated in the contract.

Ing. Pavel Hladík

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