Geodesy in context - the slogan of our company does not only mean performing pure geodetic work but also includes overlapping into other fields and efforts to solve projects in a broader context. This comprehensive approach brings significant benefits not only to clients but also to other professionals involved in the projects. One example of such work is the implementation of a modem route.
What is a modem route and what is it used for?
A modem route provides communication between the elements in a station and between stations for safe and proper control of the operation of the railway line. This communication must be independent of the environment and is implemented using communication and fibre optic cables. The fibre optic cables may be of different types:
The use of these types of cables marked OK is subject, according to the type documentation of the railway administration, to precise rules for their use and in terms of their location (position in or outside the station) and several fibers (72, 48, 24 ...).
Implementation process
Within the framework of the project, we carried out fieldwork consisting of laying out and surveying a cable route (kyneta) of 4.2 km in length. The modem route was part of a larger project for which documentation had to be prepared. It consisted of our completed construction and six other related constructions. The total length of all constructions for the Jihlava - Krahulov connection was 39.2 km.
Substrate analysis
The documents provided by the client were of varying ages and quality. Our first step was to analyze this data and decide on its usability. The documentation from 2016-2022 was mostly satisfactory, while older materials often lacked important information. Some of the documentation was even only in 2D without elevations, did not contain any descriptive information about the origin of the points, anddid without a technical report giving other necessary information. In these cases, we had to resort to locating the existing cuneiform by so-called "whistling". This method proved to be problematic at nodal points, for example at crossings or stations, where due to the induction of the electromagnetic field into the parallel lines, there was a loss (indication) of signal into these parallel lines and this affected the interpretation of the route.
Installation of cables and chambers
New cable chambers ("Romold" and "Okos") were installed along the route for the fiber optic cable termination.
A total of 49 cable chambers and 168 HDPE pipe joints were built to serve as protectors for the fiber optic cables. The colors of the HDPE tubes were carefully checked to match the documentation, although there were discrepancies due to faulty workmanship or poorly prepared documents, see photos. This included, of course, detailed alignment from the existing railway track centreline or other identifiable elements of the superstructure.
Documentation
The project included the creation of detailed documentation, which included the creation of a cable plan book. This represents the documentation of the actual design from the cable manager's perspective. It includes, of course, an introductory sheet with a technical report, a clear situation of the cable route with the marking of joints (see photos), cut-outs, chambers, cable reserves, a schematic pipe run, a diagram of the DOK, TOK routing in detail (see photos), i.e. with the splitting, a diagram of the location of the optical switchboard in the rack, floor plans of the rooms with the location of the cabinets and the technical specifications of the cable, etc.
What to add in conclusion?
The project has shown that surveying alone is not enough. The key to success is to combine expertise from different areas and the proof of this is the successful submission of the documentation.
We would like to thank the VYG and ČL branches for their diligent work, which was essential for the successful implementation of this project.
Ing. Pavel Hladik
