Reconstruction of the railway yards and platforms in the railway station Čachovice is part of the pilot projects of the use of BIM in the design of railway structures. It is the second building on the section Nymburk - Mladá Boleslav. BIM project for Railway Administration, s.o. was prepared by SUDOP Praha a.s. Our company was on the site as the main surveyor of the contractor. In the pilot project, of course, it is the interest of all to fine-tune all the details for both the project and control side. As one of the control mechanisms we chose to use the latest methods of data collection. These were mainly imaging using unmanned aerial vehicles (so-called drones) and ground laser scans. Aerial photography always took place after the completion of the specified stages of work. From each picture was created a holistic orthophoto map of the whole construction site and thus a record of key moments of construction. An important advantage is especially the speed of data collection, where it is possible to record the whole large area within one day without having to select the recorded objects. Another part of the inspection was also a surface model based on these images, which captures not only the position of objects but also their height. In this way, 10 stages were carried out from the beginning of the construction to its completion.
Finally, a control laser survey was performed. Again, high speed data collection was used along with their accuracy and density. It is also possible to record, for example, both the position and rotation of the lighting lamps and the precise design of the actual bridge structure.
The results of both methods were used to create the documentation of the actual implementation in two ways. The first is to use it as a primary source of information for the BIM model in the form of point clouds. The second is the orthophoto map as a tool for solving documentary conflicts that arose after evaluating the focus of individual elements.
Author: Ing. Ondřej Kočí