## 2 Methods for Measuring Dynamic Response  
Geodetic methods are non-invasive methods that can be used to monitor various responses of structures. The authors of [50] conclude that global navigation satellite system (GNSS) methods, light detection and ranging (LiDAR) technology and synthetic aperture radar (SAR) interferometry can be used for construction monitoring to determine the dynamic response and study structure deformations [51; 52; 53; 54; 55; 56; 57]. The use of these approaches is not adequately explored in the available literature. From our previous research on the use of geodetic methods for determining dynamic responses, we found that the described methods are quite unreliable, as they do not give uniform results, the sampling frequency is too low, the height component is unreliable and the accuracy of the results is questionable. Among the geodetic non-invasive methods described, the RTS method is generally used for this type of monitoring.  
Recently, the automated acquisition and processing of spatial data on deformations has been the subject of numerous studies. Detecting structural deformations and determining their shape and dimensions are complex processes that require an interdisciplinary approach [58; 59; 60; 61].  
In our study, we focused on monitoring the dynamic response of concrete railway sleepers replacing wooden sleepers. The study was carried out with a practical example for which we determined the response of the threshold under the load of different train compositions and simulated the dynamic responses in the laboratory of our faculty. The purpose of the study was to investigate how we can determine the responses of a structure in the most ideal, cost-effective, fast and reliable way, even in places where electronic high-precision methods are out of the question due to ranges, inaccessibility and safety. In order to compare the results for the dynamic response obtained with different methods, the results of the geodetic measurements were additionally processed and, with the help of FFT analysis, the frequency, dominant frequency and amplitude were obtained.  
The devices we typically use for non-contact monitoring have high price ranges and do not usually offer a wide range of applications. Recently, vibration monitoring devices of sufficient quality to perform vibration monitoring and analysis, with a graphical interface capable of storing, processing and displaying the input data from the sensors in real time, have also been used to convert signals from the time domain to the frequency domain. An example of the use of such a device is given in [62], where it demonstrated very good accuracy. The analysis of vibration monitoring results can also include statistical modelling based on multi-binary rules [63]. Choosing the right measurement technique is nowadays crucial to obtain accurate results. One very precise and efficient monitoring process is based on the integration of non-contact measuring systems and simultaneous monitoring with contact measuring instruments. Contact sensors vary in size and weight. Some of them are quite difficult to install. Non-contact sensors are relatively small and light, making them easier and cheaper to install, which speeds up monitoring. In general, non-contact methods are less accurate but not by much. The LDV method used in this study is a typical example of non-contact monitoring, as it generates a point cloud or voxel as the most basic data format. In this way, a huge amount of data can be obtained in a very short time, which is the primary advantage of non-contact monitoring methods.