# Modelling of Evenness of Runways as an Element of Sustainable Airport Maintenance
## 2 Methods for Measuring the Evenness of Airport Runways  
Geodetic methods are non-invasive and allow for accurate inspection of on the surface [33]. The authors of [33] conclude that accurate monitoring and prediction of runway condition are the main elements of developing measurement models, such as global navigation satellite system (GNSS) methods and light detection and ranging (LiDAR) technology and synthetic aperture radar (SAR) interferometry, to study runway deformations (i.e., deformations on the surface) [34; 35; 36; 37; 38; 39; 40; 41]. The use of these approaches has not been adequately explored in the accessible literature. Existing runway condition monitoring models are intended for runway skid resistance analysis. Geodetic methods are excluded from existing research, as they are not concerned with runway deformation detection. However, the application of geodetic methods allows the detection of deformations on the surface of the runway.  
Detecting deformations and determining their shape and dimensions are complex processes that require an interdisciplinary approach [42; 43; 44; 45; 46]. Recently, automated acquisition and processing of spatial data on road and runway deformations has been the subject of much research [47; 48; 49; 50; 51; 52; 53].  
In particular, this research focuses on the interpretation and analysis of road and runway images-runway surface modelling based on measurement field data. The development of algorithms for the automatic detection or extraction of deformations from these images, as well as the determination of the dimensions and classification of the deformations are common to previous work. Investigations into the use of geodetic measurement methods in the determination of vertical deviations and the detection of deformations on the surface of runways (as well as the prediction of the formation of new deformations) have not yet been sufficiently carried out or cannot be found in the accessible literature.  
In the present study, the evenness and deformations of runways were detected using geodetic methods. To record the vertical deviations on the runway, a vehicle was constructed on which the geodetic sensors were placed. The measurement was performed with geodetic sensors such as a robotic total station (RTS) and GNSS technology, which are placed on a special vehicle that allows such measurement. The measurement was performed using geodetic equipment such as the technology of the robotic total station RTS and GNSS technology: We had a 360\({}^{\circ}\) prism and a GNSS receiver installed on a specially designed unsprung vehicle. In the article [51; 52], we described a detailed data capture with geodetic equipment. The determination of the position of deformations was carried out based on the established geodetic network, which provides a geometric basis. The relative positions of the trajectory were determined according to the geodetic (null) network. The creation of the geodetic network is a complex process in which the rules of geodetic network planning must be followed. Data management and processing must be controlled, corrections to the measured quantities must be made, and a suitable levelling method must be used.