This article presents the authors’ comprehensive evaluation of the application of specific foam thermal insulation materials, namely expanded polystyrene (EPS) and extruded polystyrene (XPS), within railway substructures. The assessment extends to real-world conditions on the tracks of Slovak Railways (ŽSR), which share substantial similarities with other countries’ railway networks. The assessment of structural composition and material selection considers these technical aspects, while technological feasibility and the environmental implications associated with material production, delivery, and incorporation into railway construction do not. Additionally, the thermal insulation materials’ qualities are compared against conventional railway substructure materials. In these conventional setups, the thermal insulation layer often incorporates crushed aggregate of specified fractions and parameters in line with legislative standards. This article complements previous research conducted at the University of Žilina, focusing on the application of various thermal insulation materials within railway substructures. These materials were both experimentally tested (scale of 1:1) and numerically modelled, with results previously published by the authors. The published works detail the utilisation of diverse thermal insulation materials in railway substructures, primarily evaluating two crucial technical parameters: the protection of the subgrade surface against adverse effects of frost and, secondarily, their impact on the deformation resistance of the railway substructure.

The paper investigates whether foam glass could reduce the structural thickness of the protection layer in the construction of the railway track (saving of natural materials – crushed aggregate) and, at the same time, also provide sufficient thermal protection of the frost-susceptible subgrade surface. It also discusses whether the incorporation of foam glass would have a relevant effect on the increase of the deformation resistance of the railway track structure at the level of the sub-ballast upper surface. Following these assumptions, the paper presents the results of experimental measurements of the deformation resistance of the modified structural composition of the sub-ballast layers (with an embedded foam glass layer) and their comparison with the results determined on a structure with a standard composition of the sub-ballast layers (crushed aggregate sub-ballast layer/protective layer). Also, numerical and mathematical analysis of the influence of the built-in thermal insulation foam glass layer on the reduction of the structural thickness of the protective crushed aggregate layer in terms of the effect of climatic factors is conducted in the paper. The mathematical model, developed by the research, provides the possibility of continuous monitoring of the change in the railway track structure freezing depending on climatic characteristics. Keyword : railway track, sub-ballast layers, thermal insulation layers, foam glass, static load tests, climatic factors

When a new vehicle is being developed, the parameters of the electric motor, battery modules, and control algorithms have a significant impact on its dynamic characteristics. This paper presents a method of determining the dynamic characteristics of a three-wheeled tilting vehicle created by AKO team. In order to achieve this, the acceleration values in theoretical calculations were determined and were verified by experimental field tests using a three-wheeled vehicle prototype. Theoretical calculations include the determination of speed, dynamic factor, air resistance, and traction force. The theoretical calculation of the above-mentioned dynamic factors also involves the experimental determination of the drag coefficient, which was performed in a wind tunnel using a scaled-down (1:16) three-wheeled vehicle model. Field tests were conducted to determine acceleration data using two accelerometers, one of which was used for the synchronization of the calculated acceleration data with experimentally obtained acceleration data. Obtained data from very sensitive accelerometer were filtered using a Butterworth second-order low-pass filter. Results show compliance between the calculated and measured accelerations, which means that theoretical calculations were verified by experimental measurements.

Adverse climatic conditions, particularly excessive water and frost, necessitate the design of thick protective sub-ballast layers when dealing with frost-susceptible subgrade surfaces, especially when using standard natural materials (crushed aggregate or gravel–sand). Given the current preference for conserving natural construction materials and promoting sustainable development in the dimensioning of sub-ballast layers, it is advisable to incorporate various thermal insulation, composite, or suitable recycled materials in their design. Therefore, the paper analyses the impact of incorporating different thermal insulation materials (including extruded polystyrene, Liapor, Liapor concrete, and composite foam concrete) into sub-ballast layers. As part of the experimental research, these modified sub-ballast layers were constructed on a real scale in the outdoor environment of the University of Žilina (UNIZA) campus. They were subsequently compared in terms of their thermal resistance to climatic loads. The research results demonstrate that extruded polystyrene provides the optimal thermal insulation effect in modified sub-ballast layers, which was subsequently used in the numerical modelling of railway track structure freezing under different climatic loads.

The present study explores the effect of incorrect tire mounting on vehicle braking performance with a specific focus on its interaction with the Anti-Lock Braking System (ABS). Experimental testing was conducted utilizing a passenger vehicle under controlled conditions according to ISO 21994. Two tire configurations were studied: a complying axle-wise configuration and a non-compliant asymmetric arrangement with the same tires mounted longitudinally on each side of the vehicle. ABS was switched on and off throughout the braking testing. The dynamics of the vehicle and its brake parameters were recorded and analyzed using nonlinear statistical modelling. The obtained coefficients of determination of the suggested nonlinear model were in the range of 0.8265 to 0.9938 and showed a satisfactory agreement with the experimental data. Chow-type statistical testing revealed significant differences across all tire designs and ABS operational modes tested (p < 0.001). Ljung–Box test indicated the lateral acceleration signals were significantly temporally dependent. The results indicate that the incorrect asymmetric tire mounting has a negative influence on the braking dynamics and this effect is more significant when the ABS is turned off. While ABS mitigates these effects to some degree, we still observe statistically significant disparities in performance. The results give empirically validated proof of the need for proper tire installation for the preservation of braking performance and vehicle safety and contribute to a better understanding of tire–road interaction and braking dynamics under asymmetric tire configurations.

When a new vehicle is being created or developed, many technical parameters that affect dynamic characteristics must be investigated not only on a theoretical level, but also by natural experiments. Especially one of the most important characteristics for a vehicle that can tilt is tire–road contact, which later helps to calculate and simulate different driving conditions in different driving scenarios, applying internal and external forces. This paper presents a unique construction of a three-wheeled tilting vehicle prototype, tire–road contact determination, and evaluation of vehicle behaviour using the Pacejka tire model. To achieve this, the tire and road surface area were investigated. Using the computed method, experimentally determined contact areas were refined and compared with the actual measured. Determined tire–road contact areas were evaluated by applying dynamic external forces for further investigation. Selected a scenario to predict the behavior of a three-wheeled tilting vehicle and the force distribution during tilting, then determined certain vehicle parameters in the static position (load distribution, tire–road contact areas). The inclusion of asymmetric front-left and front-right tire loads under tilt resulted in observable differences in force distribution. The inner front tire unloaded while the outer tire gained load, introducing asymmetry in both lateral and longitudinal forces. This behaviour was not captured in the symmetric model.