The present paper is dedicated to the analysis of under sleeper pads (USP), which are resilient elements used in ballasted track systems as vibration isolators. Four types of USP are considered. The authors present the results of laboratory tests, which are then used as input values for the finite element (FE) and mechanical model of the structure. A special focus is put on the description of an original four-degree-of-freedom (4DoF) mechanical model of the system that includes a fractional rheological model of USP. Using the proposed approaches, the dynamic characteristics of under sleeper pads are determined, and conclusions on vibration isolation effectiveness are drawn.

Pedestrian fatality rate in Poland of 30 deaths per year per million population was the second highest among the EU countries in 2013. In the years 2007-2013 some 13% of pedestrian fatalities and 26% of injuries occurred at unsignalized pedestrian crossings where pedestrians should theoretically be safe. The paper presents results of research project MOBIS which was aimed to develop surrogate safety measures based on detection of dangerous situations or near-accidents. Within the project, pedestrian and vehicle traffic was recorded at four pedestrian crossings in Warsaw and Wrocław, for a period of approximately 2 months per crossing. Motion trajectories of vehicles and pedestrians were determined and certain parameters describing the pedestrian-vehicle encounters calculated. The average number of such encounters was over 1000 per day in both Warsaw and Wrocław. Dedicated video and data analysis algorithms were used to extract interactions that met certain criteria. To this end the following parameters were used: velocity profiles of pedestrians and vehicles, minimum distance between the participants, deceleration during braking, etc. These variables were used to develop surrogate safety indicators for pedestrian-vehicle encounters. A classification of encounters based on the characteristics of pedestrian-vehicle interaction is also proposed. Within the project certain solutions for increasing pedestrian safety at road crossings were installed and evaluated. These included speed cushions and flashing lights warning the drivers about pedestrian presence that were either mounted on traffic poles or embedded in the road surface. The evaluation of these solutions will be based on surrogate safety measures developed in the MOBIS project

The paper presents essential static and dynamic properties characterizing resilient mats for vibration isolation of railway tracks. The attention was focused on under-ballast mats and slab-track mats used in the construction of railways. Referring to this type of mats, selected test procedures for determining the values of parameters describing static and dynamic characteristics were described. Basic classification of vibration isolation mats was presented in the paper. Moreover, the essential functional and operation features related to various types of mats were given. Some theoretical aspects concerning viscoelastic dynamic modelling of resilient track elements were also outlined. In order to characterize requirements and methodology of research for resilient mats in railway tracks, German Standards [1–3] were used herein

The present paper is aimed at the analysis of under ballast mats (UBM) which are used in ballasted track structures as vibration isolators and to protect the ballast layer against fast degradation. The mats were tested in the laboratory and afterwards a novel 4-DoF mechanical model of the track structure with UBM was developed. The novelty of this study consists in the comparison of two testing procedures: a procedure based on the popular German standard DIN 45673-5 and a new European standard EN 17282, released in October 2020. Major discrepancies were demonstrated in the determined values of the static and dynamic characteristics using both approaches—especially in reference to the mats with higher stiffness.

The present paper focuses on laboratory tests of fatigue strength of prototype under ballast mats (UBMs), carried out according to the procedure described in the new European standard EN 17282, which was released in October 2020. The mineral wool-based mat revealed significant differences in the values of static and dynamic characteristics, measured before and after the fatigue tests. The elastomeric mats based on recycled materials (SBR granulate and fibers) turned out to have had sufficient durability and effectiveness of protection against vibration caused by railway traffic. The values of static and dynamic bedding moduli, determined before and after the fatigue tests, were used to develop a viscoelastic rheological model of the vibration isolator with the use of fractional derivatives. Using this original model of the ballasted track system with four degrees of freedom, a significant influence of cyclic loading on the level of vibration suppression (insertion loss factor) was demonstrated. The analytical model confirmed that the mats with variations of bedding moduli exceeding 10% should not be used as resilient elements.