The article presents the basic parameters given in the EN 16730 standard for Under Sleeper Pads (USP) used in ballasted railway tracks. Also discussed are the IRS 70713-1 recommendations of the International Union of Railways (UIC), which are based on many years of research on the application of USP in railway tracks. Further parts of the article present a detailed analysis of specimens of USP produced from recycled tire rubber (SBR crumb rubber bound with a polyurethane binder). Upon comparing the results of static and dynamic bedding modulus tests with the UIC recommendations, it was noted that the analyzed USP should be classified among soft USP types – which are used for the reduction of ground-borne noise and vibrations affecting structures in the vicinity of the track. Going beyond the requirements of the EN 16730 standard, additional laboratory tests of viscoelastic properties were performed using a Dynamic Mechanical Analyzer (DMA) device, focusing on the vibration damping potential of elastomeric materials. The determined characteristics included characteristic temperatures in complex stiffness modulus tests, the master curve of complex stiffness modulus, and dissipation properties as a function of temperature. The paper classifies a documented recycled-SBR under-sleeper pad against EN 16730 and IRS 70713-1 and reports complementary DMA measurements (characteristic temperatures, a 20°C master curve of the complex modulus, and cyclic dissipation) that are not required by the standard. The aim is to provide material-level input for the soft-USP class, not to propose a new mix design.
The article presents a systematic analysis of the hydraulic response of a circular culvert under discharge escalation scenarios using three-dimensional computational fluid dynamics (CFD) modeling and comparison with conventional HY-8 design-level predictions. Three discharge conditions were considered: the design flow Q₁ = 6.70 m³/s and escalated flows Q₂ = 10.05 m³/s = 1.5Q₁ and Q₃ = 13.40 m³/s = 2.0Q₁. Turbulence-model sensitivity (SST k–ω, Realizable k–ε, and RNG k–ε) was examined to quantify model-induced uncertainty in outlet-velocity prediction. Results indicate that outlet velocity increases approximately linearly with discharge, reaching 7.42-7.51 m/s under the highest flow condition, while deviations among the turbulence models remain below approximately 1.5%. Headwater depth increased from 1.94 m at Q₁ to 3.68 m at Q₃. CFD and HY-8 headwater depths agreed closely across all three scenarios: 1.94 versus 1.93 m at Q₁, 2.68 versus 2.67 m at Q₂, and 3.68 versus 3.69 m at Q₃, corresponding to relative CFD-HY-8 differences of +0.52%, +0.37%, and −0.27%, respectively. HY-8 is therefore used here as a design-level benchmark rather than as independent validation of local CFD fields. Non-dimensional analysis based on HW/D, a diameter-based velocity scaling parameter V / √gD, and Reynolds number indicates that discharge escalation primarily amplifies upstream headwater submergence. Although conveyance capacity remains hydraulically adequate, elevated outlet velocities substantially increase downstream scour potential. The findings support hydraulic safety assessment and outlet-protection design under intensified discharge conditions.
Differences between computed and measured bridge deflections are frequently observed during proof load tests and can lead to conservative or inconsistent decisions in serviceability assessment and load rating. The article focuses on railway filler-beam decks and uses their proof load response as the basis for experimental validation of alternative FE modelling assumptions. Proof load tests performed on five single-span filler-beam railway bridges on the E30/C-E30 corridor are used to compare measured midspan deflections with finite element predictions obtained from three composite-action assumptions: A) full composite action of the concrete slab in compression and tension, B) partial composite action consistent with UIC recommendations and compatible with the general provisions of Eurocode 4, and C) compression-only composite action. The results demonstrate that models adopting full composite action provide the closest agreement with measured deflections, while conservative cracked-section assumptions significantly overestimate deflection. The study also quantifies the influence of secondary stiffness contributors, in particular service walkway slab, on both the magnitude and transverse distribution of deflections, and confirms that the observed trends are consistent across the analysed bridge set.
The paper investigates the feasibility of incorporating materials obtained from the sorting and mechanical processing of waste into unbound mixtures intended for road embankment construction. The objective of the study was to evaluate the effect of adding shredded waste from groups 19 12 10/12 on the mechanical performance of unbound mixtures designed for road embankments and to determine the maximum waste content that satisfies the applicable technical requirements. The experimental programme comprised laboratory tests to determine compaction characteristics, California Bearing Ratio (CBR), coefficient of permeability and internal friction angle of soil/aggregate mixtures containing different proportions of shredded waste. The applicability and limitations of these materials were analysed with reference to current technical specifications and international experience. The results demonstrate that shredded waste from groups 19 12 12/10 can be successfully incorporated into materials used for road embankment construction, providing significant economic, social and environmental benefits.
The article examined how styrene-butadiene-styrene (SBS) copolymer type, polymer content, and base bitumen composition affect the chemical response, as assessed by FTIR spectroscopy, of polymer-modified bitumens (PMB) to short-term technological overheating. Two paving-grade bitumens, 160/220 and 50/70, differing in colloidal instability index, were modified with four commercial SBS copolymers at 3 and 8 wt.%. Part of each binder was additionally conditioned at 240°C for 1 h to simulate accidental overheating during production or storage. Binders were analysed by Fourier-transform infrared spectroscopy (FTIR), supported by thermogravimetric analysis (TGA) of neat SBS copolymers and differential scanning calorimetry (DSC) of non-overheated PMBs. The SBS index depended mainly on polymer content, but its response to overheating was strongly influenced by SBS type and base bitumen composition. TGA showed neat SBS copolymers did not undergo major bulk decomposition at 240°C under nitrogen, while DSC on non-overheated PMBs showed strong effects of base bitumen composition on phase organization. Overall, PMB response to overheating is governed mainly by polymer-bitumen compatibility, SBS architecture, and phase structure, not by copolymer thermal decomposition.
