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This manuscript presents findings from an ongoing research study at Oklahoma State University studying different factors that affect vertical tie reaction forces in ballasted railroad tracks. A combined approach involving field instrumentation and numerical modeling has been adopted for this purpose. Measurements of tie reactions can indicate the load distribution patterns and quality of vertical support along a track. Locations where tie support conditions are not adequate can develop geometry defects, ultimately leading to component failure. Three different approaches are adopted in this study to measure the forces being transmitted through the rail-tie interface; this is equal to the tie reaction force. The field instrumentation effort validates an alternative method to measure forces at the rail-tie interface using rail-mounted strain gauges. Results from this approach are compared to two other conventional methods of force measurement, i.e. through the use of load cells (LC), and an instrumented tie plate (ITP). A validated 3-dimensional Finite Element (FE) model is used to support the field-observed trends, and explain any observed discrepancy. Parametric analyses using the FE model identify different factors that can contribute to the rail-tie interaction force, thus affecting the instrumentation results. The strain gauge-based approach, using the concept of differential shear strain measurement, has been established as a suitable method for tie reaction force measurement. Exact measurement of the tie reaction force can be ensured through proper installation of the strain gauges, away from possible boundary effects.

Ballast fouling is a problematic track condition that can lead to inadequate ballast performance. Prioritizing remediation of fouled ballast sites is difficult because no relationship between ballast fouling and track performance exists and fouled ballast performance depends on the amount, grain-size, type, plasticity, and moisture content of the fouling material. This paper provides results of an international industry survey on fouled ballast definitions, parameters, limits/standards, and laboratory test results to aid development of a procedure for quantitatively assessing ballast fouling and assessing the ability to: transmit applied train loads to the subgrade, allow drainage, and maintain proper track geometry as required under §213.103.

Acid and metalliferous drainage (AMD) impacts may be a cause of significant long term environmental liabilities, as evidenced on many historic mine sites containing legacy AMD issues worldwide. These historical precedents have led to AMD being recognised as a key closure risk by industry and regulators, which in turn has driven progressive advances in geochemical assessment and management in recent times. Many AMD risks on a typical mine site are based on mineral waste management strategy and practice. By association, mine planning and scheduling may therefore have a significant bearing on the potential for AMD related closure liabilities. Despite this, the assessment of AMD risk is often packaged into the environmental approvals and management process, which is often not directly connected with the mine planning and scheduling process. Consequently, AMD assessments and management plans are frequently progressed by an approvals team that is often somewhat disconnected from the mine planning and scheduling team. Subsequently, AMD management measures may be conceived after the scheduling process has moved into a more advanced and less flexible phase. Sometimes, this may be the result of a lack of early coordination and/or budget leading to a lack of hard geochemical data with which to begin classifying potentially acid forming material. Using an integrated approach to managing closure risk can be achieved via a method of assessment utilising 3D geochemical block modelling that can operate concurrently with (or within) the mine planning and scheduling process from early in the mine planning process. A more integrated approach sees AMD assessment and management being advanced concurrently with resource modelling to optimise results and minimise risk. Three case studies are presented in this paper where an integrated approach was used for conceptual closure planning through the environmental approvals stage. A further case study is presented where an integrated approach was taken to develop a mine plan. The application of this approach has so far proven encouraging.

One of the more critical failure modes of concrete crossties in North America is the degradation of the concrete surface at the crosstie rail seat, also known as rail seat deterioration (RSD). Loss of material beneath the rail can lead to wide gage, cant deficiency, reduced clamping force of the fastening system, and an increased risk of rail rollover. Previous research conducted at the University of Illinois at Urbana–Champaign (UIUC) identified five primary failure mechanisms associated with RSD: abrasion, crushing, freeze–thaw damage, hydroabrasive erosion, and hydraulic pressure cracking. Because the magnitude and distribution of load applied to the rail seat affects four of these five failure mechanisms, effectively addressing RSD requires an understanding of the factors affecting rail seat load distribution. As part of a larger study aimed at improving concrete crossties and fastening systems, UIUC researchers are attempting to characterize the loading environment at the rail seat by using matrix-based tactile surface sensors (MBTSS). This instrumentation technology has been implemented in both laboratory and field environments and has provided valuable insight into the distribution of a single load over consecutive crossties. This paper focuses on the analysis of data gathered from MBTSS experiments designed to explore the effect of manufactured RSD on the load distribution and pressure magnitude at the rail seat. The knowledge gained from these experiments will be integrated with associated research conducted at UIUC to form the framework for a mechanistic design approach for concrete crossties and fastening systems.