Competition in rail transport: Methodology to evaluate economic impact of new trains on track

Performance that a railway should provide users, in a perspective of market competition for new passenger and freight services, requires the infrastructure manager to a particular focus on processes of rail track degradation generated by traffic during seasonal weather conditions. In particular the study of the distress evolution over time, taking into account rutting and fatigue processes in track formation, provides the indicator to forecast the service life and, therefore, to plan its maintenance. This paper deals with a method to assess the railway structural distress produced by traffic loads and to calculate maintenance work costs. In Europe, liberalization of the railway sector results in increasing traffic load due to new competitors. Depending on the forecast distress evolution in the service life and on the budget available, the maintenance plan to keep the railway infrastructure to the desired level of service may be defined. © 2014 Taylor & Francis Group

Analysis of Vibration Measurements on Moving Trains

The development in society means that infrastructure like ballasted railway systems is facing challenges due to requests for a increased number of high-speed trains and heavier freight trains. This implies that ballasted railways get an increased impact from larger dynamic loads. The question is how the ballasted railways are today affected by dynamic loading and how will an increase in train speed and weight change the soil behavior within the railway embankment. A method of investigating soil behavior is via geophysical measurements. Accelerometers are commonly used for vibration measurements and by installing them on trains, measurements are possible to perform for complete railway sections. The knowledge of Eigen frequencies for various track components and soil layers are essential when considering frequency analysis of accelerometer measurements. Specifically, this means that the analysis is about detecting resonance of different components. From the actual case study, a good correlation is obtained between the expected Eigen frequencies and the measurement results. Thus, an assessment of the dynamic loadings influences on various soil layers and ballast has been possible to perform. Resonance of a soil layer means that the particles will be rearranged and degraded. For the case when saturated soil layers are subjected to resonance a phenomenon called liquefaction can occur if the pore pressures increases to the level were soil layers lose their effective stresses. Therefore, the most critical finding in this study is liquefaction because it leads to a loss in bearing capacity followed by settlements. Old railway tracks where little or no information exists of the soil conditions are the most suitable areas were this measurement and analysis method is of special use. Consequently, conventional borehole sampling can be reduced.ISBN för värdpublikation: 978-981-15-0449-5, 978-981-15-0450-1</p

Assessing ballast cleaning as a rehabilitation method for railway masonry arch bridges by dynamic load tests

Dynamic load testing has become a common practice for condition assessment of masonry arch bridges and lays the foundation for their rehabilitation procedures; however, additional dynamic testing after rehabilitation is rare. Carrying out dynamic load tests before and after rehabilitation programs produces valuable results with regard to the structural changes of the bridge. This paper tries to assess the effects of ballast cleaning on the performance of railway masonry arch bridges by conducting dynamic load tests before and after the rehabilitation procedure. To do so, a 70-year-old masonry arch bridge is instrumented with deflection meters and accelerometers. Dynamic load tests are carried out before and after ballast cleaning and results are compared. According to the test results, vertical deflections of different spots on the bridge remain the same, with a deviation of less than 5%. On the other hand, vibrations on the structure are reduced significantly. On average, vibration levels are reduced by 35% in different spots of the structure.</p