This thesis explores the use of Axle Box Accelerations (ABA) in passenger trains as a means to monitor and assess the structural health of railway turnouts, particularly the crossings. The increasing demand for higher capacity, speed, and axle loads, coupled with reduced maintenance time, has put a strain on the reliability of these sensitive components. The study focuses on the fixed crossing, a vulnerable component due to its discontinuity that can cause large impact forces leading to potential failure and disruptions.

The research aims to develop an assessment method to determine crossing health using ABA measurements from two retrofitted intercity trains. The crossing, formed by the wing rails and a crossing nose, presents a discontinuity that disturbs wheel motion and generates impact forces. The study acknowledges the challenges related to data quality, quantity, and processing due to the random nature of measurements and conditions. Despite these challenges, the research leverages the Law of Large Numbers and the Central Limit Theorem to overcome frequency-limited measurements.

The proposed assessment method is validated against geometry metrics derived from train-borne laser measurements. However, the current approach does not establish a reliable relationship between the impact angle and wear levels, making it unsuitable for monitoring wear levels of crossings. Nevertheless, a strong correlation was found between the kinematic wheel dip angle, mean and standard deviation of vertical impact, indicating that a larger mean or standard deviation suggests a more degraded vertical geometry. This finding is in agreement with prior research based on wayside measurements and underscores the potential of in-service passenger train ABA for assessing the structural health of turnout crossings.

Asphalt concrete is the most used material in road construction. Analysing the behaviour and properties of this material is vital for modern day society. Currently, this is mostly done in labs using actual asphalt mixtures. However, this is a very expensive and time consuming process. An upcoming alternative approach is the use of computational models. The finite (FEM) and discrete element methods (DEM) have been used in the past, but both of these have shown significant disadvantages regarding the modelling of discrete particle movement and shape, respectively. An upcoming alternative is the use of physics engines, such as Bullet Physics, to model porous media. This method can have substantial benefits in terms of costs and research time. Also, phenomena can be visualised that cannot easily be observed in experiments.

This research focusses on the utility of Bullet Physics for modelling hot asphalt compaction. Therefore, a complex contact model is implemented which can describe the contact forces of the bituminous mixture. The superpave gyratory compaction process is digitally modelled. The model has been programmed in PyBullet, an open source physics engine, programmable in Python. A parametric study has been performed, which reveals the significance of certain properties, which cannot easily be investigated during laboratory compaction.

Bullet Physics was not initially designed for scientific research in the field of structural engineering. Therefore, alterations are needed to make the software usable. The implementation of a complex contact model is challenging. Although the Burgers’ contact forces can be correctly described, it proves difficult to implement custom contact forces directly in PyBullet. Two attempts have been made. In the case of a custom integration scheme, the computation time proved too long to be applicable for large scale simulations. In case of a direct implementation in Bullet Physics with the application of external forces, instability occurs. The only correct way to implement a custom contact model is by altering the source code.

During the simulations with a simpler contact model, substantial improvements of digital simulations over actual experiments are presented. The consistency proves far better than the prescribed minimum. The influence of inertia and friction can be assessed. It turns out that inertia, as well as the friction of the mould, can be disregarded. Another phenomenon that can be clearly illustrated is the revolving of aggregates inside the mould. Further analysis has shown that the average contact area depends on degradation, but in a typical asphalt mixture does not depend on the size of the individual elements, and could rather be treated as a constant. Further analysis shows that Bullet Physics is incredibly efficient, thus yielding the possibility of performing large scale simulations within reasonable time.

This research aims to improve the sustainability of Dutch prestressed concrete railway sleepers. Approximately 100.000 to 200.000 sleepers are used every year, corresponding to 12.000 to 24.000 tonnes of concrete. This will be done by replacing cement with an alkali-activated binder. The cement industry is responsible for approximately 5 to 7% of the global CO2 emission, whereas the alkali-activated binder uses no cement. Instead, by-products will take over the role of cement in concrete, activated by high pH alkalies. This research can be subdivided into four parts: Deciding the requirements, designing for the mechanical properties, determining the durability properties and conducting a Life Cycle Analysis (LCA). The main requirements follow the product specification of the railway infrastructure manager ProRail. Some requirements on manufacturability follow from a market consult. Ground granulated blast furnace slag is used as a precursor due to its availability in the Netherlands, unlike other potential candidates. An iterative mix design procedure is conducted to come to three mixes, meeting the requirements for the fresh concrete and the mechanical properties. The three mixes differ based on the binder content and activator dosage. Nineteen different mixes are designed, of which the final three meet all the mechanical and manufacturability requirements. These three mixes are subjected to tests to determine non-required mechanical properties, such as the tensile strength or the material’s elastic modulus. Finally, the durability of the newly designed alkali-activated slag concrete is assessed. Results show the designed concretemeets the requirements for fresh and hardened concrete. The results of the other mechanical properties are similar or better to the concrete mixes used nowadays to produce sleepers. However, not all requirements on durability are met. Due to the unavailability of certain test conditions, a direct result cannot be given. Therefore, the three durability properties are assessed by comparing the results of this research with results from the literature. The comparison for electrical resistivity shows an excellent behaviour, better compared to similar OPC concretes and on par with CEM III/B concrete types. The alkali-activated binder demonstrates less damage under a freeze-thaw attack with de-icing salts than other alkali-activated concretes but still fails to meet the requirement set by ProRail. The accelerated carbonation test indicates a similar carbonation resistance compared to other alkali-activated concrete types but a lower resistance compared to similar concrete. More research is necessary to investigate these properties further. The environmental impact of the concrete used to produce a sleeper is reduced by 34 to 68%compared to a CEM III/B or OPC binder, respectively. Taking into account the global warming potential only, these numbers increase to 75 to 90% respectively. The total environmental impact of a complete sleeper, including steel and plastic components, is lowered by 12 to 35%. This is explained by the fact that the steel and plastic components contribute 75% to the environmental cost, and improving the cost of these components is beyond this research’s scope. This research shows a significant potential to improve the sustainability of concrete structural elements by replacing the cement binder with an alkali-activated binder. This binder is capable of meeting the mechanical requirements, shows good workability. The compressive strength values are comparable to high strength concrete. Further research has to be conducted in the fields of behaviour under carbonation and freeze-thaw attacks. With these results and conclusions, this research has attributes to realizing more sustainable railway sleepers using an alkali-activated binder.

Transport by rail has taken Europe by storm ever since their introduction in the 19th century. Developments in the past 150 years have led to the construction, deconstruction and reconstruction of various rail connections. In the Netherlands, a small number of lines in its more rural parts no longer have any standard passenger services and are now in use as museum lines, with purposes more focused on tourism and the preservation of history.

This report analyses the possibilities of the reactivation of the Hoorn-Medemblik museum railway line through the use of light rail vehicles. The line is currently only used for a historic tram service as a touristic attraction.

Aspects this report covers are an analysis of the area in which the railway is located and a provisional program of requirements and desires. A legal, infrastructural and traction related framework in which the basic principles and limitations of a revived passenger service are considered. The report specifies and recommends basic operational details on the basis of this.

This MSc thesis research has the objective to empirically determine the perceived stochastic nature of the deceleration regimes and to determine the impact it has on infrastructure occupation within the network corridor. This research expands on the data-driven reconstruction model to estimate the speed profiles of realised train runs developed by N. Besinovic et al., calling it the 'Deceleraton Reconstruction' (DR) model. This model elaborates on the deceleration regimes of the speed profiles in a more dynamic and generalised manner to provide a more detailed description of the realised deceleration behaviour, through introducing the concept of sub-regimes to describe the deceleration regimes and the concept of a non-uniform braking rate in the braking regimes. This research expands on the number of data sources used for location tracking of the realised train runs and introduces the concept of 'Data Fusion' in which the different sources of location tracking are combined in order to provide a more reliable and more detailed input for the DR model. The results of the empirical and comparative analysis, provide interesting insights to the correlations between the departure delays, realised running times and deceleration loss time performance, and provides insights to the impact the deceleration behaviour has on infrastructure occupation. The DR model provides interesting results regarding the quality and detail of the estimated deceleration behaviour (e.g. braking rate, deceleration regime profile) and compares these in relation to the nominal characteristics used in timetabling tools and simulation models.

Railway maintenance is currently planned according to a fixed schedule, mostly of one year. This is usually not optimal when considering the cost of maintenance, of possessions and of failure. However, an approach that minimizes the sum of these costs was not yet available. This paper presents a statistical analysis method and an optimization problem that aims to solve this problem. It is applied to fictitious problems and a realistic test case.