Network Rail

Low adhesion between wheel and rail can be caused by autumn leaf fall, reacting and adhering with the steel, resulting in signals passed at danger, station overruns or in worst cases derailments and collisions. Various methods to remove this layer or increase friction have been developed including water jetting, abrasive cleaning, traction gels and chemical treatments, new interventions are trialled each year. However, representative low friction conditions are difficult to generate repeatedly and measure, as such the efficacy of these interventions remains difficult to establish. Twenty years ago British Rail Research stated “Paradoxically it has been the lack of low adhesion that has hindered the development of low adhesion remedies”. This still remains largely true today. In this paper a method is proposed to form a representative organic layer, by placing powdered leaf material on the railhead and rolling with a vehicle until it has blackened and bonded to the underlying steel. The layers were visually inspected using industry guidelines and their friction was measured using the new Rivelin Rail PRT300 tribometer. The method was found to be capable of reliably producing contamination levels from light to heavy as required for testing by varying the quantity of leaves added. Friction coefficients for medium and heavily contaminated rails were all below 0.05, these would typically be described as ultra-low adhesion. As an illustration of the method, a trial of a new (anonymised) railhead cleaning technique is included in this work as a case study. The layer formation and measurement methodology proposed could be adopted by the wider rail industry to provide a more data-driven approach to understanding friction enhancer and railhead cleaning technology performance, through optimising current treatments and assessing the performance of novel technology.

Summary This study shows the use of Distributed Acoustic Sensing (DAS) to monitor seasonal changes in shear wave velocity (Vs) on a railway embankment in Southern England. Fibre optic cables were installed along a 350m long embankment, and active seismic surveys using hammer impacts were conducted from Aug 2022 to Aug 2023. DAS measurements, correlated with soil moisture and matric suction, showed good agreement between seasonal moisture fluctuations and Vs. During dry periods, Vs values were higher, while wetter conditions resulted in lower values, indicating reduced soil stiffness. The findings demonstrate DAS-based MASW as an effective, high-resolution alternative to traditional geophysical methods to monitor railway embankments.

Over the last 10 years there have been significant developments and improvements in the understanding of railway track bed in the UK and its relationship and impact on track quality, ballast life and maintenance following track renewals.This paper aims to describe the process adopted by Network Rail for track bed investigation and design which offers Network Rail optimum design solutions and value for money from an investigation and construction perspective, balancing design with possession availability to maximise construction output.It also describes innovative investigation and construction techniques that have been developed over the last 5 years maximising the use of rail mounted asset condition data collection systems which run at line speed, allowing targeted investigations and in some case removing the requirements for physical site investigation.It also allows Network Rail to predict sections of track bed which may be affected by line speed increases which would cause the track bed to fail prematurely or, retain its ability to maintain good track geometry post line speed increase.These problems can manifest themselves as stiffness related problems such as critical velocity issues (surface wave velocity, Rayleigh Wave velocity) or, sub-grade erosion resulting in high rates of deterioration in the vertical track geometry.The paper also describes the development and installation process for Enhanced Axial Micropiles to address stiffness related track bed problems whilst leaving the track in-situ a technique which is new to the UK railways.

With the rapid evolution of the wireless networking technologies, various wireless network services emerged and penetrated into all aspects of life. Numerous wireless networking applications, such as smart cities, industrial Internet, and Internet of Vehicles, are developed and deployed around the world. More and more wireless devices are connected to the Internet, forming an enormous Internet of Things (IoT). Especially, in the era of fifth-generation wireless communication (5G), IoT becomes one of the three natively supported scenarios, which will consequently promote the development of IoT-based applications [1]. The forthcoming sixth-generation wireless communication (6G) will bring stronger communication capabilities with more features and will lead to new wireless applications [2]. One can foresee that the wireless networking technology, together with artificial intelligence, big data, cloud computing, will form the cornerstone of the future smart life. While providing extraordinary convenience to connect people and "things," the wireless networks are facing more and more security challenges from adversaries. In this chapter, a security measure that exploits the physical layer characteristics of the transceivers is introduced. The related research progress is reviewed and a representative technique is presented. Some potential research directions are highlighted.

24/7 Sobriety programs largely focus on reducing alcohol consumption among justice-involved individuals whose alcohol use has led them to repeatedly threaten public safety. Participants are ordered to abstain from alcohol use and subject to frequent alcohol testing (e.g., twice daily breathalyzers, remote alcohol monitoring); those testing positive face an immediate sanction, typically a night or two in jail. Unlike drug courts and other forms of coerced substance use disorder treatment, 24/7 does not require participants to enter a treatment program or attend self-help group meetings; however, these approaches are not necessarily mutually exclusive. The empirical evidence suggests that participants largely abstain from heavy drinking while in the program and that 24/7 participation is associated with lower probability of criminal legal involvement and mortality. This evidence is largely based on research in the Great Plains states with large rural populations. Several questions remain about these programs (e.g., optimal program length, possible benefits of incorporating positive incentives, efficacy of different alcohol testing technologies), many of which can best be answered in an experimental setting. In addition to reviewing the existing research on 24/7, this paper highlights additional research questions and ideas for conducting randomized controlled trials with the program, especially in more urban areas.

Research Problem: Families with children travel by car more frequently than any other household type and hence significantly contribute to transport externalities. Lift-sharing is a potential time-effective and convenient means of mitigating these effects. Whilst some research has been conducted on lift-sharing for the school run, there is little research beyond this context, particularly around lift-sharing for children’s activities (e.g., sport). Study Aim: Consequently, the aim of this study was to assess the current prevalence of lift-sharing (for children’s activities and other types of trips) in families with young children, the factors influencing its uptake, the experiences and attitudes of regular lift-sharers, and whether previous literature findings on reciprocity applied in this context to gain a deeper understanding of how and why families participate in activity lift-sharing. Research Design: A mixed-methods approach was applied, comprising (1) a travel survey of 474 families to establish socio-demographic and activity factors that influence lift-share prevalence for activity trips; and (2) 15 semi-structured interviews with parents to further explore how and why families participate in activity lift-sharing. Results: Factors influencing lift-sharing decisions for activity travel were number of cars owned, number of seats in the car, settlement type, income, time of day and location of the activity, number of children attending, parking availability, whether the activity is a sporting activity or not, and number of close friends of the child at the same activity. Salient motivating factors triggering lift-sharing included intentions to reduce chauffeuring and parents wanting their children to socialise. Trust was an initial imperative component of lift-share formation, and attitudes towards reciprocity supported previous literature findings relating to the variability of acceptable reciprocation and the role of fairness.

A boundary element model for the transmission of vibration over the surface of multi-layered ground has been developed. The model represents two dimensional layers over an elastic half-space. A harmonic load acts over a nite width on the surface. For layers of uniform thickness the results are compared with those from an exact semi-analytical model. Experimental evidence is presented on the thickness of layers and the imponance of this parameter in determining the propagation characteristics. The boundary element model allows the solution of problems with non-uniform layers. An example showing the effects of sloping layers is given.