The development of reliable methods for measuring deflections as trains pass has enabled valuable insights into railway track behaviour to be gained. This is especially useful for problem areas such as transitions from normal ground onto hard substructures and complex track geometries such as switches and crossings.To date, much of the research on transition zone behaviour has focussed on transitions associated with underbridges and other substructures. Switches and crossings have received some attention and level crossings generally very little. This paper describes and discusses the behaviour of a transition onto a level crossing in the south of England, UK. Measurements are presented from both trackside and on-train instruments. It is found that at this crossing, maintenance constraints have resulted in a group of unsupported or hanging sleepers on the approach to the crossing; and that this fault is not effectively rectified by tamping. Comparisons are also made between the way the fault shows up in measurements from trains of the loaded track profile and data from trackside measurements.

Extreme weather causes substantial adverse socio-economic impacts by damaging and disrupting the infrastructure services that underpin modern society. Globally, $2.5tn a year is spent on infrastructure which is typically designed to last decades, over which period projected changes in the climate will modify infrastructure performance. A systems approach has been developed to assess risks across all infrastructure sectors to guide national policy making and adaptation investment. The method analyses diverse evidence of climate risks and adaptation actions, to assess the urgency and extent of adaptation required. Application to the UK shows that despite recent adaptation efforts, risks to infrastructure outweigh opportunities. Flooding is the greatest risk to all infrastructure sectors: even if the Paris Agreement to limit global warming to 2°C is achieved, the number of users reliant on electricity infrastructure at risk of flooding would double, while a 4°C rise could triple UK flood damage. Other risks are significant, for example 5% and 20% of river catchments would be unable to meet water demand with 2°C and 4°C global warming respectively. Increased interdependence between infrastructure systems, especially from energy and information and communication technology (ICT), are amplifying risks, but adaptation action is limited by lack of clear responsibilities. A programme to build national capability is urgently required to improve infrastructure risk assessment.This article is part of the theme issue ‘Advances in risk assessment for climate change adaptation policy’.

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Trackside monitoring of railways provides useful data for understanding the condition and mechanical behaviour of railway track, prior research has shown that railway track performance varies significantly along its length, primarily owing to changing support conditions. Understanding the changing performance along track offers the potential for improved track design and maintenance. Different technologies are used to investigate this. For example, inertial sensors, or high-speed filming with digital image correlation (DIC) for track deflection, and traditional strain gauges for loads. The latter usually rely on in-situ calibration. These techniques are suitable for measurements at discrete locations along the track length but are not suited to measuring performance variability even along a few hundred meters of a railway line. This paper investigates the use of a recently developed sensing system known as distributed acoustic sensor (DAS) that uses optical fibres. This method has the potential to be used over very long lengths of track; offers high sample rates; and has a gauge length and spatial resolution suitable for investigating the load-deflection behaviour of the track. This study presents DAS optical fibre strain measurements from a study site and presents novel methods for determining the rail deflection and the load per sleeper end. The DAS results are compared with point location measurements using a traditional strain gauge and deflections determined using imaging and DIC. The DAS system offers reliable distributed strain measurement that convert to estimates of track deflection and load with the potential for continuous spatial and temporal coverage over significant lengths of track.

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