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Scour is a complex phenomenon and one of the most frequent causes of riverine bridge failures. Detecting scouring effects is a complex geotechnical/structural/hydraulic engineering challenge. Incorporating more risk-based approaches into scour assessment frameworks may allow for enhancements over current processes which remain reliant on visual inspection to detect bridge scour. Scour detection and monitoring is inherently a ‘damage detection’ task. A wide range of technologies for scour monitoring are available which may partially replace or supplement visual inspection activities. Recently, a new rating framework has been presented to assist engineers to assess the relative merits of different sensor technology options on scour-prone bridges. In this paper, the development of this framework is reviewed and compared with other scour rating frameworks; suggestions for future development and calibration are proposed.

Bridges are important lifelines linking communities and their collapse due to flood events can result in severe social and economic impacts for communities. Estimation of maximum bridge scour depth is important for determining effective mitigation and adaptation procedures. HEC-18 is a well-established methodology to calculate scour depth. However, it isalso often reported to yield conservative estimates of maximum scour depth in various publications. This paper presents a simple sensitivity study to assess the key inputs that affect the computation of maximum scour depth using the HEC-18 framework. The parameter ranges used in this analysis are sourced from an openly accessible database from the United StatesGeological Survey (USGS). In this study, HEC-18 is assessed against field measurements. The primary aim of this research is to study the impact of each key input parameter on HEC-18 estimates of maximum scour depth estimates.

The visual inspection of bridges is a major undertaking for asset owners and operators. In the UK, visual inspections require inspectors to visit bridges on-site and often at night and in unfavourable weather conditions. Therefore, it would be beneficial to move some of the visual inspection process off-site. This paper studies whether the defect classification aspects of the inspection process could be conducted remotely using photographs. This study examines the defect ratings assigned by ten survey participants who were tasked with examining photographs from visual inspections of ten UK bridges. The survey results were compared with the results from the general inspections previously carried out for the bridges in question. From this dataset, the differences in the ratings given and the extent to which defects are missed were examined. The results show that a higher number of defects were identified for a given bridge by the remote inspectors. Statistical analysis shows that aggregated defects rated by off-site inspectors tend to be more severe and of a higher priority rating compared to those from the on site inspectors. The results also indicate that there is closer agreement between on-site and off-site inspectors for defects of a higher severity rating.

Hydraulic filling is used for land reclamation work and/or to increase the ground level of low-lyingareas. Changes in gradation properties of the hydraulic fill is to be expected during hydraulic filling process which comprises dredging, transportation, deposition, and compaction. These changes in gradation can influence the hydraulic conductivity (permeability coefficient) of the resulting hydraulic fill mass. This hydraulic conductivity is further exacerbated by potential ponding of the transient remnant sea water within the constructed fill mass and its extent in relation to location of points of discharge and the groundwater regime of the area. This paper examines the effect of change in gradation on the hydraulic fill mass coefficient of permeability, using the grading entropy framework to investigate changes in the coefficient of permeability of the hydraulic fill mass. The paper also examines the possibility of applying the gradation entropy framework to assess the liquefaction potential of sand fill mixtures ‘after deposition’ and the in-situ granular foundation strata due to seismic events.

A-priori estimates of maximum scour depth are important for bridge engineers, managers and owners. HEC-18 is an established method which uses empirical equations to estimate bridge scour. This paper applies the HEC-18 methodology to compute maximum scour depth for 936 bridge piers for which field scour depth measurements are available from an online database from the United States Geological Survey (USGS). The results are in general agreement with past research efforts which suggest that the HEC-18 methodology tends to overestimate maximum bridge pier scour depth. The database is also categorized into various sub-sets to study the effect of different particle sizes and devices used to measure scour in the field.

Rainfall-triggered landslides are increasingly a concern in rapidly urbanising areas around the globe. Assessing the stability of slopes is important for geotechnical engineers and planners working in these regions. Saturated hydraulic conductivity is key parameter for assessing the hydrological drivers of slope instability. This paper presents a recent citizen-science case study in Quito, Ecuador, in which saturated hydraulic conductivity measurements were taken in the field on a fine-grained volcanic sediment, often referred to as cangahua, were obtained as part of the Tomorrow’s Cities project on urban multi-hazards and disaster risk management. These data are then used along with a recent soil database of Quito soils (Quito/GEO-299) and other locally obtained soil data and the Combined Hydrology And Stability Model (CHASM) to assess the stability of slopes in a hillside community in South Quito. The paper focuses on the variability of key slope stability parameters, including saturated hydraulic conductivity to assess the plausible ranges of behaviour for slopes in this area.

The liquid limit (LL) of a fine-grained soil is widely understood as relating to the water content (w) at which the soil has a small remolded undrained shear strength (cu) (e.g. Wroth & Wood 1978). When the fall-cone apparatus is used to measure LL (i.e., 〖LL〗_FC), this can be shown to be true based on plasticity theory (Koumoto & Houlsby, 2001). Whilst when measured using the Casagrande-cup apparatus (i.e., 〖LL〗_cup) there is a small variation in cu at the LL (i.e., cu LL(cup)) of soils having different levels of plasticity owing to dissimilar soil bulk density (ρ) at their LL states, as demonstrated by Haigh (2012). For a given Casagrande-cup apparatus type, the 〖LL〗_cup actually relates to a constant specific strength (i.e., cu LL(cup)/ρ) magnitude (Haigh, 2012). However, the strength value at LL is not explicitly stated and thus, whilst it is demonstrable that the strength magnitude at LL is approximately constant, the LL w itself (i.e., 〖LL〗_FC and 〖LL〗_cup) is defined by the method prescribed by a testing standard used for obtaining it (e.g., ASTM D4318-17e1, 2018; BS EN ISO 17892-12:2018+A1:2021 2021), in addition to the specifics of the equipment design which may vary between countries (Haigh, 2016).

Bridge scour is a major cause of bridge collapse worldwide. Various approaches are available to estimate levels of scouring due to hydraulic loading. Such scour depth assessment methodologies typically employ a series of empirical and semi-empirical equations to estimate scour around a bridge element. This workexamines three such methodologies, namely the Hydraulic Engineering Circular Number 18 method (HEC-18) 4th edition, the HEC-18 5th edition method and the Texas A&M University method (TAMU). The paper compares the results from these three calculation methods with field data from 23 bridge piers (eight bridges) located in the State of Maine (USA). The paper investigates the levels of conservatism in the estimates of scour depth calculated using these three methodologies. All three approaches tend to give conservative estimates of maximum scour depth, especially for low values of scour depth, when compared to the field dataset examined in this paper.

Bridges are important infrastructure assets that are vital for the connectivity of communities. Visual inspections remain a key method for bridge condition monitoring. However, visual inspections are often considered to be highly subjective and therefore alternative technologies are often proposed as a means of replacing or enhancing current visual inspection practices. This paper presents the results of a survey which aims to document the emerging trends for future visual inspection practice related to bridges. The implementation of new technological solutions has the potential to improve the quality of inspection data, reduce the safety risks posed to visual inspectors by moving more of the process off-site and improve the quantification of the rate of change in condition. The survey covers two key topics: (i) Emerging data capture methods and (ii) Emerging data analysis methods. Emerging data capture methods include: use of uncrewed vehicles, 360° cameras, photogrammetry, laser scanners, point cloud systems, and Interferometric Synthetic Aperture Radar (InSar). Emerging data analysis methods include: remote inspection, augmented reality and virtual reality, digital image correlation, artificial intelligence, Big Data and the Internet of Things. The survey concludes with a detailed discussion on the opportunities and barriers to implementation of the reviewed technologies and approaches.