Cascading effects are high-impact, low-probability phenomena that have caused catastrophic impacts in various chemical and process plants around the world. With the increasing trend of cyberattacks targeting critical infrastructures, there is a concern that accidents caused by cyberattacks may trigger cascading effects in these facilities. In this study, we have demonstrated that the implementation of network segmentation to ICS networks to improve its robustness against the risk of cyberattack-related cascading effects. A risk-based methodology is developed to investigate and evaluate the robustness of design alternatives. The risk-based methodology also incorporates a risk assessment method based on Bayesian networks for cascading effects modeling. Further, this thesis also presents some design guidelines for developing robust networks segmentation designs, which includes the application of a graph-theoretic approach that enables early identification of the severity of cascading effects in network design alternatives. The risk-based methodology and the design guidelines are applied to a case study in which the efficacy of the approaches are demonstrated. The outcome of the risk-based methodology offers an alternative risk mitigation technique that can be considered in the risk management process.

The Covid-19 pandemic has outlined the creativeness of each country in the definition of the most appropriate public health management strategies to curb the spread of the SARS-CoV-2 virus, ranging from total lockdowns to trusting in people’s common sense to act properly. Several non-pharmaceutical health interventions have nationally been issued either on a voluntary bases or required by law. Maintaining 1.5 m distance and wearing protective face masks provide two respective examples. Proximity contact-tracing apps have furthermore been launched at a national scale to alleviate the pressure on the overburdened testing capabilities by means of automatic contact-tracing. Also the Dutch Ministry of Health launched its CoronaMelder on October 10, 2020. However, its efficacy is being questioned with the consideration of its instigated user behaviour. More specifically, it is being hypothesized that the CoronaMelder app instigates users to comply less with the issued non-pharmaceutical health interventions, thereby countering their expected beneficial effects in curbing the spread of the virus. An explorative sequential design provided the answer, where literature review findings were combined to conceptualize the effect of the app on attitude, perception and eventually behaviour. Structural equation modelling performed on data collected through an online survey (N=776) outlined the lack of causality from the CoronaMelder to behaviour and as such, compensatory behaviour was excluded. Moreover, it was found that older and higher educated people were more prone to install the app, similarly to people at risk and those who had previously contracted the virus. Eventually these results were placed in the context of behaviourally-informed politics to assess the management of nationally launched digital contact-tracing apps.

Over the last 30 years, different technical and governmental developments have taken place in the Dutch hazardous materials pipeline infrastructure. These have changed the utilization and governance of the system, with the transport of natural gas being one of the most important during this timeframe. Due to the danger of the transported material, the integrity of the system is crucial for its operation and performance. But with trends like liberalization, aging, and the energy transition, it raises the question whether this integrity is maintained. Also with many researchers analyzing either technical or governmental development, the combination has not yet been studied. The following main research question was formulated: What insights do we take when reflecting on the influence of technical and institutional developments on the integrity of the natural gas system in the Netherlands? With the combination of desk research, interviews, and content analysis, the alignment between the technical and the governmental developments will be analyzed with the alignment perspective of Künneke, Groenewegen & Mènard. This information is then used to see if possible misalignments correspond to integrity perspective changes and issues of the infrastructure. Resulting eventually in insights into possible institutional or regulation deviations from what the system needed at that point in time.

Numerous structural failure incidents have occurred in the past years. It was found that current methods, such as NEN 2767, fall short in guaranteeing the structural safety of existing buildings. Although structural failure incidents infrequently result in casualties, there are also social and economic consequences that impact both building user as owner. Interviewed asset managers have noted that the current lack of insight into a building’s structural condition often leads to preventable maintenance and repair costs, and safety risks. When coupled with changes in the outdoor and built environment, such as a focus of continuity in use, these risks become increasingly challenging for owners to manage. To ensure structural safety of significant public buildings within CC3, mandatory assessment via NTA 8790 must be performed. However, this method is exclusively tailored to CC3 buildings and only considers potential casualties as risk consequences. This strategy neglects CC2 buildings and other potential consequences, exposing them to elevated risks due to a lack of insight into their structural conditions. All the asset managers interviewed for this study, all managing CC2 buildings, reported these issues. The goal of this thesis is to develop an efficient and effective assessment method to evaluate existing consequence class two buildings on structural safety to prevent incidents with structural failures. As a start (CC2) building typologies within the Netherlands were examined to determine the typologies for which the method should be optimised. Subsequently, structural failure incidents were analysed, resulting in a list of common causes that should be considered during the assessment. However, due to limited data availability, expert interviews and general literature this list is not exhaustive but rather an initial attempt. It can serve as a focus during the assessment but should not be solely relied upon. Finally, existing assessment methods were evaluated based on trustworthiness, effectiveness and efficiency. The findings from this evaluation have been incorporated into the development of an efficient and effective assessment process, which is described in the document. The assessment process developed in this study was validated by applying it to two existing buildings, leading to the following conclusions. The assessment process developed in this study has proven effective in evaluating the structural safety of CC2 buildings, thereby preventing incidents relating to structural failures. While the necessity for comprehensive risk analyses does impact the time required for the assessment, these analyses have been optimised to concentrate on the most critical aspects. Along with other efficiency-enhancing aspects, it presents an efficient method within the parameters of effectivity and trustworthiness. However, as revealed during validation, not all deficiencies can be detected using this method. There will always be hidden deficiencies that remain undetected and assessors are made aware of this limitation. Despite this constraint, the method provides an efficient and effective evaluation of the structural safety of existing buildings.