Paolo Trucco

A Bayesian Belief Network modelling of organisational factors in risk analysis : A case study in maritime transportation

The paper presents an innovative approach to integrate Human and Organisational Factors (HOF) into risk analysis. The approach has been developed and applied to a case study in the maritime industry, but it can also be utilised in other sectors. A Bayesian Belief Network (BBN) has been developed to model the Maritime Transport System (MTS), by taking into account its different actors (i.e., ship-owner, shipyard, port and regulator) and their mutual influences. The latter have been modelled by means of a set of dependent variables whose combinations express the relevant functions performed by each actor. The BBN model of the MTS has been used in a case study for the quantification of HOF in the risk analysis carried out at the preliminary design stage of High Speed Craft (HSC). The study has focused on a collision in open sea hazard carried out by means of an original method of integration of a Fault Tree Analysis (FTA) of technical elements with a BBN model of the influences of organisational functions and regulations, as suggested by the International Maritime Organisations (IMO) Guidelines for Formal Safety Assessment (FSA). The approach has allowed the identification of probabilistic correlations between the basic events of a collision accident and the BBN model of the operational and organisational conditions. The linkage can be exploited in different ways, especially to support identification and evaluation of risk control options also at the organisational level. Conditional probabilities for the BBN have been estimated by means of experts’ judgments, collected from an international panel of different European countries. Finally, a sensitivity analysis has been carried out over the model to identify configurations of the MTS leading to a significant reduction of accident probability during the operation of the HSC.

Dynamic functional modelling of vulnerability and interoperability of Critical Infrastructures

The paper describes a new integrated formalism for the dynamic functional modelling of vulnerability and interoperability of Critical Infrastructures at regional level. The model assesses the propagation of impacts in terms of disservice due to a wide set of threats. The disservice can be propagated within the same infrastructure or to other CIs by means of the interdependence model, which is able to represent physical, cybernetic, geographic as well as logical interdependencies and also the shift of the demand between two infrastructures that can provide the same or fully/partially replaceable service. The model is dynamic, since both the impact of the specific threat on a generic infrastructure node and the inoperability functions are time-dependent. A pilot study has been carried in the metropolitan area of the province of Milan, considering the Critical Infrastructures referred to the transportation system.

Modelling and assessment of dependent performance shaping factors through Analytic Network Process

Despite continuous progresses in research and applications, one of the major weaknesses of current HRA methods dwells in their limited capability of modelling the mutual influences between performance shaping factors (PSFs). Indeed at least two types of dependencies between PSFs can be defined: (i) dependency between the states of the PSFs; (ii) dependency between the influences (impacts) of the PSFs on the human performance. This paper introduces a method, based on Analytic Network Process (ANP), for the quantification of the latter, where the overall contribution of each PSF (weight) to the human error probability (HEP) is eventually returned. The core of the method is the modelling process, articulated into two steps: firstly, a qualitative network of dependencies between PSFs is identified, then, the importance of each PSF is quantitatively assessed using ANP. The model allows to distinguish two components of the PSF influence: direct influence that is the influence that the considered PSF is able to express by itself, notwithstanding the presence of other PSFs and indirect influence that is the incremental influence of the considered PSF through its influence on other PSFs. A case study in Air Traffic Control is presented where the proposed approach is integrated into the cognitive simulator PROCOS. The results demonstrated a significant modification of the influence of PSFs over the operator performance when dependencies are taken into account, underlining the importance of considering not only the possible correlation between the states of PSFs but also their mutual dependency in affecting human performance in complex systems.

Eco-efficiency for sustainable manufacturing: an extended environmental costing method

The opportunity of improving production sustainability through waste minimisation is getting more and more interesting because of remarkable waste generation and the contribution to increase the productivity of natural resources. The article is intended to propose an environmental costing method to enable a proper analysis of the flows of products, by-products and wastes produced by a whole production plant or simply by a section of this plant, in order to properly prioritise a list of likely interventions and to make better decisions to head for higher level of eco-efficiency, hence sustainability. The proposed method origins from a general activity-based environmental costing (ABEC) and, unlike traditional ABEC, considers as cost objects not only the expected products, but also by-products and wastes as in the material flow cost accounting (ISO 14051). Thanks to detail given by the proposed method, it is actually possible to go back to the sources of inefficiency of the process and to simulate the impact of likely eco-efficiency interventions in a what/if approach. Results from a case study of an Italian manufacturing company are finally provided and discussed.

Risk analysis of underground infrastructures in urban areas

Abstract The paper presents an integrated approach for vulnerability and resilience analysis for underground infrastructures, i.e. a societal risk analysis of the failures of underground services for an urban area. The approach is based on the detailed study of (1) domino-effects for the components of a single infrastructure and for a given set of infrastructures interoperated and/or belonging to the same area; (2) risk and vulnerability analysis of a given area; (3) identification of a set of intervention guidelines, in order to improve the overall system resilience. The use of an integrated (interoperability and area) approach, breaking down the analysis area extent into sub-areas and assessing the dependencies among sub-areas both in terms of interoperability and damage propagation of critical infrastructures, demonstrates a useful advantage in terms of resilience analysis, more consistent with the “zoned” nature of failures of the underground infrastructures. An applied case, describing the interoperability and damage propagation analysis with the evaluation of time-dependency for the infrastructures and targets and of different kinds of interventions of the underground infrastructures of a town, is presented for this purpose.

A probabilistic cognitive simulator for HRA studies (PROCOS)

Abstract The paper deals with the development of a simulator for approaching human errors in complex operational frameworks (e.g., plant commissioning). The aim is to integrate the quantification capabilities of the so-called ‘first-generation’ human reliability assessment (HRA) methods with a cognitive evaluation of the operator. The simulator allows analysing both error prevention and error recovery. It integrates cognitive human error analysis with standard hazard analysis methods (Hazop and event tree) by means of a ‘semi static approach’. The comparison between the results obtained through the proposed approach and those of a traditional HRA method such as human error assessment and reduction technique, shows the capability of the simulator to provide coherent and accurate analysis.

RISK AND CAUSES-OF-RISK ASSESSMENT FOR AN EFFECTIVE INDUSTRIAL SAFETY MANAGEMENT

It is widely accepted that progressive improvement of industrial safety is heavily dependent on the introduction of a systematic vision of man{machine{workplace interactions. In this respect, the risk assessment is one of the most critical tasks in the management of industrial safety. The paper presents a risk assessment approach, which uses analytic hierarchy process (AHP) to directly and holistically estimate risk, showing greater flexibility in comparison to traditional methods. In the rst phase (risk assessment), given a work task, the methodology allows to support risk characterization and prioritization of hazards within a hierarchical framework. In the second phase (causes assessment), the proposed methodology supports the influence analysis of the main causes of risk | machine, operator, procedures and environment | providing management with a more rational framework to make decisions and allocate resources devoted to safety improvement actions. The methodology is illustrated with reference to a case study concerning machining operations.

Towards enhanced collaboration and information sharing for critical infrastructure resilience: current barriers and emerging capabilities

This work presents a review of general issues and barriers to information sharing and collaboration during a critical infrastructure crisis response. An overview of the emerging concepts and capabilities that are promising for making an improvement in the field is also presented and discussed.

An algorithm for the implementation of safety improvement programs

In production system workplace environments, the achievement of safety objectives depends essentially on the risk assessment process and on the adequacy of measures to eliminate or reduce risk. The main goal of the planning phase is to define in advance the effective management of resources (financial, human and technical) involved in the completion of the overall safety improvement program. Indeed, whereas the results of the risk assessment process depend only on the correct evaluation of the work system with respect to human safety, the planning phase of safety improvement program is subject to economic, technical and organisational constraints and has to be integrated with other company objectives. Within this context, the plan definition should include additional objectives other than risk reduction, such as the clustering of measures with homogenous or compatible characteristics and the minimisation of production system disturbance (inefficiency) over the program time span. However, no safety improvement program can really be implemented if operational constraints (i.e. finite availability of resources, incompatibility in the execution of measures and limited acceptance of inefficiency) are overlooked. The present paper proposes a quantitative view of these objectives and constraints in order to develop an algorithm for the scheduling of measures within a safety improvement program. By means of the evaluation of a priority index, this algorithm provides a plan with the higher rate of risk reduction possible that maximises the objectives in function of their relative importance, obeying the imposed constraints. The definition of the safety improvement program for a textile factory shows how the algorithm can produce a plan with higher rate of risk reduction in comparison with plans based only on risk priority.

COMPETITIVENESS OF SMALL-MEDIUM, NEW GENERATION REACTORS: A COMPARATIVE STUDY ON CAPITAL AND O&M COSTS

Smaller size reactors are going to be an important component of the worldwide nuclear renaissance. An inappropriate application of the economy of scale would label the small-medium size reactors as not economically competitive with larger plants because of capital costs (