Although the ITA has had a Working Group on ‘Health and Safety in Works’ for many years, the number of published papers on the subject has, in the past, been relatively low. However, in the last five to ten years, how things have changed. At this year’s ITA annual gathering in Amsterdam the subject of safety and/or risk management was one of the Keynote Lectures and formed a whole section of the Proceedings. The need to identify, understand and manage risk in tunnel planning, design and construction was not far from everyone’s lips, and covered:
Safety in use
Most papers dealt with safety in use, which has gained importance as a result of recent fires in both road and rail, tunnels and following the work of the European Union(1) in the development of safety standards for road tunnels. Both and others(2) describe the substantial level of research that has been started by the European Commission to the value of US$15M. In recent years road tunnel traffic has grown significantly. Consequently the ‘safety level’ has decreased where measures cannot cope with the changed conditions and traffic composition. The EU research and development project, which started in September 2002, has brought together some 41 organisations to: develop and promote procedures for rational safety level evaluation and knowledge transfer in road tunnel fires; develop innovative means of tunnel monitoring and fire detection; and study human response and the effective means of protecting linings against structural fire damage. The objective is to restore public faith in tunnels as safe and reliable parts of transportation systems, and the levelling out of trade barriers arising from supposedly unsafe tunnels. Hoj and others(3) make the point that decisions should be made taking into account all available information with the goal of reaching the optimal solution seen in a life-cycle perspective. This involves: the identification of decision alternatives (and the possible outcomes); modelling uncertainty of information; and evaluation of the environmental impact and questions of durability, maintenance and ling repair. A second paper by Both and others(4) provides a particularly concise overview of tunnel lining spalling during a fire, and describes measures designed either to limit the damage caused by spalling or to prevent the spalling process itself. In terms of the safety of the public there are two case-studies of particular value – the first by Nelisse(5) concerning the determination of the safety system in the Westerschelde tunnel in Holland, and a paper by Baumelou(6) concerning the unique twin deck tunnel at the A86 in Paris for light vehicles. Nelisse writes that research has focussed on the decision making process during the design phase and had concentrated on aspects of the life safety of road users during calamities. In particular these included: the distance between cross passages; escape door width and the policy of opening these doors; and traffic management during a calamity.
Their evaluation framework consisted of five criteria: the completeness of the safety measures; the recognition of negative interactions between safety measures; the commitment of parties (owner, administrator, municipality, users, public auxiliary services); the use of knowledge; and the cost-effectiveness of the safety measures.
Safety of workers
In the Keynote Lecture on this subject, Ash and Betts(7) presented an “Australian perspective” on both safety and health in tunnel construction. After recalling historical safety comparisons, he went on to outline the thinking behind the measurement of worker safety at the Northside Storage Tunnel in Sydney. Whereas many international projects in the past had set performance objectives for safety based upon the ‘accident record’, in this case the authorities saw the use of such negative data as restrictive, being a measure of failure, and one that did not prevent injury but merely reported it. It was therefore decided to have a focus on measuring safety performance based on the application of a Safety Management System which had a built-in incentive scheme. The marking system involved 12 Elements, each of which was broken down into a number of criteria aimed at measuring improving levels of safety performance. In parallel to this, a well-respected behavioural scientist was commissioned to undertake a review of the ‘safety culture’ within the project workforce. He collected a total of 4,000 responses from 262 personnel from five work sites, and among his findings and recommendations he listed the key features as being: organisational factors influencing safety culture, behaviour attitudes and, in turn site safety performance; human factors impacting on site safety culture, behaviour, attitudes and, in turn, safety performance; and learning factors, safety education and training issues impacting on safety culture, behaviour attitudes and, in turn, safety performance.
Other matters influencing safety issues included: establishing competence levels within the workforce; correct recruitment practices; on-site training; the development of appropriate safe systems of work; and the effectiveness of accident and incident investigation.
In another paper, Anderson(8) makes a plea for the use of contracts between the parties to international tunnelling projects to reinforce the priority that should be given to health, safety and risk management issues. The effective management of health and safety issues can lead to a range of desirable project outcomes and not just the avoidance of personal injury or ill health.
In a paper containing rare detail, Grasso and others(9) describe the collapse of a surface building above a soft-ground tunnel during the construction of a metro system. After the event the authors describe the extensive supplementary investigations that were undertaken following the setting up of a special Task Force involving both local and international experts. While the detailed reasons for the collapse were to do with the specific ground conditions at the collapse site, the method of approach and recommendations are relevant to many soft ground TBM applications.
Papers about incidents that should not have happened are to be welcomed as they provide learning opportunities to the international tunnelling community.
Design risk management and safety
Reilly(10) relates risk mitigation to management and probable project cost, and in particular the business of reliably estimating the probable cost range of complex projects considering risk and variability implicit in future events. The author refers to recent research findings from a study of 258 infrastructure projects spanning 70 years saying that we, as an industry, have not corrected the chronic underestimation of the real cost of infrastructure projects at the time of decision making. Frequently ‘unforeseen events’ or ‘unforeseen ground conditions’ are blamed for cost growth and over-runs, but the obvious question is “why were these events not foreseen?”. The author advises a structured approach of risk identification, risk analysis and risk mitigation measures leading to a clear evaluation of a base cost assessment and validation, together with a further detailed examination of risks, and thus the development of projected costs and schedules related to or caused by potential risk events. Kolic(11) describes the risk identification and analysis carried out for a tunnel project in Croatia. The author states that the risk analysis starts “with three basic items: the project description; development of hazard scenario lists; and the definition of the risk acceptance level”. The author’s risk analysis is based upon the principles of: being transparent – the risk should be fully understood; seeking experience – the risk is measured and managed by people and not by mathematical models (even although some of them may be useful); and communication – the risk needs to be discussed openly “as the society where people speak about their risks will be more successful than one that discourages an open risk dialog.”
Figure 1 is reproduced from the paper by Kolic and it will be noted that the objective of this part of the exercise is for the “client and design group” to produce a pre-construction phase costed residual risk register, but only after an exploration of all potential problems and their causes and a rigorous qualitative and quantitative analysis. Sneldersë, in his more strategic paper, draws attention to the fact that underground spaces that we create nowadays rarely have one single use, and that safety issues are mainly led by experts whose discussions are largely led by rules and regulations. The author argues that multi-functional use of underground space calls for a totally different approach, bringing on board urban planners, architects and the future users of the underground space. Safety, he argues, should implicitly be part of the design process and “be given a chance to be addressed as an integrated part of the total design requirements such as: urban pattern and layout; architecture; social safety; orientation; special relationship and making the underground world a logical part of the world above”.
Conclusion
This conference has demonstrated that the need to identify, understand, eliminate (if possible) and control risk, is firmly part and parcel of the work of all parties to any tunnel project. The processes to achieve this may differ, but the objective is the same: less accidents and ill-health for people; less impact of the construction process on the environment; and more certainty about cost, time and project success. Getting it right means more money around to build more tunnels.
Related Files
Fig 1 – Residual risk realisation flow chart by D Kolic(11)
