Question 5 (20 marks) Consider the case Study - ALARP and gross disproportion, given in Appendix Q5. a) Critically explain the ERIC risk reduction model use in analysing risk in the design of structures and identify the key issues in the case study that might encourage a Structural Engineer/Project Engineer in using the ERIC risk reduction model in risk management planning. (10 marks) Appendix Q5 Case Study: ALARP and gross disproportion Consider the risk associated with a loading bay beneath a building in a city centre. A credible hazard is the impact of a vehicle into exposed columns. The hazard cannot be eliminated except through omission of the loading bay or its relocation outside the footprint of the building. The building footprint must be maximised within the site for the project to be viable. Servicing of the building is necessary but offloading off the street would not be permitted due to associated traffic congestion. It is therefore determined that measures by which the hazard would be eliminated are in gross disproportion to the magnitude of the hazard. Consequently it is legitimate to progress to the 'R' of ERIC: reduction of the risk arising. It would not be disproportionate to undertake a vehicle dynamics assessment to determine the maximum impact velocity for different types of vehicle. Nor would it be disproportionate to put protective bumpers on the columns such that the reinforcement cover is not lost due to successive minor impacts, or to implement an inspection regime such that impacts are identified and repairs undertaken. It may even be appropriate to consider the effect of an ensuing vehicle fire on the structure, given the importance of the columns and the likelihood of the hazard. Even with these risk reduction measures, there remains a degree of risk, however small. If the risk of terrorism is significant, a blast resilience study can be undertaken which considers any strengthening to reduce the risk of collapse under blast load and then determines the critical charge weight for collapse. This can be used to inform the development of security procedures governing the operation of the loading bay such that the client can control the risk through enforcement of security measures regarding vehicle access. Proportionate steps can therefore be taken to reduce the level of risk and an acceptable solution developed, with the background philosophy and any procedural measures necessary to control the residual risk communicated to the client.