Occupational Health and Safety Risk Assessment for Demolition Processes in Construction

Introduction

Every branch of industry generates specific risks of occupational safety that are arising from the work environment, the workplace and the necessary resources for the work operation. Increasing complexity of work processes requires more time and resources for organization of the same in a safe way. The building process has all the characteristics of a very complex process: each object that is being built is a specific, process requires a large number of participants and stakeholders, the problem of design and construction is present, a large number of different types of materials, tools and machinery is needed, the building process is exposed to weather conditions, the movement of workers, materials and machinery is present in one or more buildings, education of the workforce is low, and so on. Despite being one of the most significant branches, construction industry features the highest injury rate [1, 2, 3, 4, 5, 6]. The occupational health and safety system is based on the application of the prevention principles for injuries at work, illness or damage to the health of an employee which must be carried out before starting the works. This is a prerequisite for the opening of each construction site in the Republic of Serbia. Risk assessment of injuries at worker employee illness is based on the determination of safety hazards on the workplace and work environment which can cause injury and probability of their appearance and it is thoroughly defined in the Occupational Health and Safety Law of Serbia [7] as well as in Rulebook for risk assessment [8]. Prior to the commencement of the work, it is necessary to assess the risk from the aspect of safety and health of employees, taking into account selection of work equipment, conditions of working environment, personal protective equipment, materials used in the working process, adaptability of work places and work environment to the employees. Risk assessment at the workplace and working environment is introduced with the aim of complete elimination of safety hazards, which should be sought in the conduct of the procedure. However, as it is usually not possible, the level of safety hazards should be reduced to the lowest possible extent. By introducing the principles of risk assessment and implementing the prescribed assessment procedures, we can effectively perceive the safety and working conditions in all workplaces. The manner of implementing the risk assessment process is defined by a standardized set of steps that are in line with the recommendations of the relevant laws, as well as the recommendations of good practice. Figure 1presents an algorithm with these steps.

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Methods for Risk Assessment

Risk assessment is a process based on precisely defined activities that need to be realized in order to define risk events that can lead to disturbances of the system being monitored [11]. As the construction industry is a non-stationary type of industry, in the sense that the process is being constantly modified and changed in order to build an object, the risk assessment process is more complex than other industrial branches. It is necessary to implement it for every construction site where the working conditions, workers, subcontractors, suppliers, applied materials, machinery and even contract documents are often changed [12]. In order to carry out a risk assessment, it is necessary to identify and analyse all possible sources of safety hazards, and then approach the evaluation of intensity - levels of risk ranking. Safety hazards are classified according to the current Rulebook of methods and risk assessment procedure for the workplace and working environment (Table 1).

Recognition Of Hazards On The Work Place

Grouping the hazards Groups of hazards Subgroup of hazards Šifra

Insufficient safety due to rotating or moving parts 1 Free movement of parts or materials that may cause injury to an Mechanical hazards that occur using equipment for Internal transport and movement of machinery or vehicles, as well as movement of certain equipment for work 3 Use of hazardous materials for operation, which may cause explosion or Inability or limitation of timely removal from the place of work, exposure to closing, mechanical shock, matching, etc. 5 work Auxiliaries for work (cables, chains) 6 Other factors that may appear as mechanical sources of danger 7 Dangerous surfaces (floors and all types of treads, surfaces with sharp Hazards that arise in relation to the characteristics of the workplace Working at altitude or depth 9 Working in a cramped, restricted or hazardous area (between two or more fixed parts, between moving parts or vehicles, indoor work that is

10 insufficiently lit or ventilated) Possibility of slipping or stumbling 11 Physical instability of the work place 12 Possible consequences or disruptions due to the obligatory use of resources or equipment for personal protection at work 13 Impacts due to illness of the work process using inappropriate or Other hazards that may arise in relation to the characteristics of the work place and the way of work (use of resources and equipment for personal Hazards arising from the use of electricity protective at work that burdens the employee, etc.) Hazard of direct contact with parts of electrical and voltage equipment 16 Hazard of indirect contact 17 Hazard of thermal effects developed by electrical equipment and installation 18 Hazard due to thunder stroke and the effects of atmospheric discharge 19 Hazard of harmful effects of electrostatic charge 20 Other hazards that may appear in connection with the use of electricity 21 Chemical damages, dust and fumes 22 Physical hazards (noise and vibrations) 23 Biological hazards (infections, exposure to microorganisms and allergens) 24 Harmful effects of microclimate (high or low temperature, humidity and Unsuitable - insufficient brightness 26 Harmful effects of radiation 27 Harmful climate effects (outdoor work) 28 Hazards arising from the use of hazardous materials (toxic substances) 29 Effort or physical strain (manual transmission of the load, pushing or Non-physiological position of the body (long-term sitting, standing, Efforts in carrying out certain tasks that cause psychological stress Conflict situations, insufficient motivation for work, management

raking prop was made to the top and bottom panels, 15cm thick. The main bridge construction was rigidly connected to reinforced concrete pillars and it was not possible to demolish the bridge continuously due to the danger that parts of the main bridge construction would enter unfavorable static influences into the pillars. For this reason, only the panel elements of the box-shaped girder (footpath’s consoles, upper and lower slabs) could be independently demolished without supporting. For the further demolition of the main bridge girder it was necessary to set supporting scaffold in order to prevent deformation and entering of negative impacts in pillars of the old bridge (Figures 2 & 3).

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Conclusion

Construction is one of the most diverse industry sectors in terms of the possibility of injuring and endangering the health of workers. The increasing number of incidents on the construction sites and levels of their severities require additional emphasis on the development of the workplace safety plan and program. Therefore, before opening the construction site in order to assess the risks and analyse safety, it is necessary to determine high level safety hazards that may occur. There are many methods for risk assessment, none of them is universal. In this paper, three methods were applied and analysed (matrix 3x3, AUVA and FMECA)in order to identify high level hazards for of demolition works at three construction sites. For each of them three characteristic work places (construction site manager, machine operator and labourer) were analysed. Different results were obtained when performing the risk assessment and it has been concluded that all three listed sites had increased risks of safety hazards. According to the obtained data and the characteristics of the applied methods, it can be concluded that for the analysed facilities the highest sensitivity was shown by FMECA method. Using the FMECA method, a greater number of identified safety hazards with increased risk was obtained in relation to the other two methods. Due to professional illnesses that hazard can cause, it is best to use a method or combination of methods that will thoroughly analyse each identified hazard. The choice of demolition technology also influences the assessment of the risks as well as the health and safety conditions at the site. Since the analysed facilities were located in the populated parts of the cities or in the vicinity of used facilities, cutting or crushing technology is the most appropriate solution. When using this demolition technology there are increased risks for the following identified safety hazards: insufficient safety due to rotating or moving parts, free movement of parts or materials that may cause injury to an employee, internal transport and movement of machinery, the impossibility or limitation of timely removal from the place of work, exposure to closing, mechanical shock, chemical hazards, dust and fumes, physical hazards (noise and vibration). Accordingly, for this demolition technology, greater attention should be paid to the mentioned safety hazards involved in risk assessment. When assessing risks, the best it would be to form a team of competent individuals and use all the present databases. The health and safety professionals as well as construction managers should be very careful when using presented methods. Many poor decisions can be made if they rely only on the results obtained from the risk assessment.

Acknowledgment

The work reported in this paper is a part of the research within the research project TR 36043 "Development and application of a comprehensive approach to the design of new and safety assessment of existing structures for seismic risk reduction in Serbia", supported by the Ministry for Science and Technology, Republic of Serbia. This support is gratefully acknowledged.