Accident Rate on Building Site as a Quality Data in Simulation Model of Production Oleg Kapliński Poznań University of Technology, Poznań, Poland

Part I. Accident rate on building site & building firms in Poland. Part II. Accident rate in reliability model of production: The simulation model The empirical investigations An example of simulation investigations Remarks

Phenomena & conclusions (1): Regrettably, such accidents and health hazard are being more and more of a problem in Poland. The incidence of accidents at work in 1998 was 16.2% higher compared with The incidence of occupational diseases increased by 28.5 % in the same period of time.

There has been a significant growth in the number of private firms in the building industry, although its production potential in Poland is still extremely dispersed. It is in the small and medium building firms that the hazard of accidents at work is the highest. The emerging building firms, frequently family businesses with little expendable capital, are unwilling to invest in the machines and equipment that provide safe work conditions and personal protection measures to the personnel. Phenomena & conclusions (2):

The potential of the building production has been dispersed, affecting both employment and equipment. Orientation to maximized profit, which is mainly the case with small building firms, leads to limited expenditure, especially on protection of work stands, proper organization of building sites, adequate hygiene and sanitary facilities. It is a typical practice in tenders for building work to offer reduced costs, usually by cutting down on work protection spending. Phenomena & conclusions (3):

A number of such cases of faultiness originate from general fluctuations observed in the business. Detected and eliminated from one site, a hazard will be spotted in another work stand or building site, where the building work may even be carried by the same persons. Accident rate is an unstable phenomenon observed in our building business. Phenomena & conclusions (4): How to include phenomena such as the above in models of production processes?

Part II: Accident rate in reliability model of production Structure of disturbances in reliability model of production

Mentioned above accident and health hazard data are part quality and part quantity. It is possible to include data on accidents in other quality data and then, after combining them with quantity data, to bring them to a series with a simulation model of investigation into production reliability.

Two-state model with a series structure probability function, histogram, deterministic value Prerequisite (vii)

Prerequisites of the model: (ii) The distribution of the proper functioning in the system is a better measure of reliability, useful in the evaluation of production systems. (iii) The notion of systems reliability must be expanded: apart from inefficiency resulting from the breakdown of machines and equipment, there is also inefficiency caused by improper functional structure, organizational factors, absenteeism, accidents, decreased workforce efficiency, shortages in material supplies etc.

Fundamental elements of a series model Prerequisite (iv): (iv) Homomorphic transformation (vi) Decomposition & synthesis procedure (viii) subsystems

Examples of distributions (input of one phase in simulation model) a) Histograms of ability and disability of workpeople: Production of small size celluar concrete elements b) Ability and disability of overhead traveling crane

c) Work time and down time: cassette moulds in prefabrication plant d) Concrete heating and lack of stream: water vapour in Flow Production Line

Example of the analysis

period without changes after modernization Results of simulation of segments of proper work of the subsystem

period without changes after modernization Results of simulation of segments of breakdowns of the subsystem

Changes in the turn-table (element No. 6) and organization of the finishing line dept. (elem. No. 4) The reliability model was altered. Two phases (elements) were replaced. Elimination of downtime due to failure of equipment and injury to employees Availability factor increased to Availability factor 0.887

Results of simulation of segments of proper work (a) and breakdowns (b) of the subsystem under investigation

Final remarks (1) The problem of accident rate is to a large extent of a quality nature, therefore, it is difficult to identify and interpret them as quantity data in simulation models. Presented method is an example of inclusion of data on accidents at work in production modelling. In future, data on accident rate will be considered as quantity data as soon as data bases with records of equipment failure, downtime, accidents – e.g. in the form of histograms or coefficients have been created. Such comprehensive data bases, especially those on building firms, are still lacking.

We must act wisely and carefully while modelling of accidents and mechanical disturbances. Therefore, by means of mathematics, digital simulation and histograms we should not sanction uneconomical management and bad organization in plant, on building site or in building firm. Final remarks (2)