Abstract
The process of erection, dismantling and alteration of heights in tower cranes are major safety determinants on construction sites and can result to fatal accidents if the risks involved are not properly managed. Risk factors associated with this process have been identified by some researchers but, no effort was made to scientifically analyse these factors. Hence, the research aimed at assessing safety risk factors during installation and dismantling of tower cranes with a view to establishing the most significant risk factors. A well-structured questionnaire was used to collect data from safety managers, equipment managers and team leaders of installation and dismantling operation with respect to probability/likelihood of occurrence and degree of impact for safety risk factors.Data obtained wereanalysed using descriptive statistics (mean and percentages). From the results, relative significance index score (RSIS) was obtained and evaluated on a 5×5 matrix risk rating scale to determine the criticality of safety risk factors. Results showed that ―abrasion‖had the highest probability of occurrence with a mean value of 3.63 and as such, the most probable factor that occur on site. The study also found that ―fracture of a wire rope during dismantling‖ had the highest degree of impact with a mean value of 4.63 and can result to fatality on site. The latter also had the highest RSIS of 15.6 indicating a high risk factor. This research concludes that fracture of a wire rope during dismantling is a high risk factor and could result from poor maintenance culture that is generally lacking on construction sites.
CHAPTER ONE
INTRODUCTION
Background to the Study
Tower cranes are used on construction sites as lifting equipment for their combination of height and lifting capacity. Tower crane accidents, however, are likely to be fatal because of the weight of the objects and the heights to which they are lifted (Beavers, Moore, Rinehart and Schriver, 2006). U.S. Labour statistics recorded 632 crane-related construction worker deaths from 611 crane incidents and 17 multiple death incidents resulting in 38 deaths from 1992 to 2006 (Bureau of Labour Statistics, 2008).
A crane safety analysis and recommendation report carried out in Singapore by Annex (2009) indicates that in 2008, there were 162 crane-related accidents, injuries and dangerousoccurrences, a 27% increment from 128 cases in 2007. However, most of the cases involve less serious non-fatal injuries crane accidents can undoubtedly result to big and severe damage to physical properties and human lives.
Orji, Enebe and Onoh(2016) posit that construction processes in Nigeria are characterized by unsafe practices leading to accident that leaves severe consequences on both the project and the workers. Accidents in building construction sites, whether minor or fatal could result to injuries, loss of resources, partial or permanent disability and death in case of fatalities. In an analysis of types of accident that usually occur in construction sites, injury from the use of equipment ranked first among nine (9) other types of accident examined.
Idoro (2011) asserted that although there is no reliable construction accident/incident data in Nigerianevertheless, a study carried out on 40 contractors in 2006 showed that the rate of accidents and injuries in the Nigerian construction industry were high and the most.
