Activity based risk assessment and safety cost estimation for residential building construction projects

• We examine drawings, bill of quantities etc. of 25 concrete buildings in Istanbul.
• Ratio of safety cost to the total construction cost is 1.9% according to 2013 rates.
• Safety cost per man-hour is 0.85 USD and safety cost per unit area is 5.68 USD.
• We compare our results with a research that focused on 30 projects in Istanbul.
• As the construction area increases, the share of the safety cost decreases.

Fatal construction accidents are major problem in Turkish construction industry. Although new comprehensive legislation has been inured recently; level of consciousness in the industry is unsatisfactory and safety is perceived as an extra cost. Small or middle scaled residential projects have a big share in the industry and majority of the fatal accidents usually occur on such work sites. Focus of this study is small and middle-scaled residential construction sites. Drawings, technical specifications, bill of quantities of 25 concrete residential buildings with total areas that vary between 230 and 118,200 m2 in Istanbul were examined. Site visits and information gathering were performed from site engineers. This study aims to give an approach for safety cost estimation for the early stages of construction bidding phase using risk assessment activities and construction project scheduling by focusing on construction activities. Additionally, a cost analysis was performed and the results were compared and analyzed with a former project that focused on 30 concrete residential projects in Istanbul. Primavera P6 was utilized for scheduling, and risk assessment was conducted using the techniques applicable for construction projects (i.e., L matrix and Fine-Kinney). Finally, activity-based techniques were used for cost estimation. The results of this study reveal that the percentage of safety cost to the total construction cost is 1.92%. Also, to comply with the current legislation and minimize risks; 0.85 USD per man-hour should be spent according to 2013 rates and safety cost per unit area was found as approximately 5.68 USD.