The factor of safety is used in engineering and building to ensure that a certain object has enough strength in reserve to withstand breaking due to excess force or weight. The added cost can reach almost absurd amounts in aerospace; Surjan Singh estimates that it added 1.5 billion USD to the Space Shuttle’s cost. However, he does concede that the safety factor is a necessary price to pay to cover the gaps in human knowledge that could otherwise lead to catastrophic failure. Read full article here