The main goal of maintenance is prevention, timely detection and elimination of failures and damage. From the point of view of critical infrastructures (CIs), the main purpose of their maintenance is to increase the safety of CIs and / or to ensure life safety. CIs should be optimal in terms of their purpose, cost, as a source of income and profit at all stages of their life cycle, and also acceptable in terms of possible loss of human lives or injuries. The paper considers the assessment of necessary optimal investments in the maintenance (time interval between subsequent maintenance), to increase the safety of life, the so-called life saving costs. The problem of limiting the threat to human life is as follows: “how much money is society ready and able to spend to reduce the likelihood of premature death”. A quantitative criterion of risk acceptance is used, in which the marginal cost of life saving is compared with social willingness to pay. This value is determined using the life quality index of population
