ECONOMIC LIFE

This is the period over which the equipment can operate at an acceptable operating cost and productivity. The economic life is generally measured in terms of years, hours, or in the case of trucks and trailers in terms of kilometers. It depends upon a variety of factors, including physical deterioration, technological obsolescence or changing economic conditions. Physical deterioration can arise from factors such as corrosion, chemical decomposition, or by wear and tear due to abrasion, shock and impact. These may result from normal and proper usage, abusive and improper usage, age, inadequate or lack of maintenance, or severe environmental conditions. Changing economic conditions such as fuel prices, tax investment incentives, and the rate of interest can also affect the economic life of equipment. Since the lives are given in terms of operating hours, the life in years is obtained by working backwards by defining the number of working days per year and the estimated number of working hours per day. For equipment that works very few hours per day, the derived equipment lives may be very long and local conditions should be checked for the reasonableness of the estimate.