抄録
Objective. In Japan, we built a large amount of infrastructures at the high economic growth period. Currently, they’re up for renewal time, therefore it’s anticipated that the costs of those maintenance management and renewal increase rapidly. There are threats of functional decline and serious accident in these dilapidated infrastructures. Moreover, when building construction work, it’s necessary to consider some social influence such as noise, vibration, and construction delay. National Institute for Land and Infrastructure Management advances development of “Strategic Stock Management Method”. Then, in gas utility, Ministry of Economy, Trade and Industry introduced risk management method in the guideline for aging pipes. They presented that setting priorities is indispensable for measures. So, the needs of efficient and appropriate infrastructure stock management rises. The purpose of this study is to propose the measuring method for maintenance management and renewal of infrastructures.
Results and Discussion. First, we account the initial construction cost, the maintenance management cost and the risk cost for combined sewerage pipes. At that time, the costs are separated into two pieces (internal costs and external costs), and accounted during the life cycle with area characteristic in mind. Internal costs are actually-occurred, and external costs are negative impacts of surroundings in construction. Then, these costs per year are added up, and to clarify minimized years. Therefore, we estimate appropriated renewal time considering breakage risk and social costs (internal costs plus external costs). As the result, the renewal time has been extended when consider social costs, compared to only internal costs. Thus, the appropriate renewal time is different considering not only internal costs but also social costs and risk.
Conclusions. Taking into account the social costs of construction in every region, that the results were compared to extended periods of evaluation and update only the internal cost. The major areas are shown quantitatively that the risk needs to be updated quickly than other areas. From the above, as well as internal cost of construction was found that the difference comes into play when considering the best term update the social costs and risks.
