For expressways, the soundness of bridge RC slabs has been evaluated with the free lime method for many years. In this study, the deterioration of RC slabs is predicted with the data accumulated through visual inspection. In detail, the mixed Markov deterioration hazard model is adopted, and deterioration prediction is conducted, while considering the heterogeneity in the deterioration process of each slab. In addition, the authors suggest a method for determining repair priority based on the relative evaluation of deterioration rate of RC slabs, and empirically discuss the appropriateness of the past repair, by comparing it with actual repair performance qualitatively. Recently, in addition to the free lime method, a method of evaluating the ratios of water leakage and peeled areas is being adopted tentatively. Based on the detailed information on each slab, the authors discuss how much the new method contributes to the improvement in prediction accuracy.

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 In this study, the authors propose a methodology for designing optimal scrapping and maintenance policies for infrastructures that are to be demolished due to the demand decline or the deterioration progression. Infrastructures are durable, and can be used continuously as long as there are no problems in safety or economic performance. This study is focused on the three scrapping and maintenance policies: (1) to demolish infrastructures immediately, (2) to maintain them under the minimum maintenance, and (3) to repair them constantly. Then, the authors propose optimal scrapping and maintenance models for designing asset management policies considering the demand and deterioration of infrastructures. In addition, the effectiveness of the proposed optimal scrapping and maintenance models is investigated through a case study.

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 In this study, the authors identified the vibration characteristics (natural frequency and vibration modes) of a 24-span steel railway bridge that has been used for 86 years, through a passing train test and an impulse hummer test. The 24 spans have the same structure and are used under the same loading condition and almost the same environmental condition. Identified vibration characteristics (up to 70Hz for 12 modes) were compared, and it was found that there are no significant differences in vibration characteristics among the 24 slabs and even after 86 years of operation, vibration characteristics can be kept homogeneous through appropriate maintenance. In addition, the relation between the identified vibration characteristics and the bridge/train specifications was analyzed, and it was clarified that at the measurement points nearer to rail joints, mode amplitude becomes larger and its influence varies with modes.

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 In this study, the authors attempted to extract the vibration characteristics of a railway bridge from the axle acceleration response of a running train, in order to provide fundamental information for movable monitoring. Firstly, a passing train test was conducted using actual trains and bridges, to extract predominant frequency, which can be observed only when a train passes a bridge, from the frequency characteristics of axle acceleration, and their repeatability and speed dependency were checked. Then, the extracted frequency and the natural frequency of the bridge were compared to identify the predominant mode and clarify the effects of train speed and direction, etc. on natural frequency. In addition, using the acceleration response measured at a bridge, the variation in the components of the predominant mode of the bridge was analyzed. As a result, it was found that the natural frequency of the bridge around 82Hz contributes to the development of the predominant frequency of the train axle.

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 The Japanese construction market has decreased since the late 1990s. In under-populated areas, diversification of construction companies into agriculture and forestry has begun to maintain local economy.
 1. The local construction companies that entered agriculture are investigated, and current situations, issues and possibilities are verified.
 2. The local construction companies aiming at the forestry entry are investigated, and current situations, issues and possibilities are verified.
 3. Problems of both forestry and agricultural entries are arranged, and the measures are examined.

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 The objective of this paper is to make a statistical analysis on bidding results in projects in 2006 to 2010 to which technical proposal type of comprehensive bidding evaluation method is applied by Ministry of Land, Infrastructure, Transport and Tourism so as to evaluate the current competitive situation. It was found by analytical results that intensive price competition lower than the critical investigation price has occurred especially in projects which are categorized in tunnel construction, shield tunnel construction and prestressed concrete construction. Furthermore, it was revealed that numbers of bidders were more and the difference between the highest score and the second highest one were smaller in above 3 categories of projects than those in the other categories of projects.

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 Non-structural components of berthing facility such as yard apron and ancillaries are important equipment for ensuring safe and smooth operation in the facility. They often suffer deterioration and deformation under severe environmental and usage conditions, however, quantitative evaluation method of decline in their functional performance has not been developed to date. The decline in functional performance of ancillaries would consequently become one of main causes of decrease in safety and serviceability of the facility. This paper reports the results of the factual investigation on the decline in functional performance of berthing facilities with focusing on deterioration and/or deformation observed in face-line of wharf, yard apron and ancillaries, such as bollard and fender. The problems for developing quantitative evaluation method of functional performance from the viewpoint of safe and smooth operation in the facility were made clear from the investigated results. Applying the sensory evaluation technique, the influence degree on functional performance and the relationship between deterioration grades of each member and functional performance were evaluated statistically. Finally, an evaluation method of functional performance was developed for achieving the strategic maintenance of berthing facility.

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