Steel railway bridges were constructed early, and the number of the bridges which there is more than 60 years after construction exceeds half of existing bridges today, and the number of the bridges needing repair, reinforcement and replacement tends to increase. Because the replacement of existing bridges has a long construction period and enormous expenses for the installing and removing the temporary line, girder and abutments, it is urgent to establish both life extension and seismic reinforcement method without the replacement for the existing bridges.
 Based on such a background, authors suggested the rational reinforcement method by the structure integration of steel girder-abutment type bridges. This paper describes the details of the integrated method of steel girder, abutments and backfills. It is explained the reinforcing experiment to the full-scale steel girder-abutment type bridge. In addition, the paper shows a series of experiments to investigate the effect of train vibrations to the freshly mixed concrete after casting, which decide the concrete casting condition for the integration between the steel girder and abutments. Finally it is described the effectiveness of the proposal method on economy and construction period comparing with the conventional replacement methods of existing bridges.

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 The pavement repair policy is planned and implemented based on the knowledge of pavement engineering, and improved constantly by reflecting the experience and know-how that have been accumulated by field engineers for many years. Therefore, it is difficult to scientifically discuss the appropriateness of pavement repair policies. After the development of road surface measurement vehicles, etc., enormous data of road surface conditions of expressways has been accumulated. In this study, the authors estimate the deterioration curve and expected lifetime of road surface statistically by using enormous inspection data, and propose a methodology for evaluating pavement repair policies by comparing them with actual values. In addition, the authors discuss (1) the evaluation indices for managing the road surface for which drainage pavement is increasingly used, (2) road surface inspection interval, and (3) the appropriateness of repair cycle, by comparing estimated and actual lifetimes of road surface, targeting the roads managed by Kansai Branch of NEXCO West Japan.

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 In this paper, the authors argue an optimal inspection/replacement policy for a tunnel lighting system which consists of lamps, ballasts and luminaires on an expressway. Deterioration processes of lamps and ballasts can be estimated by Weibull deterioration hazard models, and deterioration process of luminaires can be estimated by a Markov deterioration hazard model. By utilizing the deterioration forecasting result, the inspection/replacement process of the tunnel lighting system can be expressed as a Markov process model. As policy variables, the authors establish a) a flow of non-stationary inspection/replacement intervals of lamps, b) a repair policy of luminaires, c) an interval of simultaneous replacement of ballasts, and d) an interval of simultaneous replacement of the tunnel lighting system. At that time, the number of candidates of the optimal inspection/replacement policy is enormous due to the non-stationarity of inspection intervals. Therefore, the authors develop the method employing genetic algorithm in order to determine the optimal inspection/replacement policy which satisfies given risk control levels and minimizes the life cycle cost. Finally the effectiveness of the proposed method can be discussed through the empirical study of an actual expressway tunnel lighting system.

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 Maintenance of existing bridges is increasingly gaining importance. One of the biggest problems faced in efficient and optimal maintenance is establishing bridge management systems in local governments. This report analyzes the factors that allowed local governments' bridge management systems and organizational frameworks to get involved in such serious circumstances and also specifies the issues to be tackled in maintaining existing bridges through advising the bridge management committees of local governments. In comparison, the efficient and optimal bridge management system established in Hyogo Prefecture is examined in an effort to understand the factors underlying its success. After our discussion of what we learned from our experience, this paper extracts lessons that may produce useful knowledge for both reestablishing bridge management systems in local governments and promoting the integrated maintenance policy of bridges.

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 The authors have been developing a Bridge Management System (J-BMS RC and PC versions) integrated with the Concrete Bridge Rating Expert System (BREX) that is able to use to evaluate the service-ability of existing concrete bridges. J-BMS RC version consists of three subsystems; J-BMS DB'09 for accumulating bridges check data, RC-BREX for evaluating performance of reinforced concrete bridges and MPOS for support of planning of bridge maintenance. In addition, RC-BREX has two kinds of version; the qualitative RC-BREX'99 and quantitative RC-BREX'2000. The aim of this study is to develop a merging function of each subsystem for practical application of J-BMS RC version, because the current JBMS RC version didn't integrate among functions due to independent development. Furthermore, from the results of applying the system to two aged bridges being demolished in Yamaguchi area, it will be able to help to establish the rational maintenance strategies for existing concrete bridges.

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