The open-cut work of Fukudai Tunnel is one of the few cases for its neighboring construction and large-scale excavation (width=about 45 meters, depth= about 10 to 20 meters), and the work was carried out up to approximately 5 to 8 meters vertically above the common utility duct of Fukuoka Outer Beltway and Fukuoka City Subway Line 3 Tunnel, which were both constructed by small diameter NATM method.
 Especially, ensuring safety for tunnel structure and railway track were the important issues, since the commencement day of services of Fukuoka City Subway had been scheduled during the construction work of Fukudai Tunnel. On the other hand, behavior of ground and mountain tunnel, in case of open-cut work being carried out right above the existing mountain tunnel, has been indefinite and prediction method of impact has not been established.
 The purpose of this paper, using the FEM analysis, is to predict the safety, in advance, to inspect the result of construction test, to clarify the behavior of existing mountain tunnel while open-cut work is being carried out right above itself and to propose the impact prediction method focusing on the deformation modulus and join conditions between the tunnel lining and the ground.

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 Recently, the widely adopted Comprehensive Evaluation Bidding System put Japan into a new era of public works bidding system. Design-build bidding system is an example of this new system. Expressway companies have initiated several pilot projects using this type of bidding. The New TOMEI Aokikawa Bridge of Central Nippon Expressway Company was one of the trial projects that implemented this design-build bidding. In this paper, the mechanism of adopted bidding process is discussed and verified to point out its advantages and disadvantages for the employer and contractor. The unique characteristics of design-build bidding process, the discussion between employer and contractor after successful bidding, and solution to problems in the actual project during detail designing stage are explained. Finally, recommendations for the further development of this system are proposed.

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 The author studied the possible causes of issues that civil engineering facing in recent years from a philosophical point of view with the consideration of the history of civil engineering, and proposed some solutions for its future development. The causes of criticism for Japanese public works result from under-taking constructions in relation to wills of officials in charge rather than obtaining desired consensus of public for such undertakings. As a result of rapid development of social infrastructures of Japan under the influence of European views and it utilized resources without any restriction after the Meiji era and did not pay much attention to the destruction of natural ecological system of the earth. Therefore, I demonstrate the need to establish the public philosophy and the restoration of the harmony between the nature and public projects from a Japanese perspective valuing the nature and to put a distance from the western approach in civil engineering.

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