In recent years, Observational Construction System (OCS) supported by monitoring and data processing system has increased importance for construction management. The purpose of OCS is to ensure safety and quality control and further to find out the optimum construction method by promptly feeding back the results of measurement to design. In spite of the importance of the method, there are few evaluation method for OCS because of the difficulty in analyzing the effect of the system.
The aim of this study is to take up the method of quantifying the effects of the use of the OCS from a view point of prompt alteration of construction method by monitoring and processing data. This paper discusses the characteristic of OCS and the method of quantifying such effects by cost-benefit analysis. Finally, this paper also shows the availability of the proposed method through the application for actual NATM works.