OSV (On-Site Visualization) is a monitoring system in which measured information is shared visually on a real time basis at site. It was introduced by Akutagawa in 2006 and it has been applied at various construction sites in Japan and overseas projects.

Through OSV application on various overseas projects, it has been recognized that a major problem with OSV system is the high cost of electrically driven OSV devices needed to cover many locations for a more effective OSV operation.

Based on the above observation, low cost OSV were developed and trial installation was conducted at the slope of National Highway in Vietnam.

Hanoi Metro Line 2 has been implemented since Mar 2011 under Japanese ODA and the construction works start in 2015. Because the underground station has deep open excavation works located at downtown in Hanoi, the careful construction operation with instrumentation and monitoring are required. In this paper, the plan of various type of OSV installation on Hanoi Metro Line 2 is proposed and the effectiveness of OSV monitoring is examined.

1. Introduction

Recently the installation of safety monitoring systems at construction sites has become mandatory and everyone recognizes the importance and requirement of safety. However the ratio of injuries and fatalities have not been reduced so much in Japan1 as well as other countries2.

A new approach for the safety monitoring of infrastructure and visually sharing the measured information on a real time basis was proposed by Akutagawa in 2006 and has been implemented in more than 50 construction sites including overseas projects in New Delhi and Bangalore3) - 6) to improve safety management practices. This new approach is derived by utilizing an On-Site Visualization system, whereby light emitting sensors are used as the key technology for monitoring and giving simultaneous visual presentation of the measured information of structure and ground movement information on site. Fig. 1 shows typical light emitting sensors developed for the implementation of the OSV by which the various phenomena and movements can be monitored and visualized on site in real time. The monitoring items can be listed as follows at normal construction site.

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