This study is intended to look into the effect of construction safety supervision system on risk control and reduction. To achieve this, a survey was carried out to 114 companies in construction, ordering, contract and management. The overall findings were as follows. The effect of construction safety supervision system on risk control and reduction showed that factors of supervision system, supervision cost and supervision method had a positive effect on risk control and reduction. And their perception of the introduction of safety supervision system in construction sites according to process showed that there was a difference between them according to the field of ordering, contract and supervision. There was the biggest difference between owner and contractor in double supervision system, but no difference between them in the perception of risk reduction. These results show that all ordering, contract and supervision are positively needed for the introduction of construction safety supervision. This means that there is a difference between owner and contractor in the perception of process according to system operation. All companies agree to system improvement by the settlement of safety supervision system for the prevention of safety accidents and safe construction, but the systematic complement of safety supervision is the burden of contractor. And there is a big difference between owner and contractor in the perception of responsibility and concern for cost burden.

As there are more accidents which are more serious in construction site than other industries, it needs the safety management system to be SLIM on the same time, There are still lots of difficulties to prevent those accidents exactly, so it also needs a safety supervision team to prevent the accident, unsafe operation and condition before happening, which is also called as a Man-to-Man safety management method. The range of the job site in one personnel's management is very big and large, so it needs the personnel to keep watch the safety operation and prevent any unsafe/fire accidents. Also the personnel also should find out the unsafe points in the job site, and carefully supervise the dead angle site, then support the totally safety management POINT and realize the ZERO accident.

This paper investigates the potential impact of external factors on bid/no-bid decision for supervision consultant service on construction project in Hanoi, the capital of Vietnam. The data used in this study are secondary data taken from annual reports and sourced from the Department of Public Procurement, Ministry of Planning and Investment in Hanoi. Besides, to identify the impact of external factors on bid/no-bid decision for supervision consultant service on construction project in Hanoi, the study collected data from 272 qualified questionnaires from bidders doing business in Hanoi. Cronbach’s Alpha, EFA and regression model are used to explore the impact of each independent variable on bid/no-bid decision for supervision consultant service on construction project. The results show that three external determinants, including Project characteristic (PC), Legal codes (LC) and Competition (C) are affecting bid/no-bid decision for supervision consultant service on construction project in Hanoi. Among them, Project characteristic (PC) and Legal codes (LC) have positive relationships with bid/no-bid decision for supervision consultant service on construction project, whereas Competition (C) negatively affects bid/no-bid decision for supervision consultant service on construction project. It means the more contractors actually participate in a bid, the less bid/ no-bid decisions are made.