en Optimal analysis Optimal analysis پژوهشي Research Construction industry has the highest ratio of fatality of workers in comparison with other industries. Construction safety has been always a matter of focus to control safety risks. This article presents a new flexible method of safety risk assessment by adding Hybrid Value Number (HVN) to the assessment equation. As a result of using this method, the results of assessment process will be more consistent with the project’s conditions, as well as being more trustful. It could provide a better perspective of safety risks for project managers. The most significant outcomes of this research are as follows: 1) the most influential factors which affect safety risks in building construction projects are "the proficiency and the experience of workers", "the complexity of construction technology" and "time limitation", 2) the biggest risk priority numbers belong to "Struck by falling objects" and "Falling to lower levels" hazards, 3)a necessary safety program must contain Personal Protective Equipment (PPE), safety measures and safety training, 4)Project managers can decrease 75% of total safety risks by investing less than 1.5% of construction budget on safety programs. safety, risk assessment, hybrid value number, safety cost, safety program, building construction. 433 452 http://ijoce.iust.ac.ir/browse.php?a_code=A-10-66-194&slc_lang=en&sid=1 R. Ghousi 180031947532846001325 180031947532846001325 Yes M. Khanzadi 180031947532846001326 180031947532846001326 No K. Mohammadi Atashgah 180031947532846001327 180031947532846001327 No