Mehrdad Hemasian - M.Sc student in construction Engineering and management,Eyvanekey university,Tehran,Iran
Shahin Dabirian - ph.D in construction Engineering and management,Lecturer at Art University of Isfahan,Architecture and Urban Design school,Isfahan,Iran

machinery has the main role in the development of the construction activities, enhancing the productivity of the machinery plays a crucial role in the reduction of destructions, their downtime and the delays of project delivery and its final effects. The objective of the present research is to develop machinery productivity and identify the most effective factor of machinery`s productivity in urban project through data collection of the by interviewing the experts, great constructors, managers, and machinery supervisors. Then, the data analysis has been done by dynamic modeling system by which the effective factors of the decrease and increase of the machinery`s productivity was identified to enhance the machinery`s productivity by taking suitable approaches and correct decisions.After identifying and classifying the effective factors of machinery productivity, and then analyzing the data and dynamic modeling system and also by taking the important role of the human being in productivity into consideration, it is concluded that management and taking the manager`s policies are the main reasons of dynamicity of the machinery productivity. Then, from among the two most effective management subcategories (for experts and in articles), the policy of renting and purchasing machinery and its maintenance were selected. Therefore, results have shown that in comparison with the other factors, the maintenance policy had the most effective correlation; then it is tried to develop this model based on simulation model (cause and effect relationship).

Construction equipment,Downtime , maintenance, Management