Bridge falsework productivity: measurement and influences

One principal element of the construction cost of a cast-in-place prestressed box girder concrete bridge is the erection of falsework. This paper presents the results of the analysis of labor-hours and quantity of work in erecting the falsework for 20 such bridges. Analysis of the bridge data has shown that the best productivity for falsework erection occurs when constructing a low structure on relatively flat ground. Location and design factors such as steep slopes, traffic openings, and tall structures, as well as such construction techniques as the use of cranes or lifts and the type of bent material selected, can reduce falsework erection productivity (measured through installation data for setting of pads, constructing bents, setting stringers, and rolling out the soffit) by over 50%. A belief network diagram was constructed to show graphically the falsework erection productivity influences identified through a study of the 20 bridges. With the collection of additional data, the belief network can be used to calculate a total falsework erection productivity value based on dozens of combinations of influencing factors.