Optimum rehabilitation schedule of steel highway bridges

Every bridge component has a different deterioration rate, rehabilitation cost and costeffective treatment time. The cost-effectiveness of the timings of bridge component rehabilitation is investigated both for individual components and for combinations of components, with the objective of finding optimum bridge life and the most cost-effective rehabilitation schedule. The optimization model makes use of: ( 1) deterioration curves to predict the condition of bridge components with respect to bridge age; (2) benefit/cost analysis to identify the most cost-effective rehabilitation schedule. The study was conducted using Illinois data for steel bridges covering the period 1976-1998. The results show that the most cost-effective timings of rehabilitating individual bridge components are signifcantly different if the rehabilitations of different components are combined and treated as parts of a system. The results of the analysis indicate that optimum bridge life is 74 years with a best time of combined rehabilitation of both the deck and superstructure in year 44. The study is an attempt to improve current methods of scheduling bridge maintenance, repair and rehabilitation.