strategic planning for the national bridge stock of iran

the national bridge stock of iran consists of about 330,000 bridges, of which around 50% are older than 30 years. since 2010, iran road maintenance & transportation organization has started implementing a comprehensive bridge management system in order to manage this aged stock efficiently. to predict future conditions of bridge stock, a heuristic numerical method is presented. this methodology is based on markovian process to model deterioration of bridge decks and a multi-objective optimization problem to find the best solutions. the optimization problem involves three decision variables regarding management strategies, and has three objectives regarding cost minimization. constraints of the problem are the percentage of deficient bridges, the percentage of bridges under mr&rs; (maintenance, repair and rehabilitation) and the average value of condition scores. the results show that to avoid future challenges, the annual budget for bridge maintenance should be increased, the current maintenance strategy should be improved as soon as possible, and national manuals and instructions for inspection, condition rating and maintenance should be developed.