Evaluation of Urban Bridge Useful Life from the Perspective of Traffic Overloading and Optimal Solution to Maintain Transportation Network Performance (Case Study: Felezzi Bridge in Isfahan)

Bridges are the most important and influential infrastructures in urban transportation networks. Isfahan transportation network has many bridges having important role in the performance of the network. Felezzi Bridge is one of the most important bridges at this network because of transferring traffic flow from north of the city to south and vice versa. Construction of this bridge was finished at 1959. At this study the impact area (10% traffic flow change range at the peak hour in 1393) was determined by omitting this bridge from the network in TransCAD software. Then scenarios and indicators were introduced to evaluate. Scenarios were assigned to the model. Then indicators was calculated for each scenario and converted to costs to compare with each other. Indicators were divided to 3 groups according to payers. These payer groups contain users, public and agency. User indicators are travel time, fuel and vehicle operation cost. Public indicators include crash costs, air pollution and noise pollution. Agency indicators are maintenance and construction costs, traffic service and facilities costs. The analysis period is until the end of bridge operation life (2029). Scenarios increasing supply reduce travel time but increase fuel and vehicle operation costs. Results show that summation of costs for users increase at these scenarios and demand management scenarios have lower costs for this group. On the other hand in public costs, crash and air pollution costs are reduced by operating supply enhancement scenarios and noise pollution are increased. It is clear that supply enhancement scenarios have more cost for agency than demand management scenarios.