Among all the reasons for the bridge breakdown, scouring is the biggest danger. To reach the appropriate level of security and reliability for a bridge, its breakdown risk needs to be calculated. In this research to expand the risk assessment application in the bridge safety/reliability, the bridge abutment scouring equations are assessed for their reliability based on the probability distribution of the effective parameters in those equations. These parameters include channel shape, abutment shape, sediment, and stream flow. To evaluate each equation’s breakdown probability, Monte Carlo analysis is used and reliability index of each equation is going to be compared. In the conclusion, among the equations, the equation with the least breakdown probability and higher index of reliability will be chosen as the appropriate equation. In addition the results show that the uncertainty of the parameters should be included in the bridge abutment scouring. Among those parameters, uncertainty in depth and flow speed has the most dominant effect in the bridge abut scouring. Keywords Uncertainty, Risk Analysis, Scouring, Bridge Abutment, Monte Carlo Simulation
