The parameters relevant for prediction of service lifetime with respect to chloride ingress are associated with large uncertainties. Full-scale measurements are in demand for conditions which are as homogeneous as possible. The present paper first summarizes statistical distributions which are obtained based on measurements from the Gimsøystraumen bridge in Norway. These probability distributions are subsequently employed as input to a prediction model for chloride concentration at the steel reinforcement for a single but arbitrary position along the reinforcement. In order to address chloride attack on the entire bridge, a system model with 90 components is next introduced. This model is employed in order to perform reliability updating based on observations at a number of sites along the bridge. An Enhanced Monte Carlo simulation method (EMC) is applied for this purpose. It is shown that application of this simulation method reduces computation times significantly as compared to crude Monte Carlo methods.