Statewide Performance Function for Steel Bridge Protection Systems

A performance function is the relationship between the bridge paint condition rating and time. This function reflects the level of service of the bridge paint. The performance functions of steel bridge paint for state structures maintained by the Indiana Department of Transportation (INDOT) were developed using both regression analysis and Markov chains. The regression and Markov models were used to predict the condition rating of a bridge’s paint at a given age. The probabilistic model that was developed with Markov chains was used to reflect the stochastic nature of bridge paint conditions. These deterministic and stochastic methods have been applied to the existing and the new bridges’ paint systems in INDOT structures. The existing paint systems are lead-based and zinc-vinyl. On the other hand, the new paint system is three-coat. The results indicate that both models are very efficient in representing the deterioration model for bridge paint systems based on historical data.