A Delayed Gamma Process for Bridge Lifetime Assessment and Maintenance

The gamma process is a stochastic process with independent non-negative increments having gamma distributions. It is an infinite collection of probability distributions, correlated in a manner suitable for modeling gradual wear and degradation over time. Degradation generally consist of cumulative amounts of deterioration and the advantage of the gamma process is recognized by Jan M. van Noortwijk in the 1990's and applied in many structural studies. We introduce a novel stochastic process we call a delayed gamma process, designed for the estimation of infrastructure lifetime. An overview of the development of the model is given and the methods for estimation are reviewed.