The conservation and safety assessment of old masonry arch bridges represent nowadays a research field of considerable interest. Most of them are testimonies of the past with a significant historical and cultural value, and represent nowadays, a large part of the transport infrastructures serving strategic link for roads and railways networks. In many cases, their masonry primary elements are already deteriorated due to weather conditions and to the effects of cyclic traffic loads that are increased in both the frequency and the intensity with respect to the past.
Even if the ultimate load is not reached, the cumulated damage along with the localised deterioration can reach levels not acceptable, leading to the out of service of the entire structure.
In this paper, different models are applied in according to the stress-life curve method for estimating the fatigue strength and residual service life of a case study, an Italian ancient multi-span masonry arch bridge still in service
