The concept of smeared cracking has been adopted for the safety evaluation of masonry arch bridges. In order to realistically simulate the specific load-carrying behavior of such structures nonlinear analyses are required. The formulation of appropriate failure criteria and the safety concept are discussed. Parametric studies show the influence of the assumed material parameters on the calculated safety level. Based on the numerical results and on the experience with the analysis of real masonry arch bridges, recommendations for sufficiently accurate and computationally efficient nonlinear finite element analyses of these structures are formulated.