The present research is based on the construction of a comprehensive and descriptive database of 58 concrete arch bridges (38 roadways and 20 railways) built in Spain during the last century. The collected information includes geometrical and mechanical data that are used to find out the main relations among different dimensions and parameters of the structures, further assembled to derive specific trends. These information have been combined with data collected by other relevant authors involved in the same issue as Salonga, Gauvreau and Manterola. In this way, a wider dataset has been obtained for bridges with similar features, allowing to have more reliable results.