When you approach a comparison of two codes from to different countries you expect to find very big differences, more over when for starters the unit systems are different. The first thing you realize when you approach the codes, Spanish and American, is that the American code is unique for roadways. In this code you find from the loads to consider to the calculations of limit states for every material you can use. The Spanish legislation is quite different; it has a code for steel and one for concrete. This two are to be used in any structure you find. For example when designing a concrete bridge in America you only need AASHTO but in Spain you need EHE for the concrete considerations and IAP for the loads on a bridge. In Spain if we wanted to do a steel bridge we will use IAP for the loads again but EAE for the steel consideration. On top of this, in the USA the design parameters can change from state to state, but always comply with AASHTO. The second thing noticed is that the two codes consider ultimate and service states, their approaches may in some cases vary, but they are all based in the same theory. They have different division within the ultimate and the service states, but their goal is the same: combine loads in different manners so different types of failure can be checked. Finally one thing that differs a lot from one design method to another is the use of standards. The American code and the departments of transportation use a lot of standards, pre-­‐design elements. The Spanish code doesn’t consider these pre-­‐design elements; normally each element is design for each construction, talking about concrete.