Building new infrastructure is a crucial part for developing society. Bridges are one part of the infrastructure that has large impact on both cost and climate. Such impact depends on the bridge design, which should be carefully chosen early in the project with several possible alternatives. In Sweden, it has become quite common to evaluate the Life Cycle Cost (LCC) and Life Cycle Assessment (LCA) for different bridge alternatives. This study investigates how three different steel materials in a steel-concrete composite bridge have different impact in a Cost-Benefit Analysis (CBA). In a CBA, all consequences for society are addressed and not only project specific aspects, in comparison to a LCC and LCA. The results show that the alternative with the lowest investment cost during construction is not the best alternative from a CBA point of view. This tells us that society and future generations will need to pay the extra cost if that alternative is chosen.