For the pretensioning method, the process of producing prestressed concrete girders is similar to that of reinforced concrete. However, unlike reinforced concrete, special steel strands are used and pretensioned prior to placing the concrete. Prestressed concrete bridge girders are typically designed to resist high tensile stresses in the bottom flange of the girders at midspan. This is achieved by placing the pretensioning steel strands in the lower portion of the girders (McDonald 2005).