Box girder bridges were a popular choice during the road building expansion in the 1960s. A serious blow to this use was a sequence of five serious disasters, where new bridges failed or collapsed in 1969 (Danube bridge in Vienna), 1970 (West Gate bridge in Melbourne, Cleddau bridge in Wales), 1971 (Rhine bridge in Koblenz), and 1973 (Zeulenroda); see [8.14]. All accidents happened during construction that was made by incremental launching, where new segments are placed onto the completed portions of the bridge until the bridge superstructure is completed. It was found that failures were primarily due to plate buckling of the bottom flanges that were subjected to compression at the cantilever support (Figure 8.1). These bridges were designed by different codes, so that their revision was set as a priority of the time. Since then, a lot of effort was made to provide safe buckling rules that will be presented in this chapter.