The launching method means erecting bridge girders fabricated beside the point of erection by launching. With this approach, erection above an existing road, which ordinarily required road closure over three nights, can be completed in one night. We have accumulated expertise on safe erection within short periods of time, even for multi-width bridges, curved girders or other complex conditions. This method thus significantly helps to reduce traffic congestion caused by traffic regulation, and to prevent bad impact on distribution systems.