The Kintai Bridge in Japan was constructed in 1673. It consists of two spans of girder bridges on both ends and three spans of arches in the middle. Chinese immigrants brought the techniques for building arches to Japan in the seventeenth century. The local carpenters adopted the idea of the arch, but whereas the Chinese built them in stone, the Japanese chose to construct their bridge in timber. This material transformation was achieved through innovations in technology, such as surveying, accurate drawing, the processing of wood and the use of metal parts, among other things. The Bridge has been maintained ever since by a society of local carpenters through a tradition of regular rebuilding and ongoing repairs. The engineering know-how to maintain the bridge has been passed down among these local carpenters, involving detailed elevation drawings, special tools and oral tradition.