8 QR of RTRI, Vol. 54, No. 1, Feb. 2013 Yoshinori YOSHIDA Researcher, Ichiro SUGIMOTO, Ph.D. Laboratory Head, Development of Composite Steel Girder and Concrete Slab Method for Renovation of Existing Steel Railway Bridges Akira TANIKAGA Researcher, Steel Hybrid Structures Laboratory, Structure Technology Division Over half the existing steel railway bridges in Japan have been in service for more