Provision of side pathway & changing of corroded/loose Rivets in steel Girder Bridges of Bridge No. 13A, 16, 17, 30, 43, 9, 16A, of section SPJ-DBG-JYG and Br. No.4, 18, 80, 88,90, of section DBG-SMI-BGU section under SSE(Bridge)/SPJ of Samastipur