One source of confusion for the communities is 44CFR 60, Subpart B (section ) titled Requirements for State Flood Plain Management Regulations, which applies to structures on State owned properties. Structure is defined in as a walled, roofed building. Hydraulic structures such as bridges, culverts, and storm drains are neither included nor considered because for the purpose of the NFIP they are not insurable structures. Subpart B does apply to TxDOT office buildings, maintenance or repair shops, and highway rest area facilities.