The Federal Sufficiency Rating (FSR) is a federally mandated formula that is used in all states. It is a rating of 0 - 100, and indicates the bridge's sufficiency to remain in service. A zero rating indicates totally insufficient and 100 indicates entirely sufficient. The sufficiency rating is an overall score based on a number of items, such as structural adequacy and safety, age, serviceability and functional obsolescence, and suitability for continued public use. The sufficiency rating is one tool used by the South Dakota Department of Transportation to manage the State's bridge inventory, and cannot be used as the sole means of determining bridge structural status or overall safety. A low sufficiency rating may be attributable to non structural issues, such as narrow bridge roadway width, inadequate number of lanes, undesirable curves on the highway leading to the bridge, or inadequate vertical clearance between the bridge deck and the structure above.