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Section 3. RATING SYSTEMS 4-3.1 Numerical Evaluation. Numerical rating systems are useful methods for summarlzlng the condition of bridge and culvert components. When the conditions associated with a specific numerical value are well-defined and the rating system is clearly understood by both raters and reviewers, valuable information can be quickly extracted from the inspection reports. To achieve accurate and consistent results, clear definitions are needed on how the ratings are to be applied. For example, is an item rating based on average condition or on the worst condition found? Ideally the answer should depend upon the type and location of the defects found. Questions the inspector should ask when rating an item are: Is the item functioning as originally intended? Could it pose a threat to public safety and private property? Could it cause extensive damage if it is not repaired? Can the problem be repaired by maintenance action or will it require rehabilitation? 4-3.2 SI&A Ratings The results of all bridge and culvert inspections performed as part of the National Bridge Inspection Program are reported to the FHWA on Standard Inventory and Appraisal (SI&A) forms as previously illustrated in exhibit The information reported includes inventory data, condition ratings, and appraisal ratings. As noted earlier, FHWA publishes instructions and guidelines for recording each item on the standard SI&A form. a. Condition Ratings--Condition ratings are based on a comparison of the existing condition of the item being evaluated with the "as-built" condition. The following condition items are applicable to culverts: (1) Item 61--channe1 and channel protection (2) Item 62--cu1vert and retaining walls (3) Item 63--estimated remaining life (4) Item 64--operating rating (maximum permissible load) (5) Item 65--approach roadway alignment (6) Item 66--inventory rating A description of each of these six items is included in the COding Guide previously mentioned. With the exception of items 63, 64, and 66, SI&A condition items are rated using a numerical scale that ranges from "0" for closed and beyond repair to "9" for new condition. General descriptions of the conditions that apply to each number of the rating scale are provided in the COding Guide. b. Appraisal Ratings--Appraisa1 ratings are an evaluation of how the structure as a whole functions as an element of the highway network. Appraisal ratings also use a "0" to "9" numerical scale but are based on a comparison with current standards as opposed to "as-built" standards. General 60