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Annual average daily traffic (AADT), which represents traffic on a typical day of the year, is used by transportation agencies for reporting requirements, allocating resources, informing decision-making, and supporting various agency functions. NCHRP Research Report 1124: Guide on Methods for Assigning Counts to Adjustment Factor Groups, from TRB's National Cooperative Highway Research Program, provides information and guidance on the methods for assigning counts to adjustment factor groups used in estimating AADT. Supplemental to the report is NCHRP Web-Only Document 406: Methods for Assigning Short-Duration Traffic Volume Counts to Adjustment Factor Groups to Estimate AADT.