below) and summarized to represent one average where a segment was sampled in multiple locations.
Figure E-2 : StreetLight analysis map of highway and surface streets sampled for 2021 AADT volumes
For the further calculations in this analysis, the Streetlight values were deflated to represent on-street conditions based on the volume calibration discussed previously. The Streetlight derived AADT values were multiplied by the ratio (82%) to derive a calibrated 2021 AADT value. Calculated growth rates for 2021-2023 were then applied to the calibrated 2021 AADT volumes to calculate 2023 AADT estimates. While a general growth rate of 1% has been used in the urban Atlanta area for other projects, an average 8% annual growth rate was calculated between 2021 and 2023 from the GDOT Traffic Database and 2023 Marr Traffic Counts on North Avenue. The high growth rate is due to volume decrease during peak COVID-19 years and subsequent recovery in 2022 and 2023. This rate should not be used for future volume forecasting and instead a minimum of 5 years of historic data should be used.
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