Traffic data, safety data, roadway conditions and the social and environmental context were assessed to understand the existing conditions within the US 27 corridor and adjacent communities.
US 27 through Highlands County runs as a four-lane divided and six-lane divided roadway with functional classifications of principal rural arterial and principal urban arterial within the study corridor. These existing characteristics are summarized in Figure 2. Note the functional classification switches between principal rural arterial and principal urban arterial as the corridor traverses the urbanized areas of Lake Placid, Sebring and Avon Park.
Existing traffic volumes were analyzed for the study corridor using available data from the 2023 Florida Traffic Online (FTO). As summarized in Figure 3, the Average Annual Daily Traffic (AADT) ranges from 9,400 to 44,000 vehicles per day (vpd) along the study corridor. The existing level of service (LOS) is LOS C, which is higher than the acceptable FDOT target of LOS D on the State Highway System in urbanized areas for peak travel hours. The highest AADTs are observed along US 27 around the Lakeview Drive/Sebring communities. Figure 3 also includes the truck percentages which range from 7% to 40%, with the highest truck percentages observed north of SR 70. Per Florida Traffic Online (2023), the northern and southern portions of the study corridor feature truck percentages between 20%-43%, with daily truck volumes 4,200 south of SR 66. Urbanized areas of the study corridor experience daily truck volumes between 2,800 and 3,400.
The FDOT District One Regional Planning Model (D1RPM v2.0) 2015 base year data and highway network in the subarea region was updated and validated to define existing transportation demand. The subarea analysis for model calibration includes a larger area of influence surrounding the US 27 study corridor including the existing parallel facilities of US 17, Sebring Parkway/Panther Parkway, SR 17 and CR 671, and connecting facilities of SR 70, SR 66, SR 64, US 98 and SR 60. The subarea region of the model produces a broader traffic analysis of existing facilities in Highlands County and evaluates the impacts of adjacent roadways in the future year analysis.
The purpose of the subarea validation for the base year was to reduce the discrepancy between the Base Year 2015 estimates on socioeconomic data and Base Year field network loading and the D1RPM 2015 base model for Highlands County. The employment data was adjusted, and the validation statistics provided Root Mean Square Error (RMSE) values within the allowable range, while simultaneously incorporating the difference in the socioeconomic data. The modification of employment data to match Bureau of Economic Analysis (BEA) totals resulted in the reduction of the volume to capacity (V/C) ratio from the default model. Since the deviation is seen more in the traffic analysis zones (TAZs) closer to Highlands/Polk County Line and Highlands/Glades County Line, a validation procedure involving adjacent counties is further needed to evaluate the regional traffic accessing US 27. The validated model along with National Cooperative Highway Research Program (NCHRP) smoothing method will be utilized for the 2045 forecasting, which will further reduce the discrepancy while minimizing the differences in the socioeconomic data. The subarea analysis is detailed in the Traffic Technical Memo in Appendix A.
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