Kentucky Transportation Cabinet (KYTC) officials use annual average daily traffic (AADT) to estimate intersection performance across the state maintained highway system. KYTC currently collects AADTs for state maintained roads but frequently lacks this information on local roads. A method is needed to estimate local road AADTs in a cost-effective and reasonable manner. Kentucky Transportation Center (KTC) researchers conducted a literature review on U.S. AADT models but found that none of them were suitable to Kentucky. Therefore, KTC developed an AADT model using non-linear regression to estimate AADTs on approaches to those intersections.
KTC developed a Poisson distributed, non-linear regression model to estimate AADT. This model divided the state into three regions encompassing all of the highway districts: West (Districts 1, 2, 3, and 4), North Central (Districts 5, 6, and 7), and East (Districts 8, 9, 10, 11, and 12). This partitioning accounted for geographic and socioeconomic variability across the state. Each regional model relied upon three independent variables: probe count, residential vehicle registration, and curve rating. HERE proprietary probe counts—indicative of vehicle movements—provide tracking visibility on a select portion of vehicles moving across Kentucky highways. Residential vehicle registrations can be used to estimate trip generation information. Finally, the curve rating partially indicates accessibility.
Model results were adjusted to KYTC daily vehicle miles traveled (DVMT) county control totals for local roads. Sensitivity analysis was conducted to examine the impact of model errors for use in intersection safety analysis. Results indicate that the estimates generated can be effectively used for safety assessment and countermeasure prioritization.
Available at: http://works.bepress.com/eric_green/75/