AADT Estimation and Validation Tools for Local Off-System Public Roads

Per the Fixing America’s Surface Transportation (FAST) Act of 2015, states are to have estimated Annual Average Daily Traffic (AADT) values on every paved road in the state by September 30, 2026. This will allow the Idaho Transportation Department (ITD) and local agencies the ability to better model safety. ITD has been tasked with coming up with an accurate and reliable mechanism to estimate traffic on every road in the state. ITD’s existing traffic counting program covers all “federal aid” roads within Idaho but does not extend to local, rural, and other off-system routes. The need for expanded traffic counts (or volume estimates) is driven, in part, by the federal recommendations for roadway data collection described in the Model Inventory of Roadway Elements (MIRE). MIRE includes a set of roadway characteristics and traffic inventory elements that are considered critical to safety management. Currently, ITD maintains AADT estimates on approximately 12,000 centerline miles of roadway. This requirement extends that an additional 44,000 centerline miles on which ITD needs to establish an AADT estimate. In addition to federal recommendations, the expanded counts (or volume estimates) are requested for all public roads by ITD’s traffic safety group to use for crash analytics. The objective of this project will be to develop comprehensive implementation and validation processing tools for estimating AADT values on every local non-federal aid public (off-system) road in Idaho using a geospatial interpolation methodology, ArcGIS, and Python.