The Kentucky Transportation Cabinet (KYTC) has moved toward a data-driven decision-making process, the Strategic Highway Investment Formula for Tomorrow (SHIFT), to allocate funds for highway improvement projects. SHIFT requires that candidate projects be scored on five critical metrics: safety, asset management, congestion, economic growth, and benefit/cost analysis.

The measure of congestion used in SHIFT 2018 was a combination of volume-to-service flow ratio (VSF) and design hourly volume (DHV). VSF is a traditional performance measure developed based on limited data, primarily for sketch planning purposes. However, it does not accurately reflect the dynamics of traffic congestion of many facilities.

This report presents a framework for integrating third-party speed data (acquired from HERE Technologies) into traditional congestion performance measures for use in SHIFT 2020. The speed data came from aggregated GPS-based vehicle locations at various temporal and spatial resolutions collected from 2015 to 2017. Data assessments undertaken by the research team found these data offer adequate coverages for monitoring congestion performance on most highways in Kentucky, except for some rural low-volume roads.

An automated process was developed to conflate HERE’s proprietary network, to which the speed data are attached, and KYTC’s Highway Information System (HIS) network. Spatial integration lets the Cabinet link speed data to a state-maintained inventory database, enabling additional applications beyond those addressed in this study, such as the calibration and validation of travel demand models.

The research team evaluated several performance measures that could potentially be applied in Kentucky. Based on this assessment, Vehicle Hours of Delay (VHD) is recommended as the best measure for quantifying congestion on a highway section. Two other measures – Vehicle Hours of Delay Per Mile (VHDPM) and Average Hours of Delay (AHD) – may be considered alongside VHD when performing network screening to identify bottlenecks. The research team, based on feedback from Cabinet work groups, developed a procedure for estimating VHD on highway improvement projects. A white paper in Appendix A documents this procedure.

Report Date


Report Number


Digital Object Identifier



© 2018 University of Kentucky, Kentucky Transportation Center

Information may not be used, reproduced, or republished without KTC’s written consent.

The contents of this report reflect the views of the authors, who are responsible for the facts and accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the University of Kentucky, the Kentucky Transportation Center, the Kentucky Transportation Cabinet, the United States Department of Transportation, or the Federal Highway Administration. This report does not constitute a standard, specification, or regulation. The inclusion of manufacturer names or trade names is for identification purposes and should not be considered an endorsement.