Mid-America Transportation Center
Mid-America Transportation Center: Final Reports and Technical Briefs
Date of this Version
2024
Document Type
Report
Citation
Mid-America Transportation Center, University of Nebraska-Lincoln, 2024
Report number WBS # 25-1121-0005-004-54
Abstract
Roadway performance measures are used for operating, planning, and design purposes to improve services for road users. Simple statistics of the performance metrics such as measures of central tendency (e.g., mean, median) are often used for making operational and planning decisions. Even though such statistics are useful, they are, more than often, not comprehensive enough for making insightful operational and planning decisions. Consequently, performance reliability measures, which attempt to capture the day-to-day variability in performance, have the potential to benefit the areas of operation, planning, and design. Traffic data from Intelligent Transportation System facilitates the measurement of the reliability of transportation systems. This project analyzes and verifies the accuracy of INRIX traffic data using a testbed located in Nebraska. In addition, different travel time reliability (TTR) metrics such as travel time index (TTI), planning time index (PTI), level of travel time reliability (LOTTR), buffer index (BI), and coefficient of variation (COV) were measured for Region VII highways. The project evaluates TTR metrics under various weather conditions (such as normal weather, rain, and snow), time of day (AM peak and PM peak), and global events like the COVID-19 pandemic. Out of the five TTR metrics, in general, INRIX measured the TTI, PTI, and LOTTR metrics with the most accuracy, compared to the ground truth data. In most cases, LOTTR was most accurately measured by INRIX. On the other hand, INRIX measured BI and COV with the least accuracy, compared to the ground truth data. One of the most notable findings from this project was whether the transportation system’s reliability increased or decreased or to what extent the reliability changed depended on which metric was used to measure it. Therefore, engineers and transportation agencies require a deeper understanding of the travel time related statistics and transportation system’s characteristics to understand the actual changes that occurred in travel time reliability.
Comments
Copyright 2024, the authors. Used by permission