Tracking Congestion in 2020 via FHWA’s Urban Congestion Trends Report
Travel on the Nation’s highways has changed substantially since the first automobile was invented by Karl Benz in 1885. Back then, the few cars that were in use shared roads with countless horses with carriages, bicycles, and pedestrians.
Today, our highways are flooded with cars, trucks, buses, and motorcycles. With more vehicles on the road, traveling safer and more efficiently takes time, funding, and planning. Measuring change in congestion levels and travel-time reliability plays a large role in those mitigation efforts and helps improve safety and efficiency on roads across the country.
The Urban Congestion Report (UCR) Program
The 2020 Urban Congestion Trends (UCT) report provides the results of three congestion- and reliability-related performance measures during the pandemic that began to affect travel in March 2020. The UCT is developed annually by the Federal Highway Administration’s Office of Operations to show trends in the year-to-year measures and provide examples of using the measures to better plan and operate the highway system.
FHWA’s UCR program began in 2005 and was started as a research project to determine if travel-time data existed to calculate congestion performance measures. The program used travel times culled from traveler information websites to calculate congestion and mobility performance measures. The reports soon became a proof of concept for transportation agencies as a way to use their traffic sensor travel-time data to calculate meaningful operations-related performance measures on their roads. Changes in the program over the years included using vehicle probe-based travel-time data and updating and improving performance measures, including focusing more on the travel-time reliability measure. These revised measures were included in many internal FHWA and U.S. Department of Transportation plans, budgets, and performance reports.
The UCR program currently produces a quarterly report using travel-time data on highways from 52 urban areas (those with over 1 million in population per the 2010 census). The travel-time data are obtained from the National Performance Management Research Data Set (NPMRDS), which provides data on the National Highway System for use by FHWA, as well as State departments of transportations (DOTs) and metropolitan planning organizations. The program also produces an annual UCT report that tracks annual performance measures from those same 52 urban areas.
The report also describes new approaches and tools for measuring congestion and related measures and shows examples of benefit evaluations of operational strategy implementation that help operating agencies manage congestion and improve mobility. Previous operational strategy examples in the UCT include freight operations, signal systems, ramp metering, and more. According to Bill Eisele, associate agency director at the Texas A&M Transportation Institute and author of previous UCT reports, “These performance measures assist in identifying congestion trends. Like getting your vital signs checked at the doctor’s office, using these state-of-the-practice performance measures is useful to identify if variations are systemic, or if they highlight a unique regional or local area change. These performance measures can also be a component of the decisionmaking process for implementing operational improvements (i.e., resource allocation).”
The current UCR program measures included in the report are as follows:
- Congested hours—The average amount of time (in hours) during a day when freeways operate in congested conditions. Congested conditions means when travel speed is at less than 90 percent of free-flow speed between 6 a.m. and 10 p.m.
- Travel-time index (TTI)—The time penalty for a trip on an average day. For example, a TTI of 1.30 indicates a 20-minute free-flow trip takes 26 minutes (20 × 1.30) during rush hours (weekdays 6 a.m. to 9 a.m. and 4 p.m. to 7 p.m.).
- Planning time index (PTI)—The time penalty for a trip to be on time for 95 percent of trips (e.g., late for work 1 day per month). For example, a PTI of 1.60 indicates a 20-minute free-flow trip takes more than 32 minutes (20 × 1.60) 1 day per month.
The free-flow speed is calculated as the 85th percentile of off-peak speeds, where off-peak is defined as Monday through Friday, 9 a.m. to 4 p.m. and 7 p.m. to 10 p.m., as well as Saturday and Sunday, 6 a.m. to 10 p.m. For the purposes of the UCR program, the free-flow speeds are calculated for each roadway segment grouping and are based on the previous 12 months of data.
52 Urban Areas Covered in the UCT
The 2020 UCT Report
The 2020 UCT report showed noticeable impacts of the recent pandemic on congested hours, TTI, and PTI. The effect of reduced travel in the 52 largest urban areas is evident in the accompanying graph that displays the congested hours measured monthly from 2019 through 2021. A drop of nearly 3 hours of congestion per day occurred in April 2020 compared with the average in 2019. While conditions were returning to prepandemic levels by the end of 2021, there was still roughly 30 minutes less congestion on average than in 2019.
For additional context, a key graph from FHWA’s Office of Highway Policy Information’s Traffic Volume Trends report shows the 2020 traffic volume estimates. The graph combines the 2020 data for congested hours and percent reduction in volume. The reduction in volume dropped in April 2020 by roughly 40 percent. The number of congested hours also dropped sharply in April, decreasing by nearly 3 hours, to about 1 hour on average from the prepandemic 3.5- to 4-hour daily average. The recovery of traffic volumes into the fall of 2020 approached 90 percent of prepandemic levels and then held steady. The congested hours measure also flattened out to around 2.5 hours a day on average.
The 2020 UCT report also includes an evaluation of the cost savings from the implementation of automated traffic signal performance measures by the Maricopa County DOT in Arizona.
Another highlight of the report is a tool developed by the Sacramento Area Council of Governments (SACOG) that assists with on-the-fly project assessment. Their project performance assessment tool helps evaluate congestion metrics and the reliability of a submitted road project. The tool uses NPMRDS speed and travel-time data to measure how reliable and congested a road is. The tool allows users to select average speeds or reliability metrics by time of day and presents the metrics visually on a color-coded map.
The 2020 UCT report showed noticeable effects of the pandemic on three travel-time measures. The correlation with reduced traffic volumes, easing congestion, and improved reliability was notable. The UCT report series demonstrates a number of ways that operational strategies can help reduce congestion, especially at the local or regional level. As congestion returns to near normal levels after the pandemic, the use of operational strategies to reduce both recurring and nonrecurring congestion and improve the efficiency of our highway systems will continue to be profiled in the annual UCT report.
In 2021 and 2022, the performance measures covered in the UCT reports continued to edge back to prepandemic levels. In the coming years, the UCT reports will continue to assess the impact of hybrid and remote work on commutes.
The SACOG performance assessment tool can be found at: https://www.sacog.org/project-performance-assessment.
Read the full 2020 Urban Congestion Trends report here: https://ops.fhwa.dot.gov/publications/fhwahop21010/index.htm.
Rich Taylor is the Operations Performance Measures and Management program manager in FHWA’s Office of Operations. He has three degrees from the University of Virginia.
Pete Koeneman is a research data scientist at the Texas A&M Transportation Institute and has a master’s degree in operations research from the Naval Postgraduate School.
For more information, see https://ops.fhwa.dot.gov/perf_measurement/reliability_reports.htm or contact Rich Taylor, 302-734-1657, firstname.lastname@example.org.