Active Traffic Management for Congestion
Introduction
Traffic congestion is a major problem for Americans, causing travelers to waste countless precious hours getting to their destinations. In 2024, the average American driver was estimated to have lost an average of 63 hours each year to congestion while commuting [1]. Overall, congestion delays totaled 8.8 billion hours of travel delay [1]. Impacts of congestion are felt in many ways. Hours spent stuck in traffic interfere with time spent with family and friends. Freight and consumer deliveries are also delayed as trucks are stuck in congestion, resulting in higher costs. Critical emergency services can also be delayed by the additional time spent in traffic, putting lives at risk.
The Federal Highway Administration (FHWA) publishes several annual indices highlighting the effects of congestion.
Hours of Congestion: the amount of time when freeways operate at less than 90 percent of free-flow freeway speeds.
Travel Time Index (TTI): the time penalty for a trip on an average day. A TTI of 1.30 indicates that a 20-minute trip in free-flow traffic conditions takes 26 minutes, or 30 percent longer.
Vehicle miles traveled (VMT) have steadily increased over the past five years as millions of Americans return to the office and plan to travel, fueling mounting congestion and a need for innovative intelligent transportation systems (ITS) solutions to address the problem. The following charts show these trends over time. Despite a dip in 2020, congestion hours and TTI moved upward through 2024 and is expected to continue to trend upward as additional data become available.
FHWA Congestion Trends, 2012-2024
Source: FHWA Annual Urban Congestion Trends and Related Reports
FHWA compiles congestion hours quarterly for the largest metro areas in the United States. Explore the map below to see the amount of and changes to congestion since 2017, using Quarter 2 as a basis for comparison. Several metro areas, particularly in the southeast and lower Midwest, are currently experiencing more congestion than in 2017, on the order of a 10 to 20 percent increase.
FHWA Change in Congestion by Metro, Q2 2017-Q2 2025
Source: FHWA Annual Urban Congestion Trends and Related Reports
How Active Traffic Management (ATM) Can Help
Active Traffic Management (ATM) strategies provide agencies with the ability to dynamically manage recurrent and non-recurrent congestion based on prevailing and predicted traffic conditions [2].
ATM is comprised of several ITS technologies that can contribute to easing congestion either as standalone solutions or by being integrated into larger solutions. Common ATM technologies deployed for addressing congestion include:
Adaptive Signal Control Technology (ASCT)
Transit Signal Priority (TSP)
Dynamic Lane Use Control
Variable Speed Limits (VSL)
Adaptive Ramp Metering
Queue warning
ASCT 
This technology continuously monitors arterial traffic conditions and queuing at intersections and dynamically adjusts the signal timing to optimize one or more operational objectives (such as minimizing overall delays) [2]. | TSP 
This technology manages traffic signals by using sensors or probe vehicle technology to detect when a bus nears a signal-controlled intersection, turning the traffic signals to green sooner or extending the green phase, thereby allowing the bus to pass through more quickly [2]. |
Dynamic Lane Control (Dynamic Shoulders) 
This technology involves dynamically closing or opening of individual traffic lanes as warranted and providing advance warning of the closure(s) (through the use of lane-use control signals), in order to safely merge traffic into adjoining lanes [2]. | VSL 
These systems adjust speed limits based on real-time traffic, roadway, and/or weather conditions [2]. |
Adaptive Ramp Metering 
These systems consist of deploying traffic signal(s) on ramps to dynamically control the rate at which vehicles enter a freeway facility [2]. | Queue Warning 
These systems involve real-time displays of warning messages (typically on dynamic message signs and possibly coupled with flashing lights) along a roadway to alert motorists that queues or significant slowdowns are ahead, thus reducing rear-end crashes and improving safety [2]. |
To learn more about these technologies, visit the Spotlight on Active Traffic Management.
USDOT and FHWA Programs to Support ATM Adoption
Several U.S. Department of Transportation (USDOT) and FHWA grant programs have supported projects facilitating ATM strategies for congestion mitigation. Recent programs include:
Advanced Transportation Technologies and Innovative Mobility Deployment (ATTAIN): This program provides funding to deploy, install, and operate advanced transportation technologies to improve safety, mobility, efficiency, system performance, intermodal connectivity, and infrastructure return on investment. Grant recipients may use funds for technologies such as advanced traveler information systems, advanced transportation management technologies, and technologies to improve emergency evacuation and response [3].
Strengthening Mobility and Revolutionizing Transportation (SMART): This program provides grants to eligible public sector agencies to conduct demonstration projects focused on advanced smart community technologies and systems to improve transportation efficiency and safety [4]. Projects must leverage one of eight technology domains, including connected vehicles, intelligent sensor-based infrastructure, and smart technology traffic signals [5].
Congestion Relief Grant Program: This program advances innovative, integrated, and multimodal solutions for congestion relief in the most congested metropolitan areas of the United States with urbanized area populations greater than 1,000,000. The goals of the program are to reduce highway congestion, reduce economic costs associated with that congestion, and optimize existing highway capacity and usage of highway and transit systems [6].
Advanced Transportation and Congestion Management Technologies Deployment (ATCMTD) Grant Program: This program issued grants for the development of model deployment sites for large scale installation and operation of advanced transportation technologies to improve safety, efficiency, system performance, and infrastructure return on investment. Specifically, grant recipients could use funds to deploy advanced transportation and congestion management technologies [7].
ATM Technology Adoption
ATM technology has seen a steady increase in the adoption rate from 2016 to 2023 according to the ITS Deployment Tracking Survey. The survey, conducted approximately every three years, measures the deployment of ITS among freeway, arterial, and transit management agencies in a subset of large metropolitan areas across the United States.
For arterial management (AM) agencies, which includes State Department of Transportation (DOT) districts and local AM agencies, ASCT and VSL had a steady increase in adoption from 2016 to 2023 with total adoption increasing respectively by 8.8 percent and 9.5 percent. Freeway management (FM) agencies, which include State DOT districts and toll authorities, also experienced an increase in adoption for ramp metering and queue warning systems, with an increase of respectively 7.5 percent and 5.8 percent. Some technologies experienced growth in deployment between 2016 and 2023, despite a noted decline in 2020, including queue warning systems (AM) and VSL (FM).
ITS for ATM Adoption Rate 2016-2020 Source: USDOT ITS Joint Program Office (JPO) Deployment Statistics |
Highlighted Use Case Studies
ATM case studies of deployments and simulations in Arizona, Massachusetts, Michigan, Pennsylvania, Ohio, and North Carolina demonstrate how ITS can be applied in ways that lead to quantifiable benefits in addressing congestion challenges.
Adaptive Signal Control (Arizona):
A multi-agency partnership led by the Arizona DOT and Maricopa County DOT established a pilot program to investigate the promise of ASCT in enabling both operational cost savings and travel time savings in metro Phoenix. The Bell Road Corridor, which was highly congested and served multiple cities, was selected as a pilot to test different ASCT systems. The study found that in the four project areas where ASCT was implemented, there were weekday travel time savings up to 51 percent, with 3 of 4 project areas showing decreases in both weekday and weekend travel time. You can learn more about this case study in the Benefits, Costs and Lessons Learned Database. | Weekday Travel Time Savings following Implementation of Adaptive Signal Control Source: Arizona DOT |
Transit Signal Priority (TSP) (Massachusetts):
In 2023-2024, the Massachusetts Bay Transportation Authority in the Boston area implemented TSP aiming to improve travel times for the agency’s bus routes. Development of the system began in 2023, and the proof-of-concept test started in July 2024, with three intersections selected along Brighton Avenue. Since implementation, buses traveling through the corridor spent 21 percent less time waiting at red lights on average, leading to 8 percent faster travel times along the corridor You can learn more about this case study in the Benefits, Costs and Lessons Learned Database. |
Dynamic Shoulder Lane (Michigan):
In 2017, the Michigan DOT deployed an ATM system with a dynamic shoulder lane on U.S. Route 23 near Ann Arbor to help mitigate peak hour congestion. Results found that maximum throughput in the northbound and southbound direction increased by 11.0 percent and 35.4 percent, respectively. During peak periods, travel times decreased on average by 16.5 percent in the southbound direction and by 11.2 percent in the northbound direction You can learn more about this case study in the Benefits, Costs and Lessons Learned Database. | Decrease in Time and Increase in Maximum Throughput after Implementation of a Dynamic Shoulder Lane Source: Michigan DOT |
Queue Warning (Pennsylvania):
In 2024, the Pennsylvania DOT implemented a virtual queue protection queue warning system on roadways in any area where changeable message signs (CMS) were present. When detected speeds drop below a certain threshold, queue warning messages are automatically posted to upstream CMS boards along the corridor. From this deployment, those traveling through this zone saved 109,088 person-hours of travel time in the year post-activation, including 10,075 hours of travel time savings for trucks. You can learn more about this case study in the Benefits, Costs and Lessons Learned Database. |
VSL (Ohio):
In 2018-19, the Ohio DOT installed VSLs along a 12-mile stretch of Interstate 90 near Lake Erie to improve the safety of the corridor. Speed limits can be dynamically changed depending on different weather and road conditions. In addition to safety benefits, the deployment reduced incident clearance times by 31 minutes, aiding in a faster return to traffic flow, and overall user travel delay was reduced by an estimated 83 percent You can learn more about this case study in the Benefits, Costs and Lessons Learned Database. |
Ramp Metering (North Carolina):
In 2017, the North Carolina DOT installed four ramp meters along Interstate 540 and commissioned a study to measure the operational impacts of the signals. The signals were operational during morning rush hours Monday to Friday, from 6:30 AM to 9:00 AM, with 6 routes studied for impact. The study found that, after implementation, 84 percent of commuters experienced shorter drive times, with drive times after implementation decreasing on all of the hypothetical routes for 3 of the 5 days studied You can learn more about this case study in the Benefits, Costs and Lessons Learned Database. | Change in Commute Time after Ramp Meter Installation Source: North Carolina DOT |
Benefits
Benefits of ITS deployments are recorded and stored in the ITS Benefits database, part of the larger Benefits, Costs, and Lessons Learned (BCLL) databases maintained by the ITS Joint Program Office (JPO). The ITS Benefits database contains records on the benefits of ITS according to goals identified by the U.S. Department of Transportation, such as safety, mobility, efficiency, productivity, and customer satisfaction.
The following examples of ATM ITS benefits are among the many ITS Benefits located in the Benefits section of the BCLL database.
ITS Costs
Costs of ITS ATMS deployments are recorded and stored in the ITS Costs database, part of the larger BCLL databases maintained by the ITS JPO. A few examples of the costs related to ITS deployments in work zones are highlighted below.
The Total Capital Costs of a Dynamic Shoulder System on US-23 near Ann Arbor are Estimated at $60 Million. You can see the visualized costs broken out in the graphic on the right. (2022-SC00512). Estimated Cost for Implementing Max-Pressure Adaptive Signal Control on 3,280 Intersections in the Twin Cities Metro Area in Minnesota was $69,961,900.(2023-SC00536). Overall Cost to Implement Adaptive Signal Control Technology in Florida Ranged from $30,000 to $96,400 per Intersection.(2021-SC00484). In North Carolina, a Ramp Metering System at Four Entrance Ramps on I-540 Was Projected to Cost $1,655,560 over A Ten-year Period (2017 to 2027). (2022-SC00507). An Active Traffic Management (ATM) system covering 12.4 miles of I-66 in Northern Virginia cost $39 million (2018-SC00403). | Dynamic Shoulder System Cost Source: USDOT ITS JPO Cost data adjusted to 2020 dollars. |
In-Depth Case Study
Maryland DOT Implementing ATM Technology Along U.S. Route 50
Background
In 2023, the Maryland Department of Transportation (MDOT) was awarded an ATTAIN grant for a series of traffic technology enhancements. The Rural Opportunities to Use Traffic Technology Enhancements (ROUTE) on U.S. Route 50, called ROUTE 50, is an innovative and unique approach to dynamically managing traffic. ROUTE 50 focuses on improving safety, travel time reliability, mobility and quality of life. The deployments will take place along a 113-mile stretch of the U.S. Route 50 corridor in the state that links the oceanside resort towns of the Eastern Shore with the Washington, D.C./Baltimore region. Congestion between the two areas leads to impacts on mobility, emergency response times, freight and farm-to-market deliveries, and overall economic development [8].
Technologies
As part of the ATTAIN grant, MDOT is deploying a series of ATM-related technologies, among other ITS technologies, to the corridor to focus on alleviating the congestion challenges. Some of these technologies are listed below:
ASCT: MDOT is deploying ASCT for improving gridlock in the small communities along U.S. Route 50. Several different strategies will be used in collaboration with ASCT, depending on the specific characteristics of the congestion.
Decision Support System (DSS) with Machine Learning (ML) Prediction: assess and predict conditions during high congestion periods and support ATM applications such as ASCT to ensure optimal flow of traffic.
Incident Response Signal Timing plans would be used during major incidents to more readily direct traffic to alternative routes.
Quality of Life and Queue Management (Q2) Inverse Traffic Responsive Pattern Selection (TRPS): This signal system will reduce queues at the Bay Bridge to limit backups to the local road network and out of the communities of Easton and Cambridge. It is a DSS that ingests region-wide traffic sensor data in real time with an ML traffic prediction system that supports dynamic, or adaptive, traffic signal behavior.
Connected Vehicle (CV) Systems for Signal Phasing and Timing (SPaT): MDOT is incorporating SPaT to enable future CV applications, such as Freight Signal Priority, to help address congestion issues.
Traffic Sensors: CCTV, Volume & Speed Detectors, Origin-Destination & Travel Time Detectors: MDOT is installing sensors to measure real-time traffic data to provide situational awareness to the Transportation Management Center (TMC), feed the ML Traffic Prediction System, provide information to travelers, and implement traffic management plans, Integrated Corridor Management, and Decision Support System.
Source: MDOT Alternative Route Travel Time Information Signs & Dynamic Message Signs: MDOT is deploying both types of signs, pictured on the right, at key decision points throughout the corridor.
Estimated Benefits
MDOT estimated quantifiable mobility benefits for several of these technologies along the U.S. route 50 corridor, which can be seen in the table below:
| Technology | Annual Improvement | Annual Benefit |
| Travel Information | 552,434 hours | $10,910,128 |
| ASCT | 12,439 hours | $245,670 |
| Q2 TRPS: US 50 | 267,897 hours | $5,290,953 |
| Q2 TRPS: Side Street in Towns | 1,066 hours | $21,054 |
To learn more about this project, read the full report: Rural Opportunities to Use Traffic Technology Enhancements (ROUTE) on US 50
Additional Resources
| Resource | Description |
| Texas Transportation Institute (TTI) Urban Mobility Report | Report conducted annually by TTI that measures congestion by using crowdsourced data from INRIX on urban streets and highways, along with highway inventory data from a Federal Highway Administration database. |
| FHWA Active Traffic Management | Resource showcasing ATM technology definitions as well as links to real-world deployment examples. |
References
[1] D. Schrank, L. Albert, K. Jha and B. Eisele, "2025 Urban Mobility Report," Texas A&M Transportation Institute, College Station Texas, 2025.
[2] "Active Traffic Management," FHWA, August 2023. [Online]. Available: https://ops.fhwa.dot.gov/atdm/approaches/atm.htm. [Accessed November 2025].
[3] "Advanced Transportation and Congestion Management Technologies Deployment," UDOT, [Online]. Available: https://www.transportation.gov/rural/grant-toolkit/advanced-transportation-technologies-and-innovative-mobility-deployment. [Accessed November 2025].
[4] "Smart Grants Program," USDOT, August 2025. [Online]. Available: https://www.transportation.gov/grants/SMART. [Accessed November 2025].
[5] "Funding Innovation through the SMART Grants Program," USDOT Volpe Center, July 2024. [Online]. Available: https://www.volpe.dot.gov/news/funding-innovation-through-smart-grants-program. [Accessed November 2025].
[6] "Congestion Relief Program," FHWA, September 2025. [Online]. Available: https://www.fhwa.dot.gov/infrastructure-investment-and-jobs-act/congestion_relief.cfm. [Accessed November 2025].
[7] "Advanced Transportation and Congestion Management Technologies Deployment," FHWA, February 2017. [Online]. Available: https://www.fhwa.dot.gov/fastact/factsheets/advtranscongmgmtfs.cfm. [Accessed November 2025].
[8] "Rural Opportunities to Use Traffic Technology Enhancements (ROUTE) on US 50," Maryland Department of Transportation (MDOT), 2022.
