Traffic congestion cost the average American roughly 97 hours per year and $1348 per driver, according to mobility analytics company INRIX’s 2018 Global Traffic Scorecard. To reduce congestion and preserve the safety and efficiency of traffic flow, federal and local government agencies have adopted an Active Transportation and Demand Management (ATDM) approach to determine which traffic control methods and techniques are best for particular zones and areas.
What is Active Transportation and Demand Management (ATDM)?
ATDM primarily includes the following traffic management techniques, though there are other transportation modes and assets that can be implemented when required by traffic control needs.
- Active Demand Management (ADM): This aspect of traffic management focuses on using traffic data and technology to dynamically manage demand for road use, which could include redistributing travel to less congested times of day or routes, or reducing overall vehicle trips by influencing a particular mode of travel.
- Active Traffic Management (ATM): This part of traffic management involves dynamically managing traffic flow based on current traffic conditions and predicted traffic patterns. Where active demand management involves rerouting and optimizing road usage to prevent travel congestion. ATM influences the behavior of drivers through lane choices and operations.
- Active Parking Management (APM): This part of ATM optimizes the performance and utilization of parking facilities to reduce time spent searching for available parking spots.
What are the strategies within an active traffic management system?
- Adaptive Ramp Metering: This active traffic control method limits the number of vehicles that can enter the highway at any given time by using traffic signals at entrance ramps. This helps reduce traffic buildup and ensures a steady flow of vehicles on the highway.
- Adaptive Traffic Signal Control: Traffic signals are typically used to manage intersections, but they can also be used to help manage wider sections of roadways as well. By synchronizing signals and adjusting times for green lights, traffic engineers can help make sure that traffic flows more smoothly along heavily trafficked routes.
- Dynamic Junction Control: Also called lane control, this ATM technique involves managing the number of lanes available in certain sections of the road based on factors such as time of day and current levels of congestion. Lane use management allows roads to be optimized for both high-volume periods and times when traffic is light.
- Dynamic Lane Reversal or Contraflow Lane Reversal: This active traffic management method involves updating the direction of lanes in response to current anticipated traffic conditions, allowing capacity to match traffic demand throughout a given day.
- Dynamic Lane Use Control: This ATM method involves dynamically managing the opening and closing of lanes based on traffic congestion and flow. It also includes warning motorists of lane closures using Lane-Use Control Signals so they can safely merge into adjacent lanes without impeding the flow of traffic or endangering other drivers.
- Dynamic Merge Control: This active traffic management technique, also known as dynamic late merge or dynamic early merge, allows traffic to merge in areas where there are multiple lanes, such as an entrance ramp or a bottleneck. By allowing drivers to merge at different points along the road, it can help reduce the amount of time that cars spend waiting in line and help prevent buildup of traffic.
- Dynamic Speed Limits: A dynamic or variable speed limit system changes the maximum allowable speed limit depending on the conditions of the road, such as poor visibility or heavy traffic. This helps ensure that drivers don’t exceed safe speeds while still being able to maintain a reasonable flow of traffic.
- Part-Time Shoulder Use: This is also known as Hard Shoulder Running (HSR) or temporary shoulder use, and it is implemented during periods of peak congestion levels or in response to traffic incidents or other conditions as necessary.
- Queue Warning: This ATM strategy employs dynamic message signs and flashing beacons to alert motorists of queues and slowdowns ahead of them, which reduces the number of rear-end crashes and improves safety. These warning messages are dynamically adjusted according to the location and severity of the traffic congestion or traffic delays.
- Traffic Signal Preemption: Section 4D.27 of the MUTCD outlines how a green light may be requested and provided to emergency and transit vehicles when they approach a signal light. This type of signal preemption allows traffic of particular importance to move unimpeded through normal and pedestrian traffic.
By employing these active traffic control methods, roads can become safer and more efficient while reducing congestion and improving air quality in our communities. The use of ATM is becoming increasingly important as more vehicles hit the roads. By utilizing these tools, transportation professionals can help ensure that everyone has a safe journey no matter where they are going.
Examples of active traffic management
- Weather-Responsive Speed Limits: This ATM project used dynamic speed limits to implement weather-responsive speed limits in numerous counties located in Alabama, Arizona, Maine, Tennessee, Pennsylvania, and Wyoming. Read about Wyoming’s project here.
- Adaptive Ramp Metering: Cities like Los Angeles, California and Houston, Texas introduced adaptive ramp metering to allow for dynamic adjustments based on traffic growth, travel patterns, and weekend congestion over time. The Metropolitan Transportation Commission noted that freeway travel times decreased by over 30% in several counties where adaptive ramp metering was introduced.
- I-66 Active Traffic Management System: Located in northern Virginia, this project used several ATM methods to develop an active traffic management system along Interstate Route 66. Elements of this ATM system included dynamic lane use control, dynamic speed limits, hard shoulder running, merge control, and queue warnings. The devices employed included roadway sensors, lane control and speed limit signals, dynamic message boards, and traffic management center (TMC) algorithms and controls. According to a post-evaluation report, this ATM system improved weekday travel times outside peak periods by 2%-6%, though there was still some degradation during peak periods.
- I-70 West Rolling Speed Harmonization: In Silverthorne, Colorado, dynamic speed limits were introduced using roadway sensors, ramp meters, and law enforcement control. You can read about Rolling Speed Harmonization Sunday here.
- I-55 Bus On Shoulder Demonstration: In Chicago, Illinois, a project was set up that introduced hard shoulder running with the help of traffic control devices like roadway sensors and dynamic message signs. You can read more about this project here.
- Variable Speed Limits on I-270: In St. Louis, Missouri, dynamic speed limits were introduced with the aid of traffic control devices like dynamic message signs, dynamic speed limit signals, and roadway sensors. You can read more about this project here.
- Midtown in Motion: In Manhattan, New York, an adaptive traffic signal control system was set up with the aid of roadway sensors, dynamic message signs, and TMC algorithms and control systems. The result of this project included a 10% improvement in travel speeds and the awarding of a Smart Solution Spotlight from the Intelligent Transportation Society of America (ITS America). Read more about this project here.
- US 36 Express Lanes Project: This project took place between Denver and Boulder, Colorado and included dynamic messaging signs, express lanes (HOV, HOT, and BRT), and a commuter bikeway. It also included technologies like dynamic tolling, traveler information system, and an incident management system based on the ATDM approach. You can read more about it here.
- I-80 Integrated Corridor Mobility (ICM) Project: This project was located in the Bay Area of California, between the Carquinez Bridge and the Bay Bridge. It included adaptive ramp metering, HOV ramp metering bypass lanes, VSL and managed lanes, local street traffic signal timing coordination, bus priority, and a traveler information system. You can read more about this project here.
When you need traffic control, call Safety Network
By strategically employing active traffic control methods under the ATDM approach, roads can become safer and more efficient while reducing traffic congestion and improving traffic flow in our roadway systems. At Safety Network, we’re all about safe and efficient traffic, from our traffic signs and traffic control services to our work zone management and traffic equipment rentals. If you’d like to discuss your traffic control needs, give us a call or contact our team today!