Active traffic management

Active traffic management (ATM) includes a broad range of strategies for managing traffic dynamically based on current or expected conditions in order to improve the efficiency and safety of the transportation system. ATM strategies include ramp metering, variable speed limits, queue warning, and traveler information systems.

Key characteristics





WSDOT regions

Other names

  • Active traffic & demand management

Strategy description

ATM strategies improve the efficiency and safety of the transportation system through the use of technology that detects current conditions and responds automatically by communicating with drivers using ramp metering, variable speed limits, queue warning, or traveler information systems.

ATM strategies may include:

  • Corridor management - interagency coordination
  • Traffic management center (TMC)
  • Data synthesis & decision support
  • Dynamic lane assignment
  • Ramp metering
  • Variable speed limits
  • Variable message signs
  • Road weather information systems (RWIS)
  • Queue warnings

When to use this strategy

ATM strategies makes sense for:

  • Freeways or other major road networks that experience regular congestion
  • Specific locations with known issues, like high crash “hotspots”, construction or maintenance activities, bottlenecks (e.g., lane narrowing, sharp curves), or adverse weather
  • Areas in which new roadway construction is not feasible or desirable

Strategy benefits:

  • Reduces and better controls congestion
  • Maximizes the number of vehicles that can use a roadway
  • Delays the onset of congestion by allowing traffic to flow smoothly and efficiently
  • Environmental benefits through decreased emissions, fuel consumption, and noise
  • Improves safety through a reduction in crashes during congestion and weather conditions by adjusting traffic speeds and flow
  • Increased freeway volume and speed that reduces travel times for all vehicles
  • Low cost to install and maintain in comparison to more costly roadway expansions

What you need in order to implement

ATM comprises a broad range of strategies, each with their own implementation requirements. Refer to the related strategy links for more detailed information about each approach. In general, the following considerations apply to any ATM strategy.

Planning needs:

  • Operational analysis to determine appropriate ATM strategy or combination of strategies to address the traffic challenges
  • Systems engineering to describe the concept for the proposed system, how it will operate under a variety of scenarios, and the roles and responsibilities
  • Systems architecture to define how multiple traffic management systems will work together to deliver the desired outcome. This includes defining the data that the ATM system must collect and share with other traffic management systems. For example, an existing traffic data collection system may provide the traffic volume and speed data needed to set the variable speeds
  • Design analysis to confirm that the necessary roadway equipment can be located and operated in a safe and effective manner
  • Right-of-way acquisitions as required by the strategy (e.g., space for equipment poles and foundations)

Coordination needs:

  • Inter-agency coordination to develop policy, operations, and communications for ATM strategies across jurisdictions and/or systems
  • Law enforcement coordination to ensure driver compliance and address potential violations
  • Media and public outreach to provide education to users if the ATM strategies are relatively unknown. An example from the Oregon Department of Transportation is the ODOT RealTime information campaign (, which was shared with the media and the public prior to activating the system in order to enhance awareness, demonstrate the purpose, and explain how the ATM system would operate.

Agency resources needs:

  • Agency resources to monitor the functioning of the system and adjust its operation to maximize performance

About key characteristics

Location notes:

ATM strategies work best for corridors or primary routes because they are designed to manage speeds, warn about queues or incidents ahead, close lanes in advance of a lane-blocking crash, and provide travel times from one point to another.

Cost notes:

Investment in ATM strategies is high because it typically requires new overhead sign structures for lane control and variable speed signs mounted over each lane. However, compared to  major roadway widening projects that would be considered as an alternative, ATM is a lower cost solution.

Technology notes:

The technology needed for ATM is high because it requires electronic signs, sensors that measure traffic volumes and speeds, road weather sensors, monitoring cameras, ramp meters, and a sophisticated central software to manage the application.

Collaboration notes:

Collaboration with other traffic agencies is relatively low because ATM can be implemented as a freeway-only solution. However, the traffic agency must collaborate with law enforcement if the variable speed system is going to be enforced. Collaboration with traffic agencies increases when ramp meters are planned because traffic may back up onto the local streets and the installation should be coordinated with the local traffic agency.