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Chapter 4: Moving Toward Active Traffic Management In The United States

Europe faces similar mobility challenges as the United States, including an increase in travel demand, growth in congestion, a need to improve safety, and the reality of limited resources to address these challenges. Given these similarities, the scan team recommends moving toward active traffic management in the United States to better manage congestion. While not a substitute for large-capacity expansion projects, active traffic management is a cost-effective means of prolonging the life and maximizing the efficiency of the infrastructure that can postpone the need for major expansions projects. It is also flexible enough to be implemented under temporary conditions in work zones and later be incorporated into the permanent operational infrastructure of a facility to extend the benefits to everyday operations.


The purpose of this scan was to examine the congestion management programs, policies, and experiences of other countries and to seek information on how agencies approach highway congestion and how they plan for and design managed lanes at the system, corridor, and project or facility levels. The following are the primary recommendations of the scan team in response to this charge:

Promote Active Traffic Management

Active management is the ability to dynamically manage recurrent and nonrecurrent congestion based on prevailing traffic conditions. Focusing on trip reliability, it maximizes the effectiveness and efficiency of the facility. It increases throughput and safety through the use of integrated systems with new technology, including the automation of dynamic deployment to optimize performance quickly and without the delay that occurs when operators must deploy operational strategies manually. When the combined operational strategies are implemented in concert, they fully optimize the existing infrastructure and provide measurable benefits to the transportation network and the motoring public. Potential benefits include increased throughput, increased capacity, decreased primary and secondary incidents, more uniform speeds, decreased headways, more uniform driver behavior, increased trip reliability, and the ability to delay the onset of freeway breakdown. For this reason, the scan team firmly believes that active traffic management is the next evolution in congestion management in the United States and that transportation agencies should promote and facilitate its implementation across the country.

Customer Orientation

A key component of active traffic management is the focus on customers and their needs. All of the operational strategies under the umbrella of active traffic management work to improve travel time reliability. They address the impacts of recurrent and nonrecurrent congestion while working proactively to prevent incidents that are major contributors to travel delays. While many of these strategies are not new to transportation professionals in the United States, their deployment in a coordinated and comprehensive manner within the framework of active traffic management represents a broader approach to addressing congestion by exhibiting a commitment to users and providing them with reliable travel times. They also signify the recognition of a link among incidents, their duration, and their impact on mobility for all users. Thus, customer reliability should be a critical gauge for all operational strategies as the United States moves forward with active traffic management.

Planning for Active Traffic Management

Whether to implement active traffic management and its operational strategies is a policy decision that must be made at the appropriate governing level. To that end, policymakers should develop both short- and long-range plans that incorporate active traffic management into the framework of transportation alternatives. Furthermore, agencies should approach active traffic management proactively by including it in current and future plans for target corridors. They should assess what active traffic management capabilities already exist in those corridors and what components need to be added to facilitate active management, even if conditions do not currently warrant such operational strategies. This forward-thinking approach will ensure that the infrastructure is put into place during future projects so that active traffic management can be implemented when warranted by congestion levels and mobility needs. In some regions, legislative support may be necessary to make this operational approach possible.

Operations Priority

In an era of limited resources, active traffic management is a significant drain on the limited funds an agency has available. However, it also represents an investment that should not be wasted so that its benefits can be realized. Thus, transportation and traffic management operations need to be a priority in the planning, programming, and funding processes for transportation. Legislation, policy, and financial resources are critical to the long-term success of active traffic management. Such resources help maintain and operate the system and ensure it adapts to new technologies to better serve customers. Thus, transportation agencies need to make the commitment to operations and make it a priority to maximize the benefits of infrastructure investment and to ensure sustainability and customer satisfaction through improved traffic operations.

Cost-Effective Investment Decisions

U.S. agencies constantly struggle to address growing congestion with increasingly limited resources and environmental restraints. The United States needs to develop tools to support active management investment decisions similar to those in use in Europe. These tools would help agencies conduct economic assessments of active traffic management by measuring the costs and benefits of its deployment in a corridor to determine project viability and economic effectiveness. The result would be a step-wise approach to assessing the best use of limited dollars to address critical congestion problems in a region.

Diverse Financing Strategies

The potential for diverse financing strategies to solve an ever-growing funding shortfall is significant. European success with PPPs in transportation has demonstrated the majority of benefits in operations and maintenance savings over the life of a contract. The inclusion of performance thresholds in the payment contract is essential to a successfully run project. Transportation-based performance measures tied to contract incentives include improved operations, reduced delay, fewer incidents, and other measures important to users. The result is a PPP that holds the concessionaire accountable for operations and ensures that the public entity spends resources with the best interests of users in mind. Thus, U.S. transportation agencies should pursue the feasibility of diverse financing strategies that meet funding needs while ensuring that customer needs and related performance measures are a priority throughout the life of the project.

Consistent Messages

As urban areas move toward active traffic management, there is a need to provide consistent messages to roadway users to reduce the impact of those travelers on congestion. The United States should adopt uniform symbology policies for active traffic management that resemble those used in Europe. Such uniformity would ensure that roadway users see the same symbols in Texas that they see in Minnesota, Virginia, or Washington.

Pricing and Managed Lanes

Road pricing for all users is being considered both in Europe and domestically as a smarter and more credible long-term option for maintaining the infrastructure. It ensures that users pay an appropriate share based on their roadway use, serves as a long-term solution to transportation finance shortfalls, and may also help with localized congestion management. However, it is only one component of a total management package and should not be seen as a cure-all for congestion problems.

In addition, active traffic management can easily support existing managed lanes strategies and incorporate new ones since active traffic management corridors are heavily instrumented and users are already familiar with dynamic operating conditions that reflect current congestion levels. Furthermore, managed lanes are a likely companion to active traffic management as they reinforce the efficient use and optimization of the existing network. Thus, managed lanes should be considered an operational strategy under the umbrella of active traffic management as part of the overall approach to managing congestion on U.S. roadways.

Active Traffic Management Strategies

Based on its observations, the scan team recommends nine strategies that members believe will move the United States toward comprehensive active traffic management to manage congestion. Table 3 outlines the potential benefits of these strategies, and the following sections present the critical components the team believes are necessary for successful and effective implementation. While some strategies are already used in regions across the country, it is the combined application of these strategies in a corridor that represents a cultural shift in the way transportation agencies operate freeways. Furthermore, these strategies can be applied to address both recurrent and nonrecurrent congestion to more effectively combat their impacts on trip reliability. Although these strategies are described individually, it is the combined, holistic application of the strategies for an entire network or region that will provide the most benefit.

Table 3: Potential benefits of active traffic management strategies.
Active Traffic Management Strategy Potential Benefits
Increased throughput Increased capacity Decrease in primary incidents Decrease in secondary incidents Decrease in incident severity More uniform speeds Decreased headways More uniform driver behavior Increased trip reliability Delay onset of freeway breakdown Reduction in traffic noise Reduction in emissions Reduction in fuel consumption
Speed harmonization X   X   X X X X X X X X X
Temporary shoulder use X X             X X      
Queue warning     X X X X X X X   X X X
Dynamic merge control X X X     X   X X X X X X
Construction site management X X             X   X X X
Dynamic truck restrictions X X       X   X X     X X
Dynamic rerouting and traveler information X   X X       X X     X X
Dynamic lane markings X X             X        
Automated speed enforcement     X   X X   X X     X X
Speed Harmonization

The United States should implement speed harmonization on freeways as a strategy to actively manage the network and delay the onset of congestion under normal operating conditions. The system should include the following elements:

Temporary Shoulder Use

Temporary shoulder use should be implemented where appropriate to temporarily increase capacity during peak travel periods. Specific elements of the operational strategy should include the following:

Queue Warning

Queue warning message displays should be implemented at regular intervals to warn of the presence of upstream queues based on dynamic traffic detection. Specific elements of the operational strategy should include the following:

Dynamic Merge Control

At merges from major interchange ramps, consideration should be given to dynamically metering or closing specific upstream lanes, depending on traffic demand. This could easily incorporate existing ramp metering systems and could offer the potential of delaying the onset of main lane congestion and balancing demands between upstream roadways. Specific elements of the operational strategy should include the following:

Construction Site Management

Agencies should undertake the strategic management of construction projects. Whenever possible, tools should be developed or existing ones used to assess the impacts of short-term construction projects on congestion and optimize the timing for such efforts. In addition, agencies should consider the use of active traffic management during a construction project to help offset the negative impacts of the work zone and to facilitate the permanent installation of active traffic management at the conclusion of the project.

Truck Restrictions

Truck restrictions implemented on a regional or national basis offer the opportunity to better segregate vehicles when implementing a variety of proactive lane management strategies that may not allow for safe operation in particular lanes. Specific elements of the operational strategy should include the following:

Dynamic Rerouting and Traveler Information

Dynamic rerouting and provision of reliable traveler information are critical components of a successful active traffic management system. They provide users with viable alternatives and are especially beneficial to reducing the impact of nonrecurrent congestion. Specific elements of the operational strategy should include the following:

Dynamic Lane Markings

Dynamic lane markings show promise in providing support to active management strategies, particularly temporary shoulder use. The possible applications of dynamic lane markings related to active management and their use in providing clear information to the driver should be explored fully to optimize their potential.

Automated Enforcement

Automated enforcement of speeds and other active traffic management strategies has the potential to ensure compliance with these strategies and their safe and effective operation to reduce congestion, the impact of incidents, and the impact of transportation on the environment. Specific elements of the operational strategy should include the following:

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Page last modified on November 7, 2014
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