CHAPTER 1

Setting the Stage for Active Traffic Management

Background

Recurring and nonrecurring congestion continue to increase on the transportation network in the United States, leading to longer delays, higher fuel consumption, greater environmental impacts, reduced productivity, and more crashes. Transportation professionals continue to work to address persistent congestion and safety concerns but recognize their inability to add capacity and enhance the safety of their networks quickly and cost-effectively. Thus, they rely on transportation systems operations and management strategies to mitigate mobility and reliability impacts. Over the past few decades, many success stories and advances in freeway management, arterial management, and regional coordination have emerged. Today, most agencies have detection levels and operational capabilities that would have been unimaginable 30 years ago, and these capabilities can be leveraged for a wide variety of approaches to improve mobility and safety. However, changing travel patterns, growing demand, changing traveler behaviors, limited resources, and increasing traveler expectations all require agencies to ask the following question:

“What is the next generation of systems operations and management strategies that can address these new challenges?”

Successful examples from Europe and deployments in the United States have spurred increased interest in active traffic management (ATM) strategies for potential implementation across the country. However, as transportation professionals consider these strategies, they face the following fundamental questions that must be answered quickly and efficiently to identify which strategies to advance.

• How can agencies incorporate ATM strategies into regional plans and optimize projects to meet regional mobility goals?
• What facilities or corridors are best suited for ATM strategies in the region?
• How can the available ATM strategies be analyzed?
• Does a combination of ATM strategies yield additive benefits?
• What are the potential benefits of ATM?
• What are the best ways to engage the public in the discussion about new operating strategies?
• What will select ATM strategies cost in the near and long term?

This chapter provides a quick guide to the topics covered in the remaining chapters and the format used throughout the document. The remainder of this chapter presents the following sections:

• Guide Overview. The goals and objectives for the document, the intent of the guide to advance the concept of ATM, the intended audiences, and information on how to use the guide.

• The ATM Context. A comprehensive view of ATM and its relationship to other operational concepts and strategies that work to address mobility and safety challenges.
• Components of ATDM. A description of the three major components of active traffic and demand management (ATDM) and how they are interrelated for a holistic approach to managing transportation across the trip chain.
• The Bigger Picture. A discussion on the relationship of ATM to critical transportation issues facing the profession.
• Remaining Chapters at a Glance. A quick guide to the major topics covered in each of the chapters and appendices.
• Chapter 1 References. A list of references cited within the chapter.

Guide Overview

The intent of this guide is to provide planning and evaluation guidelines to transportation agencies to aid in the identification of the appropriate path forward with ATM strategies suited to regional needs and characteristics. Agencies considering ATM will be able to identify appropriate performance goals and measures for planned projects and select ATM strategies to consider for those projects. They will also be able to select the appropriate analysis tool(s) to evaluate the likely impacts of those projects and plan for the collection of field performance data and its analysis for performance-based planning and operations. Additionally, they will be better prepared during the project development and implementation processes by knowing appropriate budgetary and staffing needs for ATM operations and maintenance and being aware of critical institutional factors that can either be instrumental to success or derail a project.

Agencies need beneficial information related to ATM in all areas and levels of transportation planning as well as resources that directly link the transportation planning and programming process with operations. The intent is to help agencies assess which operational strategies they might include in regional transportation planning that have the potential to provide the most benefit to their transportation network. Agencies also require resources that highlight the major attributes of candidate corridors to help determine if any ATM strategy or combination of strategies is suitable and appropriate, as well as how they can help an agency best respond to the mobility, safety, and environmental needs of the corridor and the broader community. This guide intends to deliver such resources to maximize the potential positive impacts of ATM across the country.

The Intended Audiences

The intended audiences for this guide include planning, design, and operations practitioners primarily involved in implementing and operating ATM strategies on freeways and arterial streets. Specific agencies include but are not limited to federal, state, and local planning and implementing agencies; metropolitan planning organizations (MPOs); DOTs; state, local, and regional toll and mobility agencies; transit agencies; municipalities; enforcement entities; maintenance and maintenance service entities; consultants; and any other stakeholder groups in a region who have a vested interested in the safety and mobility of the traveling public.

How to Use the Guide

The goal of this guide is to organize critical information related to ATM in a format that is practical and beneficial to the intended audiences. It is structured as a practical and easy-to-use reference document for transportation professionals at all levels and from a variety of backgrounds. It is not designed to be read from beginning to end; depending on their specific

Once the selected dynamic actions are implemented, the agency continues to monitor the system to determine the impacts of those actions. Continuing along the active management cycle, the agency then assesses performance and modifies actions accordingly (FHWA 2012d).

TSMO, ATDM, and ATM help target system reliability and work to extend the service life of the existing infrastructure in which agencies have invested significant capital (FHWA 2012d). This focus is synergistic with the directive of past federal legislation for agencies to meet the performance management goals for federal highway programs, including safety, congestion reduction, system reliability, freight movement and economic vitality, and environmental sustainability (FHWA 2012d). Furthermore, it complements the emphasis of the second Strategic Highway Research Program (TRB 2015) reliability research that provided foundational tools for transportation agencies to address system reliability. In short, TSMO, ATDM, and ATM can help agencies do more with the system they already have rather than immediately look to system expansion to address reliability challenges.

The active management cycle represents the fundamental concept of taking a dynamic approach to a performance-based process. It serves as the backbone of the ATDM philosophy and helps ensure that agencies are actively and proactively managing their systems to optimize their infrastructure investment. With ATDM, the transportation system is continuously monitored, and travel demand and traffic flow are actively managed. These activities work to influence traveler behavior using technology, tools, existing assets, and programs to achieve operational objectives to actively manage any part of the transportation system (FHWA 2023b). Agencies can deploy a single ATDM approach or multiple strategies to increase benefits across the entire system. Using technology, ATDM manages traffic flow and influences traveler behavior in real time to achieve agency-identified operational objectives.

Components of ATDM

ATDM incorporates three major categories of strategies to impact the trip chain: ADM, ATM, and APM. Figure 1-4 provides an overview of the influence of these components of ATDM on the various steps within the trip chain (FHWA 2015). As illustrated, these components often overlap in terms of influence and can be implemented together to optimize system performance. Furthermore, the implementation scale of these strategies can range from the regional scale to the corridor, facility, or site-level scale or can include a combination of facilities across the spectrum as well as the intersection between different levels of facilities, such as between freeways and arterials. The following sections provide descriptions and examples of ADM and APM as components of ATDM.

ADM

ADM is the ability to dynamically influence travel behavior and manage system demand in real time using information and technology (FHWA 2012a). ADM influences the initial stages of the trip chain to maximize the available choices for travelers with respect to destination, time of day, mode, and even route for a select trip. It includes strategies such as dynamic ride-sharing, on-demand transit, dynamic pricing and incentives, comparative multimodal travel times, and predictive traveler information. Examples of ADM deployments from across the United States are provided in Table 1-1. Additional information on ADM can be found on the FHWA ATDM website (FHWA 2023a).

APM

APM is the dynamic management of parking facilities to optimize the use of those facilities while influencing travel behavior (FHWA 2012b). APM includes strategies like dynamically priced parking, dynamic parking reservations, dynamic wayfinding, and dynamic overflow transit parking. The objective of APM is to provide technology-supported information and resources to travelers to influence their behavior related to parking. Parking information offered by APM can influence trip timing choices, mode choices, and parking facility choices at the end of the trip (FHWA 2023c). The strategies help optimize the use of parking facilities and have a positive impact on localized traffic flow by ensuring travelers have dedicated parking, which limits their circulation searching for spots.

Examples of ADM deployments from across the United States are provided in Table 1-2. Additional information on ADM can be found on the FHWA ATDM website (FHWA 2023c).

Table 1-1. Example ADM deployments in the United States.

SOURCE: Adapted from FHWA 2023a.

Table 1-2. Example APM deployments in the United States.

SOURCE: Adapted from FHWA 2023c.

ATM

ATM is the ability to manage recurrent and nonrecurrent congestion, both dynamically and proactively, on an entire facility based on real-time or predicted traffic conditions (FHWA 2012c). Focusing on trip reliability, ATM strategies maximize the effectiveness and efficiency of a facility while increasing throughput and enhancing safety. ATM strategies rely on the use of integrated systems with new technologies, including comprehensive sensor systems, real-time data collection and analysis, and automated dynamic deployment to optimize system performance quickly and, in some cases, without the delay that occurs when operators must deploy operational strategies manually.

When various ATM strategies are implemented in combination, they can work to fully optimize the existing infrastructure and provide measurable benefits to the transportation network and the motoring public. One of the benefits of these new systems is that they allow for the dynamic or real-time automated operation of traffic management strategies that more quickly respond to changing conditions as they occur. As shown in Figure 1-5, these strategies include but are not limited to adaptive ramp metering, adaptive traffic signal control, dynamic junction control, dynamic lane reversal, dynamic lane-use control, part-time shoulder use, queue warning, transit signal priority, and variable speed limits. The strategies listed here are those that are specifically described in this guide and form the foundation of the ATM concept. General information related to ATM is also included on the FHWA ATDM website (FHWA 2023d).

The expanding national interest in ATM brings to the forefront the need for information and guidelines on critical issues related to these strategies. However, it is important for agencies to recognize that ATM strategies are not just for large urban areas nor do they always involve high-cost deployments. Instead, ATM can be customized to the current levels of capability for an agency or region and can be flexible and scalable based on agency needs, existing infrastructure, and available funding. Existing investments in intelligent transportation systems (ITS) provide the foundation for ATM, and the availability of real-time information, emerging

real-time decision support models and systems, and enhanced communications interchanges can help agencies throughout their design, implementation, and operations activities (Kuhn et al. 2013).

The Active Management Continuum

As noted previously, active is the key operational descriptor of ATM. The inherent dynamic nature of ATM acknowledges the use of near-real-time information from the infrastructure, which allows an agency to manage and change the deployment as needed. Additionally, the active management of the system lies on a continuum that moves from straightforward time-of-day operations to a truly comprehensive and proactive approach (see Figure 1-6).

The four levels can be described as follows (FHWA 2023b):

• Level 1: Static—Strategy responses to variations in conditions are preset and updated based on the calendar (periodic review and update), policy, or law.
• Level 2: Reactive—Strategy responses change when an agency observes problems with the static plans; involves limited if any, real-time monitoring.
• Level 3: Responsive—Strategy adjustments occur in real time in response to changing conditions.
• Level 4: Proactive—Strategy responses are adjusted in anticipation of future conditions.

Additional detail on the specific characteristics of each stage for various ATM strategies is included in Chapter 2—“ATM Strategies.” As agencies consider ATM for their facilities, it is important to acknowledge that working with existing capabilities can be a great starting point for ATM strategy operations. As capabilities advance, the ability to actively manage an ATM strategy will advance as well. Furthermore, an agency does not necessarily need to be at the far end of the active management continuum to effectively implement an ATM strategy and realize safety and mobility benefits from the deployment.

ATM as an Enabler

As described previously, ATM is a set of strategies that enables agencies to accomplish their goals of improving transportation by (1) reducing congestion, (2) improving safety, (3) improving reliability, (4) increasing capacity without new construction, (5) increasing the efficiency of existing infrastructure, and (6) improving sustainability. By using technology and data to dynamically control traffic flow in the areas of mode choice, route choice, and lane/facility choice, ATM aims to maximize the use of existing infrastructure and forestall the need to build new capacity. This approach preserves scarce resources for addressing needs more immediately and typically at cost levels that allow for more widespread improvements compared to new construction.

When agencies consider the development cost of new construction, including the increasing challenges related to the acquisition of right-of-way, environmental impacts, and equity considerations, ATM is often the first and best choice for bringing rapid and cost-effective improvements to the system. ATM strategies are typically employed to enable the dynamic management of traffic flow on highways and major arterials using technology and data. This allows agencies and operators to respond in real time to changing traffic conditions and incidents on the road, which further increases safety and reduces congestion.

ATM and TSMO

ATM (and by association ATDM) with its active management approach is a component of the overall concept of TSMO. The guiding principles of regional TSMO are active, integrated, and performance-driven management and operations. The cyclical active management process noted previously also applies to TSMO. This approach to managing the transportation system represents the integration of multimodal, cross-jurisdictional systems, services, and projects to optimize the performance of the existing infrastructure (FHWA 2023g).

Key descriptors associated with TSMO include dynamic, predictive, proactive, performance-driven, continuously monitored, and supply-and-demand oriented. Given these aspects of TSMO, ATM clearly represents the active piece of the puzzle. TSMO is evolutionary, with agencies striving for higher levels of active management, integration, and performance. The implementation of ATM strategies within the TSMO context represents an opportunity to advance from static operations along the continuum to fully dynamic and proactive operations and management of transportation systems. Current practices of state DOTs with respect to developing and implementing TSMO plans indicate that critical elements that contribute to successful implementation include recognizing an agency organizational structure, identifying champions, implementing training activities, empowering key staff members, conducting public outreach, and working to support TSMO activities, all of which are institutional in nature (Kuhn et al. 2021). Key criteria that agencies typically use for selecting TSMO projects, including ATM strategies, include the ability to leverage a major capacity project to deploy a TSMO project and the use of systems-engineering-based procurement requirements.

ATM and Planning for Operations

As noted previously, ATM is a subset of strategies that fits within the broad practice of TSMO. To that end, TSMO is a key component of planning for operations that emphasizes regional collaboration and coordination with respect to transportation operations, management, operations considerations within the context of the transportation planning process, and linkages between these collaboration and planning efforts (FHWA 2013). The planning for an operations framework developed by FHWA provides the foundation for incorporating ATM (and the broader ATDM and TSMO) in various ways.

Transportation professionals and agencies at the state, regional, and local levels involved in transportation planning and investment processes work to identify ways in which ATM can be incorporated into these processes through collaboration and coordination to facilitate regional TSMO. They recognize that ATM should not be a project or a set of projects shoehorned into the planning process but rather a key element in planning and programming as a viable path toward optimizing system operations. The need for ATM emerges from the requirements to meet the regionally agreed-upon objectives in the planning process. Once objectives have been identified and agreed to, the approach to ATM strategy selection can become customizable to local priorities and constraints under which a corridor may operate. Thus, the relationship between ATM and TSMO creates the connection between ATM and the planning for operations framework.

ATM and ICM

Active management factors can be incorporated into the integrated corridor management (ICM) concept, as shown in Figure 1-7. ICM represents a suite of proactive approaches and strategies to address congestion and travel time reliability issues using multimodal solutions within specific travel corridors (Gonzalez et al. 2012), with ATM strategies being likely key

components of an ICM system. ICM is the management of a corridor as a single system rather than the more traditional approach of managing individual transportation networks (e.g., freeways, arterials, transit) (FHWA 2023f). Within the ICM context, multimodal operating agencies advance their respective system management and operations capabilities via active management. Agencies collaborate and cooperate to integrate their systems; share data and information; and provide coordinated, multimodal responses to optimize operations across an entire corridor and better manage congestion. ATDM (ADM, ATM, and APM) is a fundamental element of the active management of these systems within ICM.

Thus, as described in this section, ATDM and its active management foundation are an integral part of the approach to transportation development and operations. From the planning, programming, and investment decisions made by agencies to comprehensive TSMO and corridor-related ICM, ATDM, and ATM are essential to the future of transportation.

ATM on Arterials

Many of the ATM strategies covered in this guide apply to the arterial environment in addition to the freeway environment. For example, adaptive traffic signal control clearly applies to surface streets as does transit signal priority. However, both can also be critical components of an ICM deployment that addresses the relationship between managing the freeway and adjacent arterial facilities in concert with using several ATM strategies. Furthermore, part-time shoulder use can offer benefits to congested arterials where shoulders are available for use either by all vehicles or designated users, such as transit vehicles. Dynamic lane-use control and dynamic lane reversal are often used on arterials in response to directional volume imbalances or other conditions that can benefit from a temporary capacity increase, such as during special events or evacuation. The guide highlights arterial applications where appropriate to ensure the practitioner understands the breadth of potential applications and the critical issues associated with ATM in both the freeway and arterial environments.

ATM and Multimodal Transportation

Various potential benefits related to ATM could be realized by other modes beyond passenger vehicles. Some of these potential benefits may primarily benefit multimodal transportation, while others are secondary in that they benefit all system users. Thus, the potential benefits of each of the ATM strategies with multimodal applications are categorized as either primary (P) or secondary (S) benefits to the multimodal community. Table 1-3 shows the various ATM strategies and the primary and secondary benefits that each holds for multimodal transportation.

Primary benefits can be described as those that directly affect the performance of the multimodal application, such as reducing travel times, reducing intersection delay, increasing travel time reliability, and increasing travel speeds. Secondary benefits can be categorized as those that are attributed to safety, such as reduced crash rates and severity and reduced secondary crash incidents.

As illustrated in Table 1-3, the ATM strategies that have the most primary and secondary benefits for multimodal transportation [e.g., high-occupancy vehicle (HOV) and/or high-occupancy toll (HOT) lanes, transit, light-rail, or other modal applications for special users] include the following:

• Adaptive ramp metering.
• Separate lane/bypass lane.
• Adaptive traffic signal control.
• Dynamic junction control.

• Dynamic lane reversal.
• Dynamic lane-use control.
• Part-time shoulder use.
• Transit signal priority.
• Variable speed limits.

The Bigger Picture

In addition to improving daily operations on the network, ATM can play a role in addressing the larger challenges facing agencies, including safety, sustainability and resilience, and equity. The following sections provide a brief look at how ATM can support initiatives to improve transportation options for the traveling public and the impacts of the network on the quality of life for communities.

Relationship to Safety

ATM strategies are key tools in the operations toolbox that can offer important safety benefits to infrastructure owner-operators and the traveling public. Specifically, ATM strategies can help reduce primary and secondary incidents. By alerting drivers to congested conditions, promoting more uniform speeds, and temporarily modifying operations conditions to manage recurring congestion, the likelihood of primary incidents decreases. An informed driver is less likely to behave erratically when approaching congested conditions, thereby reducing their impact on the traffic stream. Likewise, alerting drivers to the presence of queues or incidents and proactively managing traffic in and around incidents reduces the likelihood of secondary incidents.

In addition to helping reduce incidents, ATM strategies can improve safety by enhancing the overall efficiency and reliability of the transportation network. Effective ATM operations can optimize the use of available resources, such as roadway capacity and transit services, to better accommodate the traveling public. This approach can reduce travel times, alleviate congestion, and minimize the likelihood of incidents caused by frustrated or aggressive drivers. ATM strategies can also improve safety by facilitating effective communication and coordination between different transportation agencies and emergency responders when ATM is deployed in response to an incident. By sharing information and coordinating response efforts, transportation agencies and emergency responders can more quickly and effectively respond to incidents and reduce the impact on traffic flow and safety. By leveraging advanced technologies and proactive strategies, transportation agencies can optimize the use of available resources, enhance communication and coordination, and provide real-time information to travelers to minimize the likelihood of incidents and improve the overall safety of the transportation network.

Many of the ATM strategies included in this guide are included in the Crash Modification Factor (CMF) Clearinghouse maintained by FHWA (FHWA 2023e). The clearinghouse is a web-based repository of CMFs for use by transportation professionals. Containing over 3,000 CMFs, the clearinghouse maintains information and resources related to using and developing CMFs. It serves as a search engine that allows users to search for CMFs for a specific countermeasure. The CMF Clearinghouse summarizes published information on each CMF, including its development characteristics (e.g., study design, sample size, and source of data) and its statistical properties (e.g., standard error). Where available, a link is provided to the publication from which the CMF was extracted. The CMFs are graded using a star rating based on five categories: study

• Appendix A—“ATM Terminology”: The glossary in this appendix provides a list of commonly used terms related to ATM as used throughout the guide.
• Appendix B—“ATM Strategy Fact Sheets”: This appendix includes a collection of fact sheets for each of the ATM strategies included in the guide.
• Appendix C—“Case Studies”: Detailed case studies for representative ATM deployments, which include an overview, key features, highlights, challenges addressed, outcomes and results, lessons learned, and future steps, are provided in this appendix.
• Appendix D—“Available Resources and Tools for ATM”: This appendix provides a list of recently published resources, including reports, guidelines, manuals, primers, and tools that can be used by transportation agencies to support ATM functions, covering a wide spectrum of areas involving organizing, planning, analyzing, modeling, programming, and budgeting for ATM strategies.
• Appendix E—“Planning and Evaluating ATM Checklists”: This appendix includes various checklists that agencies can use throughout the planning, development, implementation, and evaluation of ATM strategies.

Chapter 1 References