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Chapter 2, Coordinated Freeway and Arterial Operations Handbook

2. Planning for Coordinated Operation of Traffic on Freeways and Arterials

2.1 Purpose

The purpose of this chapter is to provide a broad view of the planning-level activities recommended for the successful development of CFA plans and procedures. Many of these planning-level activities should take place at a regional level before developing plans and procedures for a specific corridor. Collaboration and coordination among regional stakeholders on regional-level policies, agreements, operational strategies, and funding priorities will set the stage for successful corridor level plans and procedures. In addition, this chapter provides a corridor-level framework for the entire life cycle of planning, deploying, and operating plans and procedures for coordinated operations on a single corridor. Upon reading this chapter, the reader should have a good understanding of the importance and benefits of planning for CFA operations.

This chapter provides a top-down approach to the subject by first focusing on the regional-level planning and coordination activities recommended for corridor management and then introducing the corridor-level framework for corridor management. This corridor-level framework will be explained in more detail in the next chapter, chapter 3.

2.2 Introduction

While an agency could make the case for delving right into the development of corridor management plans and procedures, this chapter suggests that the chances for success will be much higher if some initial planning and coordination is done upfront. Further, the chances for success are even higher if this coordination and collaboration is first initiated at a regional level before filtering down to planning for a specific corridor. In terms of corridor management, taking a regional perspective means developing consensus among regional stakeholders through policies, procedures, agreements, strategies, and priorities for the entire region that will expedite the development of plans and procedures for individual corridors.

"Regional operations" means putting the available operations elements together into an integrated package that focuses on maximum system performance from the users' perspective. The critical integration elements among the regional stakeholders are:⁽⁹⁾

• Resource integration.
• Information exchange.
• Equipment sharing.
• Pooled funding.
• Personnel integration.
• Systems integration.
• Institutional integration.

The next section discusses the planning and coordination activities related to corridor management that should be done on a regional level. Section 2.4 introduces a system engineering framework for systematically developing and operating CFA plans and procedures for an individual corridor. The framework will be presented in more detail in the description of the corridor level framework in chapter 3.

2.3 Regional-Level Planning and Coordination

Today's realities require recognition of the constraints imposed upon further expansion of the highway network, particularly in metropolitan areas, and that maximization of system efficiency and system preservation need to become higher priorities. Regional planning for operations is a part of this new reality, and it must be assimilated into the broader metropolitan planning process undertaken by metropolitan planning organizations.

While local metropolitan policymaking organizations currently exist with their own local agency interactions and relationships, to achieve a broader vision of the transportation system requires building new processes and procedures with a regional focus. It is the regional transportation planning process that brings regional collaboration and coordination to bear on operational issues. This process provides a systematic approach to improving regional traffic management, a portion of which is corridor traffic management.

The first step in developing CFA operations is understanding that a corridor mindset requires a regional perspective and function. Figure 3 illustrates how certain functions can only be executed with cooperation and collaboration at the regional level, not at the local or individual agency level. Local agencies cannot achieve coordinated operations based on their individual actions.

Examples of regional functions include:

• Coordination between freeways and arterials operations.
• Coordination of traffic signals across jurisdictional boundaries.
• Sharing resources such as DMSs across jurisdictions.
• Joining traveler information systems among multiple agencies.

Figure 3. Chart. Relationship between regional and local functions.⁽¹⁰⁾

Regional-level focus provides multi-agency coordination for many aspects of the surface transportation system, fostering freeway mobility, arterial mobility, and traveler information. Regional coordination is also a primary factor in encouraging multi-agency sharing of data and resources.

Five major elements, shown in figure 4, form a collaboration and coordination framework on which to build sustained relationships between all affected agencies and stakeholders and create strategies to improve transportation system performance. The framework creates structures through which processes occur that result in products (e.g., a regional corridor traffic management plan as discussed in the next section). A commitment of resources is implied to support initiation and sustaining of regional collaboration and coordination and for implementing agreed upon solutions and procedures. The entire effort is motivated by a desire for measurable improvement in regional transportation system performance.⁽¹¹⁾

Figure 4. Chart. Elements of regional collaboration and coordination.⁽¹¹⁾

The objective of the collaboration and coordination framework is to help institutionalize working together as a way of doing business among transportation agencies, public safety officials, and other public and private sector interests within a region. The framework is therefore appropriate for developing a CFA operations program. Depending on the state of operations in the region, corridor operations can either build upon an established collaboration and coordination framework or the collaboration and coordination framework can be used as an aid to develop the interagency partnership necessary for a successful corridor operations program.

A collaboration and coordination framework is important because existing institutional structures create barriers that make collaboration and coordination difficult. These barriers include resource constraints, internal stovepipes in large agencies, and the often narrow jurisdictional perspective of governing boards. The framework is intended to guide operators and service providers in overcoming these institutional barriers by establishing a process that has been shown to be successful in facilitating cooperative relationships.

An example of developing a regional-level structure to overcome these traditional institutional limitations is shown in figure 5. This figure is from the Maricopa Association of Governments (MAG) Regional Concept of Transportation Operations, which provides the vision and goals for regional operations around Phoenix, AZ as well as a high-level view of the initiatives and performance improvements that collaboration and coordination may achieve. This figure shows the relationship between local and regional functions developed by the MAG for its region and is illustrative of how a regional focus was established using existing agencies. Note that a Freeway-Arterial Operations subcommittee has been established within this structure. This subcommittee organizes and coordinates the regional efforts for corridor management with the local agencies.

Another example of a regional-level structure is a regional operating organization (ROO), which consists of traffic operations agencies, transit agencies, law enforcement, elected officials, and other operations agencies focused on the operation and performance of a regional transportation system. A ROO works to ensure interagency coordination of resources and information across jurisdictional boundaries. It builds partnerships and trust among agencies to improve their productivity and performance, creating a more responsive system to temporary capacity deficiencies. ROO member agencies may, for example, share traffic signal timing plans, coordinate planned strategies and resources for managing travel, conduct public outreach, and participate in interagency training.

Figure 5. Chart. Example of integrating regional and local processes.⁽¹⁰⁾

2.3.1 Developing a Regional Corridor Traffic Management Plan

The first step in developing a corridor management plan is to leverage or build on the regional planning process. The goal of planning at the regional level is the development of a comprehensive plan for coordinating freeway and arterial operations throughout the region. Such a plan, developed or supported by key stakeholders in all affected agencies, would be more likely to gain the approval of key decisionmakers responsible for funding decisions in the region. Once funding and resources have been harnessed, plans and procedures for specific corridors can be developed.

The objective of a regional corridor traffic management plan would be to address issues and barriers related to coordinating freeway and arterial operations that are best dealt with at a regional level before developing and implementing specific plans, strategies, and procedures within specific corridors. In other words, it may be possible to solve a host of issues globally for an entire region rather than cause unnecessary repetition by addressing the issues individually for each specific corridor.

Operations issues that can be addressed and resolved at a regional level through policies, agreements, and plans include:

• Optimization and coordination of signals between agencies.
• Optimization and coordination of traffic signals and adjacent ramp meters.
• Altering freeway ramp meters during freeway and arterial incidents.
• Altering arterial signal timing during freeway and arterial incidents.
• Sharing data on incidents and traveler advisories.
• Sharing DMSs during various events.
• Developing regional route diversion plans during freeway and arterial incidents.

In addition to developing common regional-level operations policies, agreements, and plans, a regional corridor management plan could identify and address a number of other issues:

• Establish a regional working group comprised of key stakeholders and a champion to lead the group in being responsible for corridor management within the region.
• Develop the vision, goals, objectives, and performance measures for corridor traffic management in the region.
• Develop a regional corridor management concept of operations to identify high-level policies and plans needed to support plans and procedures for individual corridors (see the above bullet list for examples).
• Identify information and resource sharing needs on a regional level (e.g., identifying whether local agencies need to access and view freeway detector and closed circuit television (CCTV) cameras) for the purpose of corridor traffic management.
• Propose technology and ITS needs to support corridor traffic management at a regional level (e.g., identifying the need for an updated freeway transportation management center (TMC) software system that better allows for regional information and resource sharing).
• Identify and prioritize specific corridors that need corridor-level plans and procedures for CFA operations.
• Develop a plan for budgeting and phasing corridor-level studies and the subsequent design, implementation, operation, and maintenance of the individual corridor management plans.

The process of putting together a regional corridor management plan will be highly dependent upon existing programs and relationships among local agencies. Figure 5 in the previous section illustrates how one region created a region-based institutional structure that could be readily harnessed to develop such a regional corridor management plan. Each region will have to tailor their approach to the local institutional relationships and structures.

While a formal regional-level plan as suggested in this section is not a requirement before developing plans and procedures for individual corridors, there are benefits to developing a regional plan, such as:

• Resolving many of the institutional barriers on a regional level before proceeding to developing plans for individual corridors.
• Gaining region-wide consensus on the general approach and planning for corridor management in the region.
• Gaining the support of key decisionmakers responsible for funding decisions in the region.
• Cost savings through addressing regional operations issues just once rather than multiple times when developing plans and procedures for individual corridors.
• Cost and timesavings by early identification on what policies and agreements will be needed before proceeding to develop plans for individual corridors.

Some smaller regions may determine that the upfront cost of preparing a formal regional corridor management plan may outweigh the benefits listed above. For example, a region with one corridor that, both in the near- and long-term, would justify CFA plans, may not need a formal regional corridor management plan and could proceed directly to developing plans and procedures for that individual corridor.

After developing a regional corridor management plan, the region would have institutional structures in place, consensus by regional stakeholders, policies and plans to support corridor management, a prioritized list of corridors warranting individual plans, and the resources identified to develop and operate individual corridor implementation plans. The next section discusses a recommended framework for development and operation of individual corridor implementation plans and procedures.

2.4 Corridor-Level Planning and Coordination

A process roadmap, or framework, was developed to facilitate the life cycle (planning, design, operations, and maintenance) of CFA operations for an individual corridor. This framework is recommended for individual corridors after addressing regional-level issues identified in section 2.3. Because corridor traffic management is typically fragmented due to the institutional make up of the agencies involved in corridor traffic operations, the framework provides a process to overcome the institutional seams that inhibit coordination and collaboration.

The framework is scalable based on the complexity of the corridor and required operations strategies. For smaller corridors, some steps may not need to be formally addressed (e.g., a formal evaluation of operations strategies may not be necessary when there is only one feasible strategy). For larger, more complex corridors, formally going through each step in the framework may be necessary to ensure consensus is achieved by stakeholders, to provide a roadmap through the entire life cycle of the project, and to help to identify and address major problems before it is too late (i.e., already in the implementation phase).

The coordinated freeways and arterials framework is composed of the following elements (a graphical version of the framework is presented in chapter 3):

• Getting Started:
  • Step 1: Problem identification.
  • Step 2: Institutional considerations.
  • Step 3: Goals, objectives, and performance measures.
  • Step 4: Corridor concept of operations
• Decisionmaking:
  • Step 5: Corridor scenarios and operations strategies.
  • Step 6: Evaluation and selection of strategies.
  • Step 7: Corridor implementation plan.
• Implementation:
  • Step 8: Design and development.
  • Step 9: Deployment.
  • Step 10: Operations and maintenance.
• Continuous improvement:
  • Step 11: Continuous improvement.

It should be noted that the framework is cyclic, because the process often requires iteration between steps to resolve competing issues. For example, an operations strategy may be chosen for evaluation. Upon close consideration, the strategy may require more resources than are available, resulting in the reconsideration of alternative strategies more consistent with the available resources.

The steps in the framework are grouped into four categories: getting started, decisionmaking, implementation, and continuous improvement. The remainder of this section presents a high-level discussion of each of these four categories. The next chapter, chapter 3, discusses each of these steps in more detail.

2.4.1 Getting Started

Step 1 is to define the problem. This may occur either through a formal performance monitoring process that is part of a regional planning process or as the result of an obvious operational problem such as traffic backing up onto a freeway due

to an arterial traffic signal. The definition of the problem in the broadest sense should actually begin at the regional planning and coordination stage discussed in the previous section. At the regional level, problems are identified at a minimal level of detail as part of a planning and programming function. What may be a problem to one agency may not be a problem to another; therefore, it is important to discuss and gain consensus on the extent and severity of the problem to be addressed.

This is where Step 2 comes in, which is to assess institutional considerations. A CFA framework can create a bridge for agency structures to address an identified problem in a manner that all affected stakeholders can support. Part of overcoming institutional isolation is establishing a structure, such as a working group composed of various representatives from the affected agencies, early on to guide the entire process. The structure, whether an ad hoc group or formal committee, should consist of the broadest constituency of stakeholders possible. Participants should be representative of all agencies and parties involved in the planning, design, operation, or maintenance of the plans and procedures (e.g., planners, engineers, traffic managers and supervisors, TMC operators, and maintenance personnel), as well as those directly impacted by the plans and procedures (e.g., law enforcement, emergency services, transit operators, special event centers, and major employers). The size of the group should be commensurate with the size and complexity of the project. Overall, the success of the project is a direct result of the ability of a variety of institutions, agencies, and affected parties to gain consensus, have regular contact through meetings or other communication, and work within the context of other regional entities.

Once the structure for the stakeholders has been agreed upon and developed, it will be their responsibility to identify the goals, objectives and performance criteria for the corridor, step 3 in the process. Ideally, the goals and objectives established will be directly related to the problems identified in the first step. If the problem was identified broadly, it will be the responsibility of the stakeholder group to examine the problem and develop a more detailed assessment of its nature. The goals will be broad statements of the desired outcome once the problem is resolved. The objectives will be specific statements of what will be achieved in support of the goals (e.g., to reduce incident-related delays by 10 percent), and the performance measures identified will represent specific measurements that will be used to assess the goals and objectives (e.g., vehicle-hours of delay during the a.m. peak travel period). Performance measures should include metrics that users of the transportation system experience directly, such as traveltime between points.

Step 4 in getting started is to develop a corridor concept of operations. The corridor concept of operations is a document, either formal or informal, that provides a high-level, user-oriented view of operations in a specific corridor. It is developed to help communicate this view to other

stakeholders in this process, such as the interested public, and to solicit their feedback. The final document should describe the goals, objectives, and performance measures of the corridor agreed upon by the stakeholder group. It should also provide a description of the existing corridor conditions, geometrics and traffic control devices, operating practices and policies, and ITS technologies and capabilities. It should also describe at a high level the operational scenarios (the traffic conditions during a given operational deficiency) when strategies, plans, and procedures are needed and the high-level strategies that can address the problems during these scenarios.

2.4.2 Decisionmaking

Decisionmaking starts with step 5 and requires identification of detailed operations scenarios for the corridor, which allows the process to move toward the selection strategies. While an example of a high-level scenario may be a full closure of the freeway during an incident, a more detailed scenario would be a full closure of the northbound direction of the freeway from Mileposts 15 through 20 for more than 2 hours. Based on this scenario, a number of operations strategies should be identified that may mitigate this potential cause of congestion. The types of strategies that are appropriate within a corridor management context include:

• Traveler information—providing information to travelers through a variety of media, such as radio, television, Web sites, kiosks, telephone (511), highway advisory radio (HAR), and both fixed and portable DMSs. Most regions use at least one or more of these media, but often the information is not coordinated in a corridor- or systemwide perspective. An example of providing traveler information from a corridorwide perspective might be setting a DMS on a freeway that provides incident information on nearby arterial streets, or an arterial DMS that provides freeway congestion information. A proactive approach might include directions for alternate routes via DMS or trailblazer signs to guide motorists around an incident or bottleneck.
• Traffic management and control—coordinating traffic management and control devices, plans, and procedures is another effective way to optimize travel through a corridor. A primary example is coordinating traffic signals and/or ramp meter signals for movement throughout the corridor. Local agencies could develop pre-arranged signal timing plans that could be implemented quickly in response to freeway incidents. Adjustment plans for adjacent ramp meters could also be incorporated into operations plans. Reversible lanes offer capacity enhancement if directional movements allow. Vehicle type restrictions during peak periods may ease congestion. Suspending toll collection has proven effective on several major facilities when inordinate queues have formed. Access control within a corridor is another means of traffic management; activating turning restrictions along an arterial during an incident and changing ramp meter timing to restrict access, or even temporarily closing a ramp, are all examples of operations strategies to control and manage traffic.
• Shared information and resources—strategies to share information and resources across and within agencies can be very simple and effective, yet are often overlooked. Information sharing can be as simple as a telephone call, page, or an e-mail from a freeway TMC operator to a city engineer to provide incident notification. This notification enables the engineer to quickly activate a pre-arranged signal timing operations plan designed to alleviate congestion due to an incident. Another efficient strategy that would allow agencies to easily monitor conditions along adjacent roadways is sharing CCTV cameras among agencies. Other resources that could be shared include incident response equipment such as service patrols, wreckers, or portable DMSs.

While many strategies may be easily identified, Step 6 is to evaluate and select the most appropriate strategies for each scenario. The assessment of strategies can vary from simple, pragmatic assessments to detailed traffic microsimulation studies. The method used should be appropriate to the complexity of the alternatives and the cost of implementation. The evaluation criteria should also be representative of the goals and objectives of the local area.

The final step in the decisionmaking phase of the CFA operations framework, step 7, is to develop a corridor implementation plan, which provides all the information necessary to proceed with the implementation phase. The corridor implementation plan may be a formal document that represents the sum total of all the work that has been undertaken up to this point, summarizing the identified problems; the goals, objectives, and performance measures; the corridor concept of operations; and the selected operations strategies for various corridor scenarios. When describing operations strategies, details such as capital and operating costs, potential programming priorities and scheduling, infrastructure needs in support of the strategies, and descriptions of maintenance procedures and costs can help create a valuable blueprint for the remainder of the project.

2.4.3 Implementation

The implementation phase consists of design and development, deployment, and operations and maintenance. Step 8, design and development, translates each of the various projects included in the corridor implementation plan into executable project operations plans. Operations plans would be developed only at a high level in the corridor implementation plan, while in this step the individual operations plans would be fully developed. For example, the corridor implementation plan may identify a light diversion signal timing plan as an operations strategy. In the design and development stage, the exact signal settings in the timing plan would be determined, the specific individual(s) authorized to implement the plan would be identified, and details of how the plans would be implemented would be agreed upon. The design of needed infrastructure to support the operations strategies, such as deployment of an arterial DMS, would also be completed at this stage of the process. Any needed interagency operating agreements would also be finalized during this step.

Step 9, deployment, comprises the construction of infrastructure, signing interagency agreements, and "turning on" needed software or communications equipment. There could be many factors involved with a multi-agency, multifaceted deployment, so patience and dedication is necessary to ensure a successful project.

Step 10, operations and maintenance, is perhaps the most important in the process. Stakeholders whose primary responsibility will be to activate and operate operations plans should be involved early in the process of developing operating plans and procedures. These individuals will not only provide valuable insight into operations and maintenance processes, but also have a clear understanding of the roles and responsibilities of operations and maintenance personnel during the various scenarios. They will also be able to ensure that plans are operating at maximum efficiency and reliability.

2.4.4 Continuous Improvement

The continuous improvement process, reflected in step 11, is never ending. As the system is being operated and maintained, it must be continually monitored. The monitoring process determines whether the actual performance of the system matches the goals and objectives of the project. If the system is not solving the problem identified in Step 1, then modifications should be made to better address the problem. This is, in effect, another cycle of problem identification, identification of improvement strategies, evaluation, prioritization, design, deployment, operations, maintenance, and so on. More detail is given in section 3.13 on when iteration through the process is necessary, and to which step in the process iteration should occur. Without such a process, the corridor (and the overall system) will fail to perform at optimum effectiveness and efficiency.

2.5 Summary

This chapter presented a broad view of the planning-level activities recommended for the successful development of CFA operations. The planning process was examined at a regional level and then at a corridor-specific level. It is only after understanding these levels that meaningful corridor sensitivity and analysis can be initiated. The CFA framework introduced in this chapter, is described in more detail in the next chapter. Utilizing a consistent framework insures a repeatable, stepwise process. Thusly, process, appropriate technologies, and deployable solutions are the primary focus for the remainder of this document.

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