Traffic Signal Management Plans
Chapter 1. Purpose of this Guidebook
Research has shown that in effective traffic signal programs there is a strong connection between doing what's most important in the context of limited resources and the extent to which its activities are planned ahead to achieve specific objectives (FHWA, 2009). This research has shown that the extent to which an agency provides good service to its community is not necessarily directly related to the prevalence of resources. Some well-funded agencies are not high performers, while some agencies that are not well funded provide a high standard of service within their acknowledged constraints and in accordance with their plan. A common thread that exists amongst high performing agencies is a demonstrated ability to align and plan the design, operations, management and maintenance activities, and the ultimate replacement of traffic signals (NTOC, 2012).
This guidance establishes a framework for developing traffic signal management plans (TSMP) based on knowledge transferred from a number of archetypical traffic signal programs. A TSMP is intended to document and connect, at a high level, the goals, objectives, strategies and performance measures that an agency uses to achieve outcomes consistent with doing what's most important given a limited set of resources. This guidance will help practitioners strategically connect their activities related to traffic signal design, operations, maintenance, and management with the goals and objectives of their agency. The result will be an objectives-driven TSMP that:
Should You Invest Time in Developing a Traffic Signal Management Plan (TSMP)?
Ask yourself the questions in Figure 1. If you answer yes to any of them, your agency is a candidate for a TSMP.
It is clear from the results of the national traffic signal report card survey (NTOC, 2012) and other research that very few agencies have a comprehensive plan covering the full lifecycle of design, operations, management, maintenance and ultimate replacement of traffic signals. Moreover, those agencies that do have operating and management plans very often have not clearly linked their objectives to the livability and mobility goals and objectives of their agency or regional planning authority. A strategic approach is needed in order to effectively garner support for and resources to improve the state of traffic signal systems.
Based on FHWA’s broad experience with agencies across the country, it has also become clear that agencies that have some form of strategic plan that covers their traffic signal system also have a high level of performance in the management of their traffic signal system. Moreover, this seems to apply regardless of the level of resources available for traffic signal management. Many resource-rich agencies do not provide great service, while other relatively under-resourced agencies provide very good service within their constraints.
The TSMP connects the goals that appear in agency and regional plans with objectives and strategies that support day to day traffic signal design, operations maintenance, and administrative activities. The TSMP supports an agency's general plan or strategic plan, in a manner similar to an ITS plan, pedestrian master plan or a bicycle master plan, and lays the foundation for development of traffic signal capital improvement plans. Many agencies have existing procedures and policies that feed into the information in the TSMP. Figure 2 shows the relationship between the different documents an agency may have.
Good Basic Service and Program Reliability
The mission of a traffic signal program is to provide good basic service that satisfies the goals of the agency and regional partners involved in transportation systems management and operations (TSM&O). Good basic service is defined as doing the most important things given a set of resources. The definition of "important" is up to the agency to determine, but should match closely with user expectations. Traffic signal programs that do not align their objectives with agency and regional goals may encounter difficulty in attracting and sustaining resources to adequately design, operate and maintain traffic signal systems. Achieving good basic service requires implementation of strategies (operations, maintenance, and design) that work together to optimize the program, along with a clear understanding of their objectives. Figure 3 illustrates how the different aspects of managing a signal system all need to work together. If an agency is weak in one area, the stool will be unbalanced, meaning the other two areas need to compensate to remain balanced. For example, if detection is not maintained well, the signal will continue to operate, but the signal timing will need to be adjusted in order to serve the users. If an agency is not performing well in all three areas, the stool will collapse and good basic service will not be provided.
Program reliability is a measure of an organization’s ability to sustain good basic service. Sustaining good basic service is dependent on:
The TSMP connects the activities related to traffic signal design, operations, maintenance, and management with the goals and objectives of your agency. This will guard against the impacts of losing key staff, reductions in critical funding, or both.
Achieving good basic service will involve recognizing the interactions between the different actors, systems, and policies and procedures of your organization. Recognizing those interactions will help generate the appropriate mix of operational, maintenance, design and enabling strategies that agencies will need to keep the stool balanced. This concept is illustrated in Figure 4.
The Objectives-Driven Process
The TSMP is based on an objectives-driven, performance-based approach. This type of approach focuses on system performance to measure success rather than the number of activities implemented. The basis of this approach is the development of goals, context, objectives, strategies, and tactics (G-COST). The relationships between goals, objectives, strategies, and tactics are illustrated in Figure 5.
A goal is a broad statement that describes a desired end state. It is the "what" an agency is trying to achieve. Goals can address different aspects of the transportation system: reliability, efficiency, quality of service, preservation, etc. In many cases, the goal statements for a TSMP can be directly extracted from existing agency policy documents, such as a regional transportation system plan, related master plans such as bicycle and pedestrian master plans, and the transportation element of a city's general plan or master plan.
Here are some examples of agency goals:
While goals describe a desirable end state, they are not directly "actionable." That is the role of objectives.
While a goal can lead to many different objectives that may apply to a variety of activities (e.g., "livability" may be supported by transportation, libraries, parks, urban design and architecture, sports facilities, and landscaping), the administrative context of the plan and the physical context of the signal operation define the types of objectives that are appropriate in several ways:
An objective is more specific and measurable and is defined as "what" needs to be done in order to achieve a goal. Although in transportation planning, developing such aims has often been discussed together with goals (e.g., "developing goals and objectives"), it is important to make a critical distinction between goals and objectives within a performance-based planning and programming approach. Whereas goals relate to the "big picture" or desired end-result, objectives should be specific and measurable and support the achievement of a goal.
The most important aspect of identifying these overarching targets is that they be absolutely clear and "actionable." All objectives should include or lead to development of a performance measure that is able to validate achievement of the result, and to support decisions necessary to help achieve each goal. The aims of the TSMP may relate to multiple strategies within the traffic signal program in the areas of maintenance, design, management and operations.
Example TSMP objectives, extracted from some recent TSMPs include:
It is also important to clearly state the operational strategies one intends to employ in various situations, such as:
A strategy is defined as a capability put in place to achieve an objective. This is where you have the opportunity to be innovative, and also identify strategies that are achievable and sustained within your agency’s existing level of capability. Example strategies found in some recent TSMPs include:
Each of these strategies has a different effect on one or more of the following:
A tactic is the specific method to implement a strategy. It is an action taken (activities) or tool used to help implement the strategies in order to achieve objectives and attain goals. For example, in response to the objective of maintaining a high level of reliability in detection, these may be some appropriate strategies:
To implement these strategies, several entirely different tactics could be considered, which may include the following:
Each selected tactic has a different effect on one or more of the following and needs to be considered and either accepted or discarded:
It may be that each of these tactics will be applicable for an agency to use in one or other situations. For example, if an agency has a preference for standardization (often driven by a belief that maintenance will be more efficient if there is less variation in equipment and procedures), the real and perceived benefits of that standardization should be first weighed against foregone opportunities that would result from not picking the tactic that would most effectively address each situation.
At the end of the day, all your activities need to be documented so all relevant staff know exactly what they should do and when they should do it. Documenting activities encourages close examination of changes to procedures, ensuring changes represent improvements when they do occur. Ad hoc activities should eventually be formalized and documented, so for the purposes of the TSMP they should be included in an action plan to ensure they are enshrined in your agency’s procedures, are consistently implemented, and will not be lost or abandoned as key staff change.
United States Department of Transportation - Federal Highway Administration