Consider these questions
Why study traffic signal systems? Why are signal systems important to our nation's transportation system? What are the components of a traffic signal system and how does one prepare a design for these systems and their components? What standards are used by professionals in preparing these designs? How do traffic controllers work and how do the settings used in these controllers affect traffic flow? And, how do design teams effectively work together to prepare a design? You will be able to answer these questions for yourself as we work our way through this course during the next several months.
Why study traffic signal systems? Why are signal systems important to our nation's transportation system? What are the components of a traffic signal system and how does one prepare a design for these systems and their components? What standards are used by professionals in preparing these designs? How do traffic controllers work and how do the settings used in these controllers affect traffic flow? And, how do design teams effectively work together to prepare a design? You will be able to answer these questions for yourself as we work our way through this course during the next several months.
Consider these points
Our nation needs an efficient, safe, reliable, and secure transportation system. Our growing and migratory population relies on the efficient movement of people and goods from place to place. Efficiency means the shortest possible travel time and the least amount of energy expended. This efficiency depends, to a large degree, on proper traffic signal management: nearly two-thirds of all miles driven each year in the U.S. are on roadways that are controlled by traffic signals. In some urban areas, signals at busy intersections control the movement of more than 100,000 vehicles per day. And, 20 percent of the fuel used on urban arterials is expended by vehicles waiting at red lights! Poorly designed, inefficient, and uncoordinated signal timing results in a high cost from wasted time, inefficient use of precious energy resources, damage to the environment, and unsafe conditions for motorists and pedestrians.
You will find that traffic signal systems design is more than rocket science since it not only involves advanced technology but people as well: drivers who behave in different and sometimes unpredictable ways and elected officials who may not have a thorough understanding of all of the technical issues involved in traffic signal systems. You will be exposed to some of each during this course!
Our nation needs an efficient, safe, reliable, and secure transportation system. Our growing and migratory population relies on the efficient movement of people and goods from place to place. Efficiency means the shortest possible travel time and the least amount of energy expended. This efficiency depends, to a large degree, on proper traffic signal management: nearly two-thirds of all miles driven each year in the U.S. are on roadways that are controlled by traffic signals. In some urban areas, signals at busy intersections control the movement of more than 100,000 vehicles per day. And, 20 percent of the fuel used on urban arterials is expended by vehicles waiting at red lights! Poorly designed, inefficient, and uncoordinated signal timing results in a high cost from wasted time, inefficient use of precious energy resources, damage to the environment, and unsafe conditions for motorists and pedestrians.
You will find that traffic signal systems design is more than rocket science since it not only involves advanced technology but people as well: drivers who behave in different and sometimes unpredictable ways and elected officials who may not have a thorough understanding of all of the technical issues involved in traffic signal systems. You will be exposed to some of each during this course!
What you will do
You will have three primary tasks during this course:
You will have three primary tasks during this course:
- Build a knowledge base on traffic flow and control at signalized intersections.
- Determine the signal timing components for an actuated intersection and a coordinated system.
- Prepare a final signal timing design for each.
What you will be able to do (learning outcomes)
At the end of this course, you will be able to:
At the end of this course, you will be able to:
- Describe and apply a queuing model for traffic flow at signalized intersections.
- Describe a traffic control process diagram relating demand, detection, control, and display.
- Determine optimal values for actuated traffic control parameters for an isolated intersection.
- Evaluate the performance of an isolated signalized intersection using data derived from a microscopic traffic simulation model.
- Describe traffic flow along an arterial using a time space diagram, a platoon dispersion model, and data from a traffic simulation model.
- Determine optimal values for a coordinated traffic control systems.
- Prepare a written report and oral presentation summarizing the final signal timing plans for an isolated intersection and a coordinated signal system and the evaluation of these plans.
A Perspective from the textbook
The Approach
Our motivation in writing this book is to provide a learning environment and the necessary materials for a senior or graduate level university course in the design and operation of one important part of the traffic signal control system: the isolated intersection. We have made four assumptions that have guided the preparation of the material in this book.
Understanding the Traffic Signal Control System and the Traffic Controller
The traffic control system includes four interrelated subsystems or components: the user, the detector, the controller, and the display. Each component directly affects another component: for example, the detector responds to the user, while the controller responds to the detector. You will use tools that will allow you to visualize these relationships and more thoroughly understand them. The system and these components are more fully described and illustrated later in this book.
Creating an Active Learning Environment
If you learn to play the cello, you learn music theory. But most of your time is spent playing the cello: practicing and performing. Also, your cello instructor provides periodic (sometimes constant!) assessment of how you are doing: holding the bow correctly, placing your hand on the finger board, and listening to the quality of the tone that you produce. Educational research points to a hands-on active learning environment as the best approach to improving student understanding of important concepts.
Integrating What You See and Learn: Theory, Models, and the Real World
Learning to see the traffic system, to interpret and integrate what you see, to connect a model with what you observe in the field, and to understand the system and its operation, are all important attributes for a good traffic engineer. To help you in this process, you will be given a number of visualization tools: videos, simulation, charts, and figures. Study the ones that are provided to you and we will try to help you focus on their key points.
Understanding the System in Order to Design It
There is a logical design process that should be followed when preparing a signal timing design. Your learning process should provide an environment in which you can design components of the system and then test the design using a realistic simulation environment.
The Approach
Our motivation in writing this book is to provide a learning environment and the necessary materials for a senior or graduate level university course in the design and operation of one important part of the traffic signal control system: the isolated intersection. We have made four assumptions that have guided the preparation of the material in this book.
- You must understand the traffic control system and its component parts, especially the traffic controller.
- You should work in a learning environment with an activity-based learning approach, in which you learn by doing and observing.
- You need to learn to see, interpret, and integrate what you see. You also need to connect the theory that you learn with models that integrate the theory and connect both with what actually happens in the real world of signalized intersections and traffic flow.
- You must understand the traffic control system and its operation in order to design the system and its components. You need to have an understanding of the design process and gain experience in the application of this process.
Understanding the Traffic Signal Control System and the Traffic Controller
The traffic control system includes four interrelated subsystems or components: the user, the detector, the controller, and the display. Each component directly affects another component: for example, the detector responds to the user, while the controller responds to the detector. You will use tools that will allow you to visualize these relationships and more thoroughly understand them. The system and these components are more fully described and illustrated later in this book.
Creating an Active Learning Environment
If you learn to play the cello, you learn music theory. But most of your time is spent playing the cello: practicing and performing. Also, your cello instructor provides periodic (sometimes constant!) assessment of how you are doing: holding the bow correctly, placing your hand on the finger board, and listening to the quality of the tone that you produce. Educational research points to a hands-on active learning environment as the best approach to improving student understanding of important concepts.
Integrating What You See and Learn: Theory, Models, and the Real World
Learning to see the traffic system, to interpret and integrate what you see, to connect a model with what you observe in the field, and to understand the system and its operation, are all important attributes for a good traffic engineer. To help you in this process, you will be given a number of visualization tools: videos, simulation, charts, and figures. Study the ones that are provided to you and we will try to help you focus on their key points.
Understanding the System in Order to Design It
There is a logical design process that should be followed when preparing a signal timing design. Your learning process should provide an environment in which you can design components of the system and then test the design using a realistic simulation environment.