**National Transportation Curriculum Project**

In 2009, as a result of a conference on transportation education held in Portland, Oregon, a group of university transportation faculty initiated the National Transportation Curriculum Project (NTCP). The purpose of this project is to develop a new set of curricular materials for the introductory course in transportation engineering that are based on principles of active learning, focusing on a clear set of learning objectives, and with connections to how practicing professionals conduct their work. The project has spawned a number of technical papers, workshops, research projects, and new curricular materials in topic areas commonly taught in this course, including traffic operations, geometric design, and transportation planning, among others.

**What Students Learned...and Didn't**

As part of the NTCP, in 2011, we began a study of what students learned (or didn’t learn) about signalized intersections in the introductory transportation course. We analyzed examination results, homework assignments, and interviews with students to identify concepts that were particularly difficult for them. We reviewed existing textbooks commonly used in the introductory course to identify how concepts and topics related to signalized intersections were treated. We also reviewed standard guidebooks used by transportation professionals to identify concepts that would be appropriate to include in a new curriculum.

From these data, we developed a set of learning objectives that would govern the development of a new curriculum on signalized intersections that could be taught in the introductory course in transportation engineering. This book is the first product of that work. Additional materials such as critical thinking exercises, classroom activities, and design projects are being developed and will be distributed at a later date. Other related materials such as ranking tasks have been developed by other research teams.

**Sequence of Concepts**

The sequence in which concepts are presented in this book, and the way in which more complex ideas build on the more fundamental ones, was based on our study of student learning in the introductory course. The development of each concept leads to an element in the culminating activity: the design and evaluation of a signal timing plan in section 9. For example, to complete step 1 of the design process, the student must learn about the sequencing and control of movements, presented in section 3 of this module. But to determine split times, step 6 of the design process, four concepts must be learned including flow (section 2), sequencing and control of movements (section 3), sufficiency of capacity (section 6), and cycle length and splits (section 8). Depending on the pace desired by the instructor, this material can be covered in 9 to 12 class periods.

- Overview of Intersection Operation and Control
- Representing Traffic Flow at a Signalized Intersection
- Sequencing and Controlling Movements
- Yellow and Red Clearance Intervals
- Capacity
- Sufficiency of Capacity
- Delay and Level of Service
- Cycle Length and Split Times
- Signal Timing

**Guidelines for the Development of the Book**

We have approached the process of developing this book with the following guidelines:

- Focusing on the automobile user and pretimed signal operation allows the student to learn about fundamental principles of a signalized intersection, while laying the foundation for future courses that address other users (pedestrians, bicycle riders, public transit operators) and more advanced traffic control schemes such as actuated control, coordinated signal systems, and adaptive control.
- Queuing models are presented as a way of learning about the fundamentals of traffic flow at a signalized intersection. A graphical approach is taken so that students can see how flow profile diagrams, cumulative vehicle diagrams, and queue accumulation polygons are powerful representations of the operation and performance of a signalized intersection.
- Only those equations that students can apply with some degree of understanding are presented. For example, the uniform delay equation is developed and used as a means of representing intersection performance. However, the second and third terms of the Highway Capacity Manual delay equation are not included, as students will have no basis for understanding the foundation of these terms.
- Learning objectives are clearly stated at the beginning of each section so that the student knows what is to come. At the end of each section, the learning objectives are reiterated along with a set of concepts that students should understand once they complete the work in the section.
- Over 70 figures are included in the module. We believe that graphically illustrating basic concepts is an important way for students to learn, particularly for queuing model concepts and the development of the change and clearance timing intervals.
- Over 50 computational problems and two field exercises are provided to give students the chance to test their understanding of the material.

**Acknowledgment**

This module was developed with funding from the U.S. Department of Transportation's University Transportation Centers Program.