Review of Traffic Operations at Intersections: Learning and Applying the Models and Methods of the Highway Capacity Manual Using Simplified Scenarios and Computational Engines by Michael Kyte and Rod Troutbeck

The book Traffic Operations at Intersections: Learning and Applying the Models and Methods of the Highway Capacity Manual Using Simplified Scenarios and Computational Engines by Michael Kyte and Rod Troutbeck provides readers an opportunity to better understand the methodologies of the Highway Capacity Manual (HCM). With its evolution from the 147-page 1950 HCM to the 1,069-page, three hard copy volumes and various supplements, 6th edition HCM (published in 2016), the HCM has continually evolved into something that can be challenging for the most experienced traffic engineer to understand, let alone a new traffic engineering employee or graduate student. With each version of the manual, the processes and procedures have become more and more complex, making it harder and harder to understand the processes and easier and easier to simply rely on software packages to perform the analysis. As such, there was a need to provide a textbook that would bring the current version of the HCM to life and allow all who read and study its pages an opportunity to better understand the methodologies behind the analysis of intersections. As stated in the Introduction to the book: “Our major objective in writing this book was to transform the ‘black box’ of the HCM intersection models, and their software implementations, into a ‘clear box’ that allows the engineer to better understand how these models actually work. When you have completed reading and studying this book, you will better understand the fundamentals of the HCM intersection models and you will be able to apply these models to the kinds of complex intersections that you find in the field with skill, confidence, and insight.”

The HCM includes methods to analyze the operations of intersections including all-way stop-controlled (AWSC) intersections, two-way stop-controlled (TWSC) intersections, roundabouts, and signalized intersections. As such, chapters include “Capacity of All-Way Stop-Controlled Intersections,” “Capacity of Two-Way Stop-Controlled Intersections,” and “Capacity of Signalized Intersections.” The format of each chapter is very straightforward and well laid out with sections outlining the contents of the chapter, what one might observe in the field with respect to each topic, formulation of the various models, a variety of scenarios that one could encounter for the three different scenarios, and calculations necessary to perform the analysis. With 95 tables, 138 figures, and 116 equations, the authors provide the reader with a very thorough analysis and understanding of the topics covered in the HCM. Each chapter also includes a glossary of terms, a summary of variables and other notations used in the chapter, and references to guide the reader to other resources available on the topic.

With more than 75 years of combined experience, the authors, Michael Kyte and Rod Troutbeck, have extensive knowledge and experience in teaching the concepts of intersection analysis. Using this experience, they developed a pedagogical approach that combines simplified scenarios and computational engines to allow the reader to delve into the models and methods that make up the intersection chapters of the HCM. By focusing on one element at a time, the simplified scenarios model allows the reader to develop a basic understanding of the operation of an intersection that can be built upon as more complex scenarios arise. Eleven simplified scenarios are developed in the book: two for AWSC intersections, two for TWSC intersections, and seven for signalized intersections. The authors take these simplified scenarios and implement the computational procedures for each into what they call a computational engine that provides the reader with the opportunity to either apply what they have learned using the computational engines available on the book’s website, or develop their own computational engines using the background information provided in the book. Either will allow the reader to apply the concepts learned; however, building your own computational engine allows you to more fully understand and apply the concepts.

The book’s website also includes problem sets for each chapter (120 problems total) that can be utilized in university curriculum, training courses, or simply to help readers better understand the application of the material. Although the book is primarily meant to be a companion to the HCM, it could easily be used as a supplemental or primary text in a senior design or graduate-level traffic engineering, traffic flow theory, traffic operations, or traffic control systems course. For my own purposes, I am using the book as a supplemental text for my graduate-level traffic engineering course. That may change as I continue to dig into the book and identify ways that I could use this as my primary source. The content has been reviewed by students as noted in the Acknowledgments section: “Our students provided valuable insights on this material over many years, struggling with early versions of the book and wondering why we made the material so difficult! We did listen to your feedback (and complaints) and hope that this final version reflects your many good ideas.” The content matter as well as the supplemental materials provided with the book make this a desirable source as a textbook for students. Of course, the relatively low price is also a plus!

Is the book perfect and complete? No. The authors acknowledge this themselves, noting that they chose to omit some scenarios (e.g., roundabouts and the inclusions of nonmotorized vehicles) from the book to focus on the basic concepts that can be built upon later. Hopefully the authors (or others) will take this book as an example and build upon it in the future. One thing that could also be considered in the future would be to make it available as an eBook linked directly to the online resources.

Overall, Traffic Operations at Intersections: Learning and Applying the Models and Methods of the Highway Capacity Manual Using Simplified Scenarios and Computational Engines by Michael Kyte and Rod Troutbeck is a great resource for understanding the intersection models in the HCM that I foresee being used for many years to come. Those who would particularly benefit from this book include upper-level undergraduate students, graduate students, and practicing professionals.