I picked up a fresh first printing of this book from the Island Press booth at the American Planning Association’s National Planning Conference held in April 2024, in Minneapolis. Killed by a Traffic Engineer: Shattering the Delusion that Science Underlies Our Transportation System, the full title, sports a striking black and red cover design showing an damaged STOP sign. While 387 pages long, with twelve parts, and 88 chapters, the book was a fairly quick read.
Don’t let the shocking title discourage you from reading this book. Wes Marshall, PhD, PE, a professor of civil engineering at the University of Colorado (CU), Denver wrote it. He directs the CU Denver Human-Centered Transportation Program and the Transportation Research Center at CU Denver. He obtained his BS Civil Engineering from the University of Virginia and his MS and PhD from the University of Connecticut.
In the first part of his book Marshall reminds the reader of the high number of roadway deaths and injuries in the United States. Marshall reminds us that, “more people have died on US roads than in all US wars and conflicts combined, including the American Revolution.” On a per capita basis, the United States suffers one of the highest fatality rates of all countries tracked by the Organization for Economic Co-Operation and Development (OECD).
Marshall’s writes with a conversational, somewhat emotional tone that may turn some readers off. While his tone (and the book’s title) makes it clear that he is very passionate about the topic, it may hinder the book’s ability to reduce injuries and deaths on our roadways and to change how traffic engineers think about their jobs.
Marshall dives into the history of traffic engineering standards since the dawn of the automobile. He notes a 1900 publication by William Eno (while there were only 8,000 registered cars in the United States) that proposed that drivers stay to the right and wave their arms to indicate their intention to turn or stop. Throughout the book, Marshall quotes articles and papers published in the 122 years during which the number of registered cars increased from 8,000 in 1900 to 283 million in 2022.
Marshall explains the history of the standards and design procedures used by traffic and transportation engineers today. He demonstrates that Level of Service, Clear Zones, Lane Widths, Slip Lanes, Left Turn Lanes, Median Size, Intersection Controls, Design Speed, Sight Distances, and other standards all emerge from a desire to increase motor vehicle volumes and speeds in our transportation system, rather than enhance safety outcomes. He also provides examples of journal articles that claim, without evidence, that these standards improve safety.
I had many “Wow, I did not know that,” “Wow, that’s surprising,” and general “AH-HA!” moments when reading this book. I had an AH-HA! moment when I read Marshall’s discussion of safety factors in structural and traffic engineering. Structural engineers follow standards and design procedures to deliver cost efficient buildings that don’t fall down. They use enough steel or concrete to achieve a safety factor and to accomodate building code required loads. Traffic engineers follow design procedures and seek to meet – or exceed – recommended minimum standards for lane widths, design speeds, clear zones, and other parameters. They think, a 13 foot wide lane must be better than a 12 foot wide lane, because the standard specifies a minimum. Bigger is better right? This leads to roads that encourage high speeds and more injuries and deaths.
He describes how law enforcement, local governments, state governments, federal agencies, and academia track fatalities, injuries, crashes, and other transportation system events and how the current approach fails to provide useful feedback to engineers and policy makers who wish to change standards and design methods to achieve better safety outcomes. Standards can’t be updated if we don’t have the data to demonstrate the improvement.
He provides suggestions for improving safety outcomes throughout the book, but I would have preferred for them to be concisely summarized in one place. Overall I recommend planners, engineers, and policy makers read this book. It is available from Island Press: https://islandpress.org/books/killed-traffic-engineer#desc