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Killed by a Traffic Engineer: Shattering the Delusion that Science Underlies Our Transportation System
In the US we are nearing four million road deaths since we began counting them in 1899. The numbers are getting worse in recent years, yet we continue to accept these deaths as part of doing business. There has been no examination of why we engineer roads that are literally killing us.
Fixing the carnage on our roadways requires a change in mindset and a dramatic transformation of transportation. This goes for traffic engineers in particular because they are still the ones in charge of our streets.
In Killed by a Traffic Engineer, civil engineering professor Wes Marshall shines a spotlight on how little science there is behind the way that our streets are engineered, which leaves safety as an afterthought. While traffic engineers are not trying to cause deliberate harm to anyone, he explains, they are guilty of creating a transportation system whose designs remain largely based on plausible, but unproven, conjecture.
Thoroughly researched and compellingly written, Killed by a Traffic Engineer shows how traffic engineering “research” is outdated and unexamined (at its best) and often steered by an industry and culture considering only how to get from point A to B the fastest way possible, to the detriment of safety, quality of life, equality, and planetary health. Marshall examines our need for speed and how traffic engineers disconnected it from safety, the focus on capacity and how it influences design, blaming human error, relying on faulty data, how liability drives reporting, measuring road safety outcomes, and the education (and reeducation) of traffic engineers.
Killed by a Traffic Engineer is ultimately hopeful about what is possible once we shift our thinking and demand streets engineered for the safety of people, both outside and inside of cars. It will make you look at your city and streets—and traffic engineers— in a new light and inspire you to take action.
Fixing the carnage on our roadways requires a change in mindset and a dramatic transformation of transportation. This goes for traffic engineers in particular because they are still the ones in charge of our streets.
In Killed by a Traffic Engineer, civil engineering professor Wes Marshall shines a spotlight on how little science there is behind the way that our streets are engineered, which leaves safety as an afterthought. While traffic engineers are not trying to cause deliberate harm to anyone, he explains, they are guilty of creating a transportation system whose designs remain largely based on plausible, but unproven, conjecture.
Thoroughly researched and compellingly written, Killed by a Traffic Engineer shows how traffic engineering “research” is outdated and unexamined (at its best) and often steered by an industry and culture considering only how to get from point A to B the fastest way possible, to the detriment of safety, quality of life, equality, and planetary health. Marshall examines our need for speed and how traffic engineers disconnected it from safety, the focus on capacity and how it influences design, blaming human error, relying on faulty data, how liability drives reporting, measuring road safety outcomes, and the education (and reeducation) of traffic engineers.
Killed by a Traffic Engineer is ultimately hopeful about what is possible once we shift our thinking and demand streets engineered for the safety of people, both outside and inside of cars. It will make you look at your city and streets—and traffic engineers— in a new light and inspire you to take action.
412 pages, Paperback
First published June 4, 2024
254 people are currently reading
3550 people want to read
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Displaying 1 - 30 of 121 reviews
October 18, 2024
Four stars for the material. Two stars for the writing — and I’m being generous. This thing needs an aggressive editor willing to cut the dated pop culture references and irrelevant footnotes. The author writes about a study that was never completed and, so, has no results to share. Cut it. Case studies are repeated to make the exact same point in several chapters. Words are displayed in bold italics for no reason. This book irritated me more than any I’ve read in recent memory despite finding it agreeable and illuminating. Please, someone edit this into a readable document.
The last couple of sections are dynamite, though.
The last couple of sections are dynamite, though.
April 26, 2024
got this advanced reader copy at the national planning conference! I found it really comprehensible, even with the more technical topics, and it was especially inspiring as I work towards a career in transportation safety myself. even if that doesn’t pan out, I now have the tools and knowledge to be an advocate.
September 17, 2024
Full review to come, but this was excellent and approachable*
*except for random footnotes that added nothing, like this one.
*except for random footnotes that added nothing, like this one.
July 14, 2024
This book is a very accessible and persuasive introduction to the problems created by the past hundred years of traffic "engineering", which has focused exclusively on making it easy and fast for cars to move through places, to the detriment of all other uses of land in the area.
I am already deeply immersed in this topic (and I imagine many readers are as well), and for me the general arguments the author uses are powerful but well-worn and (while extremely important) add little new. The most interesting parts of the book were the places where he quotes and critiques traffic engineering articles and manuals from the 20's - 60's (and today), and shows how they're based on absolutely nothing but guesses (shocking if you haven't heard this before). However, this book is totally nontechnical and avoids getting very deep into the weeds on any particular aspect of street design. Personally, I would really love to see a book that chases down the history of various common design elements (e.g. slip lanes) and picks apart their history, "design standards", and analyzes the real impact they have on the built environment. Short of that, this book has a lot of original source references to chase down for doing such an analysis.
On the unfortunate side, the writing style leaves quite a bit to be desired. The book consists of 88 very short chapters (2-5 pages), each of which consists of a stream of very short paragraphs (often just 1 sentence). This gives a sort of "staccato" rhythm to the writing that at times almost feels like a series of tweets. Also, nearly every page contains some kind of gratuitous reference to a movie or TV show, frequently taking time to quote some joke from the script in its full context. This is really distracting and (for me) falls totally flat. I'm reading this book because the author is an expert in traffic engineering and I want to hear his perspective, not to be reminded of some skit from The Simpsons. I understand traffic violence is a heavy topic, but this is not an effective way to lighten the mood.
I am already deeply immersed in this topic (and I imagine many readers are as well), and for me the general arguments the author uses are powerful but well-worn and (while extremely important) add little new. The most interesting parts of the book were the places where he quotes and critiques traffic engineering articles and manuals from the 20's - 60's (and today), and shows how they're based on absolutely nothing but guesses (shocking if you haven't heard this before). However, this book is totally nontechnical and avoids getting very deep into the weeds on any particular aspect of street design. Personally, I would really love to see a book that chases down the history of various common design elements (e.g. slip lanes) and picks apart their history, "design standards", and analyzes the real impact they have on the built environment. Short of that, this book has a lot of original source references to chase down for doing such an analysis.
On the unfortunate side, the writing style leaves quite a bit to be desired. The book consists of 88 very short chapters (2-5 pages), each of which consists of a stream of very short paragraphs (often just 1 sentence). This gives a sort of "staccato" rhythm to the writing that at times almost feels like a series of tweets. Also, nearly every page contains some kind of gratuitous reference to a movie or TV show, frequently taking time to quote some joke from the script in its full context. This is really distracting and (for me) falls totally flat. I'm reading this book because the author is an expert in traffic engineering and I want to hear his perspective, not to be reminded of some skit from The Simpsons. I understand traffic violence is a heavy topic, but this is not an effective way to lighten the mood.
May 5, 2025
"Insightful yet frustrating" captures my experience with this book about automobile transit in the United States. The author delivers some thought-provoking ideas and innovative solutions, but the reading experience is marred by verbosity, distracting footnotes, and esoteric pop culture references. Additionally, the lack of an index made it difficult to navigate through its contents. Despite these issues, I still found value in certain parts of the book hence giving it 3 out of 5 stars.
The book shines when it introduces innovative ideas to improve safety for pedestrians and cyclists. One concept that stood out was the proposal to install brake lights on the front of vehicles, which could significantly enhance the safety of non-motorists. Another insightful point was the idea of measuring safety per capita rather than per passenger mile traveled—an approach that offers a more comparative measure of road safety for the average commuter.
Recognizing the vulnerability of pedestrians and cyclists, the author suggested special permissions for these road users to enhance their safety. For example, allowing them to advance through a red light early to establish lane presence is a pragmatic solution.
One of the more sobering arguments presented is the notion that autonomous cars are not a catch-all solution to crashes and traffic congestion. The author's observation that the perpetual push for technological limits in cars (speed, efficiency) comes with inherent tradeoffs between safety and efficiency is compelling. This underscores the importance of engineering safer roads and prioritizing pedestrian and cyclist access as we move towards an increasingly autonomous future.
However, several aspects detract from the overall reading experience. The discussions around the actuarial value of life and road design optimization were extensive, but I was surprised by the omission of any analysis on reducing lost Quality-Adjusted Life Years in engineering decisions. Moreover, there are actionable solutions provided for being safer on and around roads, but they are somewhat buried under repetitive content and less effective organization. The chapter titles lack descriptiveness, making it harder for the reader to navigate the book's contents effectively.
In a future edition, a more concise writing style and better-organized chapters would greatly benefit readers. Additionally, reducing redundancy and fixing the distracting footnotes would make the book more engaging.
All in all, while this book presents some thought-provoking arguments and ideas, the execution leaves much to be desired. Though I walked away with new insights, the reading experience was hampered by the book's structure and verbosity. If you're looking for immediate actionable steps to be a safer road user, you might find yourself a bit frustrated. However, the innovative ideas proposed may still warrant a read for those deeply interested in transportation safety and policy.
The book shines when it introduces innovative ideas to improve safety for pedestrians and cyclists. One concept that stood out was the proposal to install brake lights on the front of vehicles, which could significantly enhance the safety of non-motorists. Another insightful point was the idea of measuring safety per capita rather than per passenger mile traveled—an approach that offers a more comparative measure of road safety for the average commuter.
Recognizing the vulnerability of pedestrians and cyclists, the author suggested special permissions for these road users to enhance their safety. For example, allowing them to advance through a red light early to establish lane presence is a pragmatic solution.
One of the more sobering arguments presented is the notion that autonomous cars are not a catch-all solution to crashes and traffic congestion. The author's observation that the perpetual push for technological limits in cars (speed, efficiency) comes with inherent tradeoffs between safety and efficiency is compelling. This underscores the importance of engineering safer roads and prioritizing pedestrian and cyclist access as we move towards an increasingly autonomous future.
However, several aspects detract from the overall reading experience. The discussions around the actuarial value of life and road design optimization were extensive, but I was surprised by the omission of any analysis on reducing lost Quality-Adjusted Life Years in engineering decisions. Moreover, there are actionable solutions provided for being safer on and around roads, but they are somewhat buried under repetitive content and less effective organization. The chapter titles lack descriptiveness, making it harder for the reader to navigate the book's contents effectively.
In a future edition, a more concise writing style and better-organized chapters would greatly benefit readers. Additionally, reducing redundancy and fixing the distracting footnotes would make the book more engaging.
All in all, while this book presents some thought-provoking arguments and ideas, the execution leaves much to be desired. Though I walked away with new insights, the reading experience was hampered by the book's structure and verbosity. If you're looking for immediate actionable steps to be a safer road user, you might find yourself a bit frustrated. However, the innovative ideas proposed may still warrant a read for those deeply interested in transportation safety and policy.
November 9, 2025
not sure if I find all the pop culture references hilarious or cringe, but very eye opening regardless
November 17, 2025
This book was okay but desperately needed better editing. I think the material is likely more engaging in a taught format. I am a huge nerd about road design and still encountered some surprising information - that's good! But ultimately the book's structure (very short chapters particularly) made the polemic call to action at the end less impactful; a stronger sense of narrative is needed to make things flow better.
Having said that, wow, pseudoscience is the word for it.
Having said that, wow, pseudoscience is the word for it.
November 9, 2025
Everything is a lie and the house always wins
July 23, 2024
If you are a transportation & community revitalization nerd like me, this is a great book. As a former & recovering traffic engineer, this hits hard. Over the course of my 30+ year career, with the past 27 at a local government agency, I had gradually come to see the error of my ways. This book articulated what I had been feeling for years quite well. We must prioritize safety over LOS if we want to save our cities. Sadly the old mentality is so ingrained into traffic engineering culture that I wonder if we will be able to turn the tide.
November 6, 2025
I hate cars
This entire review has been hidden because of spoilers.
November 19, 2024
apologies to all my friends I’ve gone on long rants about traffic engineering and walkable cities to in the past week because I’ve been so hooked on this book, it was really good and he gets so many points for referencing both ratatouille and old enough in the span of like three pages. I do think that this book could have been organized better / the points would have been punchier if it were restructured slightly but still loved it and will be thinking about it for a while!
July 4, 2024
Rightfully should be the sort of exposé that does for urban planning what Silent Spring did for chemical manufacturers and The Jungle did for the meat industry.
August 12, 2024
U.S. traffic fatalities are higher than those in other rich countries, and have risen in recent years (especially for pedestrians). In Killed by A Traffic Engineer, engineering professor Wes Marshall explains that this problem is at least partially rooted in American traffic engineering: engineers design streets that accommodate fast vehicle traffic at the expense of safety. Why is this?
Marshall suggests several root causes: 1) First of all, American engineers receive almost no academic training about traffic, and even less about safety. A student can graduate college with a civil engineering degree and pass a licensure exam while having taken no courses related to transportation. Even universities with transportation courses rarely learn anything about road safety.
2) engineers often rely on research that is outdated or irrelevant. For example, 1930s research on industrial worker accidents found that for every accident that caused a major injury, there are 29 that caused minor accidents and 300 that caused no accidents. Traffic engineers noticed this research and assumed that in the traffic context, it was also true that places that have very few small accidents also have very few major accidents. But this point of view is incorrect in the context of auto traffic- a fast-moving highway might have very few minor accidents, but far more severe injuries because if you are hit by a car going 60 miles per hour, you will be more severely injured than if you are hit by a car going 20 miles per hour. Because midcentury traffic engineers did not notice this difference between highways and factories, they thought streets with fast-moving traffic would be safer than they turned out to be. Similarly, the American custom of 12-foot travel lanes is based on research that shows nothing about road safety outcomes, but instead on a 1945 study showing only that trucks “shift slightly more to the right” on narrower roads.
3) traffic engineers try to avoid blame for crashes by blaming human error but overlook the fact that some street design rules are more likely to produce human error than others. For example, Marshall notes that many signalized intersections “give pedestrians the walk signal while we simultaneously allow drivers to turn directly into where we just told pedestrians they could safely walk.” But if both drivers and pedestrians have the right of way at the same time, human error leading to crashes is more likely.
4) traffic engineers treat roads like buildings. When engineers design buildings, they may add larger-than-necessary materials to prevent structures from collapsing. When engineers reason by analogy, they favor bigger roads with higher design speeds. This may be a fine strategy for a limited-access highway, but creates a high risk of death or serious injury on streets that are used by slow-moving road users such as pedestrians and slow-turning vehicles.
Marshall suggests several root causes: 1) First of all, American engineers receive almost no academic training about traffic, and even less about safety. A student can graduate college with a civil engineering degree and pass a licensure exam while having taken no courses related to transportation. Even universities with transportation courses rarely learn anything about road safety.
2) engineers often rely on research that is outdated or irrelevant. For example, 1930s research on industrial worker accidents found that for every accident that caused a major injury, there are 29 that caused minor accidents and 300 that caused no accidents. Traffic engineers noticed this research and assumed that in the traffic context, it was also true that places that have very few small accidents also have very few major accidents. But this point of view is incorrect in the context of auto traffic- a fast-moving highway might have very few minor accidents, but far more severe injuries because if you are hit by a car going 60 miles per hour, you will be more severely injured than if you are hit by a car going 20 miles per hour. Because midcentury traffic engineers did not notice this difference between highways and factories, they thought streets with fast-moving traffic would be safer than they turned out to be. Similarly, the American custom of 12-foot travel lanes is based on research that shows nothing about road safety outcomes, but instead on a 1945 study showing only that trucks “shift slightly more to the right” on narrower roads.
3) traffic engineers try to avoid blame for crashes by blaming human error but overlook the fact that some street design rules are more likely to produce human error than others. For example, Marshall notes that many signalized intersections “give pedestrians the walk signal while we simultaneously allow drivers to turn directly into where we just told pedestrians they could safely walk.” But if both drivers and pedestrians have the right of way at the same time, human error leading to crashes is more likely.
4) traffic engineers treat roads like buildings. When engineers design buildings, they may add larger-than-necessary materials to prevent structures from collapsing. When engineers reason by analogy, they favor bigger roads with higher design speeds. This may be a fine strategy for a limited-access highway, but creates a high risk of death or serious injury on streets that are used by slow-moving road users such as pedestrians and slow-turning vehicles.
January 29, 2025
This book is riveting, and also makes me so angry that we could do just little things to make our roads safer, but people in power are just preoccupied with moving cars fast, which shouldn't be the way a city is designed. I see so many flaws in the streets of Toronto from reading this book.
I wish I was a traffic engineer so that I could fix these problems!
I wish I was a traffic engineer so that I could fix these problems!
August 29, 2024
5 stars for the content -- terrific examination and expose of the "science" of traffic engineering.
2.5 stars for the writing, organization, repetitiveness, and structure.
2.5 stars for the writing, organization, repetitiveness, and structure.
September 15, 2025
...I did not enjoy reading this, and not because all of the anecdotes about pedestrian deaths. Marshall jokes in the dedication (to his family) that "88 chapters on road safety seems like a bit much" and the unfortunate thing is that it's 100% right. This book is 88 disconnected chapters that read like 88 separate essays that someone tried unsuccessfully to corral into related sections. In one of the last sections Marshall tries to use the KonMari Method as a metaphor for what to prioritize when designing roads, but forgets to mention the method right in the middle of that series of chapters/essays. If you dropped me into an essay, I could not tell you what the point of the section was.
I was left with a lot of anecdotes, a bunch of information I feel like I've seen summarized better on Tumblr, and, unfortunately, feeling still unprepared to argue with pro-car activists, which Marshall promises you'll be able to do in his introduction. (At least not beyond the usual, "I don't know how to explain that you should care about other people.")
I was left with a lot of anecdotes, a bunch of information I feel like I've seen summarized better on Tumblr, and, unfortunately, feeling still unprepared to argue with pro-car activists, which Marshall promises you'll be able to do in his introduction. (At least not beyond the usual, "I don't know how to explain that you should care about other people.")
May 15, 2025
Really interesting subject matter and summary of current issues and trends in transportation engineering. However this book desperately needs a better editor. Like this book could have been half the length it is if all the repetition of topics or arguments were removed. I don’t need a whole paragraph every time to explain the history of acronym changes that a governmental agency has gone through each time that agency gets mentioned.
September 29, 2025
2.5/5⭐
Another reviewer said the content was 4/5⭐ but the writing was 2/5⭐ and I couldn't agree more. This was hard to get through and I am glad I'm done but kinda regret sticking with it....
The writing was too informal and just all over the place? Too many random stories and articles and laws and stuff to make a concise argument rather than a watered down one.
I learned a few things so that's good. 😎
Another reviewer said the content was 4/5⭐ but the writing was 2/5⭐ and I couldn't agree more. This was hard to get through and I am glad I'm done but kinda regret sticking with it....
The writing was too informal and just all over the place? Too many random stories and articles and laws and stuff to make a concise argument rather than a watered down one.
I learned a few things so that's good. 😎
June 10, 2024
As a traffic engineer, I find this book a good read. Written in somewhat witty language, it gives a good overview of the last 100 years of transportation and traffic research in the US, and it's heavily referenced. A bold critical view on transportation system that asks questions why we do things the certain way and how we got to this point where almost 40k people die each year on US roads (in comparison, 56k US troops were killed during Vietnam War that lasted almost 20 years).
June 10, 2025
Education. Enforcement. Engineering. When someone dies on the road, what do we blame? Spoiler: it’s usually not the road engineering!
Wes Marshall does an excellent and engaging job describing the flaws of traffic engineers, the common mistakes they make, and their refusal to use new information to make better choices. Some of the things I’ve learned from this book have been staggering. For example, it’s commonly believed that higher speeds mean more safety — so highways are safer than local roads. But actually, in reality, there are fewer fender benders but more severe and fatal crashes instead — high speeds in areas with pedestrians and bicyclists is a recipe for disaster. I was already aware of some of the engineering issues that induce speeding, but what I didn’t know is that it is all, and continues to be, by design — for more capacity, more vehicle miles travelled, and for “less”
Congestion. But our methods aren’t working, they aren’t making the streets safer, and people are still being killed every day by drivers. What can we do to make the roads, and our lives, safer? This book was great, and highly recommend it.
Wes Marshall does an excellent and engaging job describing the flaws of traffic engineers, the common mistakes they make, and their refusal to use new information to make better choices. Some of the things I’ve learned from this book have been staggering. For example, it’s commonly believed that higher speeds mean more safety — so highways are safer than local roads. But actually, in reality, there are fewer fender benders but more severe and fatal crashes instead — high speeds in areas with pedestrians and bicyclists is a recipe for disaster. I was already aware of some of the engineering issues that induce speeding, but what I didn’t know is that it is all, and continues to be, by design — for more capacity, more vehicle miles travelled, and for “less”
Congestion. But our methods aren’t working, they aren’t making the streets safer, and people are still being killed every day by drivers. What can we do to make the roads, and our lives, safer? This book was great, and highly recommend it.
September 23, 2025
A great book that touches on the very foundations of traffic engineering. The author clearly has learned a lot over his own career, and it shines a light on many genuinely new perspectives and criticisms of contemporary engineering, especially from a safety perspective (a lot of urbanist criticism comes from a perspective that the current environment is unpleasant or inefficient, not a laser-focus on safety). I was very satisfied with the book and very much enjoyed the reading experience. My only criticism is that it was a little too entry-level for my own taste, and did not go into as much technical detail as I would have preferred. The book consists of 88 "chapters", at most maybe 4-5 pages each, which shine a light on things like how we collect data, how we act on it, design, etc. This makes the book very easy to read, however does make it less efficient as a reference. Especially when the book prefers more simple prose to get its point across to a wide audience; you won't get lost in technical jargon here. I'd recommend the book to anyone who wants to get a deeper understanding of why and how traffic engineering is so flawed as a discipline.
November 6, 2025
I really liked this book, especially as it explains a lot about traffic engineering for the layperson. It's also depressing as heck, showing how much of what modern traffic engineers use in their standards and guidelines are based on ... nothing. No real studies, no science. One heavily cited source of information about bikes on the road is traced back to a 1970s paper about one engineer's personal biking anecdote--what?! I also rather enjoyed the last few parts talking about some ways to fix things.
However, I really wish the author had organized and written the book slightly differently, as wow, he makes a lot of pop cultural references, to a frankly annoying degree. I listened to this in audiobook, but I gather from the other reviews that it had annoying footnotes and typographical emphases in print. I kinda wanted a book I could buy for all my city councilors, but I may just pull out specific chapters instead.
I learned a lot, though, so I appreciate that. All in all, a good supplement to anyone interested in good livable cities with useful roads that won't encourage death.
However, I really wish the author had organized and written the book slightly differently, as wow, he makes a lot of pop cultural references, to a frankly annoying degree. I listened to this in audiobook, but I gather from the other reviews that it had annoying footnotes and typographical emphases in print. I kinda wanted a book I could buy for all my city councilors, but I may just pull out specific chapters instead.
I learned a lot, though, so I appreciate that. All in all, a good supplement to anyone interested in good livable cities with useful roads that won't encourage death.
November 10, 2024
Acho que nunca grifei/destaquei tanto um livro.
Wes Marshall vai atrás dos estudos e argumentos que formaram a base dos manuais de engenharia de tráfego responsáveis por definir como as ruas são utilizadas. E surpresa, surpresa, não há base científica para a grande maioria das regras e a segurança é um fator raramente considerado no planejamento urbano.
Claro que Marshall foca nos Estados Unidos, mas a lógica foi exportada pelas fabricantes de automóveis e aplicada pelo mundo afora. Essa lógica é responsável pela morte de mais de 1 milhão de pessoas todos os anos.
Embora seja um tema árido, Marshal escreve como se estivesse mandando um whatsapp para um amigo e acrescenta exemplos e referências culturais do cinema e das artes, o que retira o peso e torna a leitura até divertida. Ainda sim é um livro para quem se interessa pelo tema.
Wes Marshall vai atrás dos estudos e argumentos que formaram a base dos manuais de engenharia de tráfego responsáveis por definir como as ruas são utilizadas. E surpresa, surpresa, não há base científica para a grande maioria das regras e a segurança é um fator raramente considerado no planejamento urbano.
Claro que Marshall foca nos Estados Unidos, mas a lógica foi exportada pelas fabricantes de automóveis e aplicada pelo mundo afora. Essa lógica é responsável pela morte de mais de 1 milhão de pessoas todos os anos.
Embora seja um tema árido, Marshal escreve como se estivesse mandando um whatsapp para um amigo e acrescenta exemplos e referências culturais do cinema e das artes, o que retira o peso e torna a leitura até divertida. Ainda sim é um livro para quem se interessa pelo tema.
March 22, 2025
Everyone who works in the transportation field should read this book. It is so eye opening to see that the standards we use for everything are based on so little, and it is abundantly clear we are not doing enough to prioritize safety in this country.
Do I feel attacked as a traffic engineer myself? Maybe a little, but I mostly feel energized to apply what I've learned from this book to make my community safer.
This read was also very engaging, Wes Marshall found a way to make it compelling when it could have been a snooze fest. Maybe it was all the footnotes. It was a bit repetitive at times, but overall I appreciated how approachable this was.
Do I feel attacked as a traffic engineer myself? Maybe a little, but I mostly feel energized to apply what I've learned from this book to make my community safer.
This read was also very engaging, Wes Marshall found a way to make it compelling when it could have been a snooze fest. Maybe it was all the footnotes. It was a bit repetitive at times, but overall I appreciated how approachable this was.
March 20, 2025
This book is written by a traffic engineer and is made up of dozens of short essays, each on a very specific sub-topic of traffic engineering. The writing isn't particularly compelling, which is not surprising for a traffic engineer. A number of essays seem redundant or bland. But taken altogether, it does paint a really enticing picture of traffic design as unsafe by design and offers a few but not enough action items to make things much better.
October 16, 2025
3.5 stars. Has some interesting concepts, but eventually seemed a little repetitive by the end. Demonstrates a lot of good data and stories to go along with how poorly our streets are designed in regards to safety pedestrian and traffic safety. Its no wonder the United States has the second-highest road fatality rate among OECD countries, behind only Colombia.
January 10, 2025
It's pretty terrifying to realize that the whole traffic infrastructure in this country is based on a bunch of envelope math and no real data. I hope the people who need to read this book get a copy handed to them!
November 5, 2025
Traffic crashes have taken four million American lives since the invention of the automobile — including about 870,000 pedestrians. Four million is more than six times greater than the number of American military personnel (646,596) who have died in battle since the Revolutionary War.
Traffic deaths per 100,000 residents is 14.2 in the USA. By contrast, the rate is 4.7 in Canada, 4.5 in Australia, 3.3 in Germany, 2.7 in Japan, 2.4 in the UK, and 1.5 in Norway. In addition, pedestrian deaths in the U.S. have jumped by 78% since 2009. The United States has the worst pedestrian safety record among peer countries.
In sum, the status quo entails an a high toll in serious injuries and deaths. Consequently, traffic engineers should find it unacceptable to follow the status quo.
Conventional wisdom blames driver error for the vast majority of traffic deaths. It's true that some drivers behave badly, however, environmental factors such as speed limit and the design of vehicles and roads often determine whether predictably imperfect driving has fatal consequences.
The thesis of his book is that traffic engineers have designed and built a transportation system "that incites bad behavior and invites crashes." Wes Marshall wants engineers to fix the system that encourages human error.
A civil engineer and professor at the University of Colorado, Marshall contends that traffic engineers have failed miserably when it comes to creating safe roads.
Driver error "makes it easy for traffic engineers to pass the buck." Blaming the bad driver takes attention away from design flaws that lead to preventable deaths and injuries.
It also takes pressure off of manufacturers to design safer vehicles and of public officials to require safer vehicles, to lower speed limits, and to conduct adequate enforcement. Marshall says it well: "The inclination to blame human error is pervasive — across nearly all disciplines — because it simplifies things."
That distraction by passing-the-buck argument was made in another book I reviewed: "THERE ARE NO ACCIDENTS: The Deadly Rise of Injury and Disaster—Who Profits and Who Pays the Price" by Jesse Singer (2022, Simon & Schuster).
Engineers who attribute 90% or more of crashes to human error should explain why Americans make so many more mistakes than their counterparts in Canada, Australia and Europe.
It's a truism that human behavior is influenced by the environment. Consequently, it's appropriate to use a systems approach to understand crash patterns.
Certain highway design is conducive to sleepiness; falling asleep behind the wheel accounts for as many as 13% of fatalities. When examining crashes, analysts should ask why the individuals behaved as they did. What environmental factors were present?
Another example is when roads are wide and straight, drivers are comfortable traveling at higher speeds than when roads are narrow and winding. Collisions at high speed are more likely to be fatal. In short, driver behavior changes with the type of roadway.
Driver error falls into predictable patterns. If engineers simply blame driver error, they relieve themselves of looking for design deficiencies and of devising designs to reduce predictable mistakes.
"Safety is our #1 priority" is a slogan popular among traffic engineers. They point to the road fatality rate, which is the number of deaths divided by miles driven (rather than deaths per 100,000 people). By that metric, the US is doing well. The main reason for improvement is increases in miles driven.
"Safety first is a lie," Marshall asserts. "Safety has never been the top priority." Design capacity actually gets more attention.
If pedestrian safety were priority one, then crosswalks would not be half a mile apart, speeds would not be so high that vehicles have difficulty stopping for someone in the crosswalk, and pedestrians would not be directed to cross while traffic is making right or left turns.
Competing priorities that often take precedence are enhancing mobility and efficiency, minimizing congestion, and curbing costs. For example, a design could improve vehicle speed and traffic movement instead of allowing pedestrians sufficient time at lighted crosswalks.
One way engineers avoid taking specific measures to reduce crashes is to say that "safety is a shared responsibility." In other words, others are to blame. Engineers also cite "the standards" to avoid including safety enhancements. The truth is they are usually referring to guidelines, not to inflexible rules.
William Haddon, the leading pioneer in traffic safety, wrote something in 1965 that Marshall insists is still true: Traffic engineers base "programs on unsupported presumptions... often with dogmatic public assurance as to their efficacy."
Engineers follow what's in their manuals, but many of those prescriptions are not based in science. Marshall calls it "pseudoscience."
One of the three Es of traffic safety is Education (along with Engineering and Enforcement.
If only drivers could be taught to follow the law!
Marshall's goal is to better educate the traffic engineers. One thing he wants them to learn is to not blame lack of education and enforcement for their own shortcomings.
Engineering can be used to make safer vehicles. Since speeding is a major factor in traffic deaths, speed governors could be installed in vehicles, but the US chooses not to do so. As a result, most vehicles can be driven well over 100 mph, with 120 to 140 being common top speeds. Is there any good reason a driver not on a racetrack would ever need to go that fast?
Early attempts to require speed governors were defeated by the auto industry. Also rejected is geofencing technology that could limit speeds within cities. (At least speed governors have been enacted for electric scooters.)
Opponents of using such technology say speeds are a matter of a driver's personal responsibility. Yet more than half of crash injuries happen to people who weren't driving.
It's a myth that, when it comes to fatalities, speed uniformity is more important than how fast a vehicle is traveling. Some engineers still believe outdated research claiming speed doesn't kill as long as most vehicles are within 10 mph of each other.
Traffic engineers generally favor setting speed limits based on whatever speed 85% of drivers are below. Crowdsourcing speed limits is based upon the premise that most drivers operate at reasonable and prudent speeds.
When speed limits are raised using the 85th percentile rule, traffic tends to speed up even more. That's because a "mountain" of research finds that drivers treat speed limits as their low-end baseline.
In addition, the National Transportation Safety Board in 2017 found scant evidence that the 85th percentile speed equates to fewer crashes on all types of roads.
What matters more than speed limits, however, to influence driver speed are road design and the amount of traffic. When designing a road, engineers first select the "design speed," and then tailor the road to accommodate that speed.
To improve safety, engineers should select a target speed and then design the road to discourage exceeding that limit. In other words, design to instruct drivers how fast to go instead of letting drivers determine the right speed via the 85th percentile.
If we aren't willing to slow vehicles down, we could make them lighter and therefore less deadly in a collision. Just the opposite has been happening. Electric cars are 20% heavier than the same model that uses gasoline.
Heavier vehicles are safer for those inside them, but are less safe for persons in other vehicles, pedestrians and bicyclists. The problem is that "vehicle engineering focuses on those buying the vehicle rather than upon the greater good."
SUVs and pick-ups could be designed to better protect pedestrians, but no American regulation requires it. The auto industry has a sordid history of fighting mandatory measures such as safety belts and air bags. Yet airbags save 2,800 lives a year.
Here are some more useful facts:
○ Road design influences driver behavior more than a speed limit sign.
○ Lower speeds lead to signicantly fewer traffic injuries and deaths.
○ Classes in highway design rarely mention the safety consequences of design decisions.
○ Urban areas have a lower crash rate than more rural areas.
○ More traffic congestion leads to fewer serious injuries and deaths. Ergo, reducing congestion may increase crash severity.
○ Randomized control experiments are rare in traffic safety. That's a reason funds are spent on unproven measures in the name of safety.
○ Cities commonly have 50% of their serious injuries and deaths on only 5% of streets. Nearly 100% of these injury hotspots have three or more lanes and 70% have five or more lanes.
○ It was long believed that wider lanes were safer. Research suggests the opposite because wider lanes invite higher speeds than narrower ones.
○ Another common assumption is that one-way streets are safer. Research finds that drivers go faster on one-way streets and are more inclined to run redlights.
○ In the mid-twentieth century, building urban freeways through city neighborhoods was justified as safer than slow, crowded city streets. It turns out that freeways dividing city neighborhoods failed to reduce fatalities or congestion.
○ Mass transit is about 20 times safer than driving. A 1% rise in mass transit use equals a near 3% drop in traffic deaths. In short, expanding mass transit is a safety intervention.
○ "The greatest barriers to road safety are the places we've built that force people to drive everywhere, all the time, even for the simplest errand."
The traffic death toll is not inevitable. The World Health Organization says that "road traffic injuries are a major but neglected public health challenge." The public health approach would put the spotlight on reducing injuries and deaths rather than fender benders and congestion. We should treat traffic deaths more like train or airplane deaths.
Marshall recommends that engineering schools start teaching classes specifically about road safety, few of which currently exist. Traffic engineers should know the differences in crash frequency and severity between alternative designs.
He also calls for a feedback loop so traffic engineers can know the crash frequency and severity of their design decisions. The feedback would be useful for those who can shed their fixed mindset and defensiveness and learn from mistakes.
When dealing with transporation, municipalities usually require a traffic impact analysis. They should also require a road safety impact analysis. We need to understand how the transportation system shapes human behavior. Then design better systems rather than blaming human error. When designing roads, prioritize pedestrians and bicyclists first instead of last.
Moreover, "we need to reexamine everything we do and admit to ourselves that, when it comes to road safety, our system to train engineers is lacking, oversimplified, and often focused on the wrong things."
The status quo exacts a steep cost in human lives. As Wes Marshall cogently argues, it doesn't have to be that way. -30-
Traffic deaths per 100,000 residents is 14.2 in the USA. By contrast, the rate is 4.7 in Canada, 4.5 in Australia, 3.3 in Germany, 2.7 in Japan, 2.4 in the UK, and 1.5 in Norway. In addition, pedestrian deaths in the U.S. have jumped by 78% since 2009. The United States has the worst pedestrian safety record among peer countries.
In sum, the status quo entails an a high toll in serious injuries and deaths. Consequently, traffic engineers should find it unacceptable to follow the status quo.
Conventional wisdom blames driver error for the vast majority of traffic deaths. It's true that some drivers behave badly, however, environmental factors such as speed limit and the design of vehicles and roads often determine whether predictably imperfect driving has fatal consequences.
The thesis of his book is that traffic engineers have designed and built a transportation system "that incites bad behavior and invites crashes." Wes Marshall wants engineers to fix the system that encourages human error.
A civil engineer and professor at the University of Colorado, Marshall contends that traffic engineers have failed miserably when it comes to creating safe roads.
Driver error "makes it easy for traffic engineers to pass the buck." Blaming the bad driver takes attention away from design flaws that lead to preventable deaths and injuries.
It also takes pressure off of manufacturers to design safer vehicles and of public officials to require safer vehicles, to lower speed limits, and to conduct adequate enforcement. Marshall says it well: "The inclination to blame human error is pervasive — across nearly all disciplines — because it simplifies things."
That distraction by passing-the-buck argument was made in another book I reviewed: "THERE ARE NO ACCIDENTS: The Deadly Rise of Injury and Disaster—Who Profits and Who Pays the Price" by Jesse Singer (2022, Simon & Schuster).
Engineers who attribute 90% or more of crashes to human error should explain why Americans make so many more mistakes than their counterparts in Canada, Australia and Europe.
It's a truism that human behavior is influenced by the environment. Consequently, it's appropriate to use a systems approach to understand crash patterns.
Certain highway design is conducive to sleepiness; falling asleep behind the wheel accounts for as many as 13% of fatalities. When examining crashes, analysts should ask why the individuals behaved as they did. What environmental factors were present?
Another example is when roads are wide and straight, drivers are comfortable traveling at higher speeds than when roads are narrow and winding. Collisions at high speed are more likely to be fatal. In short, driver behavior changes with the type of roadway.
Driver error falls into predictable patterns. If engineers simply blame driver error, they relieve themselves of looking for design deficiencies and of devising designs to reduce predictable mistakes.
"Safety is our #1 priority" is a slogan popular among traffic engineers. They point to the road fatality rate, which is the number of deaths divided by miles driven (rather than deaths per 100,000 people). By that metric, the US is doing well. The main reason for improvement is increases in miles driven.
"Safety first is a lie," Marshall asserts. "Safety has never been the top priority." Design capacity actually gets more attention.
If pedestrian safety were priority one, then crosswalks would not be half a mile apart, speeds would not be so high that vehicles have difficulty stopping for someone in the crosswalk, and pedestrians would not be directed to cross while traffic is making right or left turns.
Competing priorities that often take precedence are enhancing mobility and efficiency, minimizing congestion, and curbing costs. For example, a design could improve vehicle speed and traffic movement instead of allowing pedestrians sufficient time at lighted crosswalks.
One way engineers avoid taking specific measures to reduce crashes is to say that "safety is a shared responsibility." In other words, others are to blame. Engineers also cite "the standards" to avoid including safety enhancements. The truth is they are usually referring to guidelines, not to inflexible rules.
William Haddon, the leading pioneer in traffic safety, wrote something in 1965 that Marshall insists is still true: Traffic engineers base "programs on unsupported presumptions... often with dogmatic public assurance as to their efficacy."
Engineers follow what's in their manuals, but many of those prescriptions are not based in science. Marshall calls it "pseudoscience."
One of the three Es of traffic safety is Education (along with Engineering and Enforcement.
If only drivers could be taught to follow the law!
Marshall's goal is to better educate the traffic engineers. One thing he wants them to learn is to not blame lack of education and enforcement for their own shortcomings.
Engineering can be used to make safer vehicles. Since speeding is a major factor in traffic deaths, speed governors could be installed in vehicles, but the US chooses not to do so. As a result, most vehicles can be driven well over 100 mph, with 120 to 140 being common top speeds. Is there any good reason a driver not on a racetrack would ever need to go that fast?
Early attempts to require speed governors were defeated by the auto industry. Also rejected is geofencing technology that could limit speeds within cities. (At least speed governors have been enacted for electric scooters.)
Opponents of using such technology say speeds are a matter of a driver's personal responsibility. Yet more than half of crash injuries happen to people who weren't driving.
It's a myth that, when it comes to fatalities, speed uniformity is more important than how fast a vehicle is traveling. Some engineers still believe outdated research claiming speed doesn't kill as long as most vehicles are within 10 mph of each other.
Traffic engineers generally favor setting speed limits based on whatever speed 85% of drivers are below. Crowdsourcing speed limits is based upon the premise that most drivers operate at reasonable and prudent speeds.
When speed limits are raised using the 85th percentile rule, traffic tends to speed up even more. That's because a "mountain" of research finds that drivers treat speed limits as their low-end baseline.
In addition, the National Transportation Safety Board in 2017 found scant evidence that the 85th percentile speed equates to fewer crashes on all types of roads.
What matters more than speed limits, however, to influence driver speed are road design and the amount of traffic. When designing a road, engineers first select the "design speed," and then tailor the road to accommodate that speed.
To improve safety, engineers should select a target speed and then design the road to discourage exceeding that limit. In other words, design to instruct drivers how fast to go instead of letting drivers determine the right speed via the 85th percentile.
If we aren't willing to slow vehicles down, we could make them lighter and therefore less deadly in a collision. Just the opposite has been happening. Electric cars are 20% heavier than the same model that uses gasoline.
Heavier vehicles are safer for those inside them, but are less safe for persons in other vehicles, pedestrians and bicyclists. The problem is that "vehicle engineering focuses on those buying the vehicle rather than upon the greater good."
SUVs and pick-ups could be designed to better protect pedestrians, but no American regulation requires it. The auto industry has a sordid history of fighting mandatory measures such as safety belts and air bags. Yet airbags save 2,800 lives a year.
Here are some more useful facts:
○ Road design influences driver behavior more than a speed limit sign.
○ Lower speeds lead to signicantly fewer traffic injuries and deaths.
○ Classes in highway design rarely mention the safety consequences of design decisions.
○ Urban areas have a lower crash rate than more rural areas.
○ More traffic congestion leads to fewer serious injuries and deaths. Ergo, reducing congestion may increase crash severity.
○ Randomized control experiments are rare in traffic safety. That's a reason funds are spent on unproven measures in the name of safety.
○ Cities commonly have 50% of their serious injuries and deaths on only 5% of streets. Nearly 100% of these injury hotspots have three or more lanes and 70% have five or more lanes.
○ It was long believed that wider lanes were safer. Research suggests the opposite because wider lanes invite higher speeds than narrower ones.
○ Another common assumption is that one-way streets are safer. Research finds that drivers go faster on one-way streets and are more inclined to run redlights.
○ In the mid-twentieth century, building urban freeways through city neighborhoods was justified as safer than slow, crowded city streets. It turns out that freeways dividing city neighborhoods failed to reduce fatalities or congestion.
○ Mass transit is about 20 times safer than driving. A 1% rise in mass transit use equals a near 3% drop in traffic deaths. In short, expanding mass transit is a safety intervention.
○ "The greatest barriers to road safety are the places we've built that force people to drive everywhere, all the time, even for the simplest errand."
The traffic death toll is not inevitable. The World Health Organization says that "road traffic injuries are a major but neglected public health challenge." The public health approach would put the spotlight on reducing injuries and deaths rather than fender benders and congestion. We should treat traffic deaths more like train or airplane deaths.
Marshall recommends that engineering schools start teaching classes specifically about road safety, few of which currently exist. Traffic engineers should know the differences in crash frequency and severity between alternative designs.
He also calls for a feedback loop so traffic engineers can know the crash frequency and severity of their design decisions. The feedback would be useful for those who can shed their fixed mindset and defensiveness and learn from mistakes.
When dealing with transporation, municipalities usually require a traffic impact analysis. They should also require a road safety impact analysis. We need to understand how the transportation system shapes human behavior. Then design better systems rather than blaming human error. When designing roads, prioritize pedestrians and bicyclists first instead of last.
Moreover, "we need to reexamine everything we do and admit to ourselves that, when it comes to road safety, our system to train engineers is lacking, oversimplified, and often focused on the wrong things."
The status quo exacts a steep cost in human lives. As Wes Marshall cogently argues, it doesn't have to be that way. -30-
July 13, 2024
A well-written, easily digestible book on the traffic engineering profession. The damage done to US communities by building roads only for the safety of cars and efficient car travel has city leaders, urban planners clamoring—with a sense of urgency— to repair the harm of level of service and traffic flow over safe streets and access for people biking and walking.
Long-time advocates will find new ways to explain the harm and be equipped with stronger language when asking transportation planners to do differently. This book will make you angry and hopeful at the same time.
Long-time advocates will find new ways to explain the harm and be equipped with stronger language when asking transportation planners to do differently. This book will make you angry and hopeful at the same time.
August 24, 2024
Enjoyable, although at times heavily depressing, read. Informative and well-researched filled with a mixture of academic and pop-culture references. Author has a great casual, but thorough style of writing. Accessible and illuminating read.
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