A few weeks ago, I was driving on S. Ashland Avenue near Swap-O-Rama on Chicago’s southwest side. Ashland’s four lanes feel like a highway there. Back in 2017, the Chicago Tribune identified Ashland—particularly the stretch between 43rd and 87th—as the deadliest street for pedestrians. It’s not uncommon to see people trying to cross without a crosswalk or stoplight, despite the dangers. (You can even see a person’s perilous journey in Google Street View.) There’s no crosswalk for almost half a mile between Pershing and 42nd Street. You must traverse several parking lot entrances to get to the closest crosswalk (on either side of the street). Once you add in the temperature, limited shade, and public transit unreliability, a desperate dash across Ashland begins to make sense.
These factors could be considered when designing streets like Ashland (both here in Chicago and across the country). But often, they aren’t. And when they aren’t, it makes you wonder if pedestrians are simply an inconvenient afterthought. As pedestrian and cyclist deaths surge nationally, and the cost of crashes mounts, traffic engineers (the people who design streets) are receiving increased scrutiny.
If you’re unfamiliar with how streets are designed and built, Wes Marshall’s new book, Killed by a Traffic Engineer: Shattering the Delusion That Science Underlies Our Transportation System, may radicalize you. Marshall, a professional engineer who teaches at the University of Colorado Denver, is calling for “an enlightenment” in traffic engineering. His book answers the question: What if Martin Luther’s Ninety-five Theses were about road design and brimming with pop culture references? Across almost 350 pages, he dispels the notion that safety has ever been at the center of the street design regime and argues that many of the sacrosanct theories of traffic engineering are rooted in “pseudoscience.”
For decades, he writes, “traffic engineers designed and built a system that incites bad behaviors and invites crashes. . . . Most deaths and injuries are the predictable, systemic outcomes that traffic engineers inadvertently caused.” Marshall sees it as his mission to try to undo the damage that’s been done. He’s concerned that even recent transportation approaches, like Vision Zero, that explicitly mention safety and casualty reduction are still just “business as usual under a new slogan.” Marshall’s work covers a lot of ground, making it essential reading whether you’re focused on one street in your neighborhood or your pastime is arguing with traffic engineers at public meetings.
This conversation has been edited for length and clarity.
Joe Engleman: What do you want people to understand about how roadways are designed?
Wes Marshall: When [traffic engineers] want to design something, they study it for a year, put together construction drawings, and the final design goes out on the street.
To me, design is an iterative process. That’s how it is in so many other disciplines. It should be in our field, too. Before we put in a protected bike lane, why don’t we test it with cones to understand how it works, where it works well, and where it doesn’t? Instead of studying the “final and best design” on our computer screen, study it out there.
Traffic engineering is based a bit too much in theory. We [engineers] came up with these theories that make perfect sense [on paper], but transportation is counterintuitive. It’s useful for the public to know that you can argue with an engineer. Engineers will shut down conversations using technical jargon by saying, “We have to use our standards.” But these aren’t standards, for the most part; they’re guidelines. Engineers will say they ran traffic models, give you their alternatives, and even argue that it will make things safer, but this isn’t based on safety. Engineers have a lot more leeway—what’s called engineering judgment—than they lead you to believe.
I recently took an Illinois Department of Transportation survey which asked you to identify the three most pressing safety issues in your area. You could choose from 15 preselected responses. Ten answers related to how drivers are educated (e.g. “seat belt usage” or “lack of understanding laws”) or how traffic laws are enforced (e.g. “need more roadside safety checks”). Only a few responses related to how streets are designed. Why is there so much focus on education and enforcement rather than engineering?
Engineering is the most expensive—and it means doing something, right? The research shows that education doesn’t work, but telling drivers to be safer or pedestrians not to jaywalk is easier and makes you feel like you’re doing something. Enforcement pawns the problem off on the police, which doesn’t work in the long-term, and there are issues with racial profiling. We all want to take a more data-driven approach to safety, but our crash data tells us it’s either one road user or the other: someone was at fault, speeding or jaywalking.
In many cases, the onus comes back to the traffic engineer and transportation planners. When engineers build an overly wide road and somebody speeds on it, yes, we want to hold them accountable. But we can do better. When somebody jaywalks and the nearest crosswalk is half a mile away, you start to realize that they did a very rational thing. We pawn it off as being a human error problem—which is useful for the insurance companies and the police—but it takes away the feedback loop for traffic engineers. We can’t get better when we treat crashes that way.
A significant number of people have been killed or injured in recent months on Pulaski Road, a street that’s under the State of Illinois’s design jurisdiction. Would you talk a bit about the role of federalism in road design?
When I was a consultant in New England, I worked in places with a town center out of a Norman Rockwell painting, where a highway, managed by a state department of transportation (DOT), runs through it. The DOT is not going to allow a bike lane there, even though it’s the sort of village that should have one. There’ve been cases of towns and cities taking back control of that short stretch of road. But that’s sort of a cop-out because there’s no reason the state DOT can’t design a better road.
Vision Zero [a strategy to eliminate traffic deaths and severe injuries] cities are creating high injury network maps which tend to show that 50 percent of fatalities are happening on 5 percent of your streets. Most of these streets are run by state DOTs. Those are the most traffic-engineered streets in our cities. And there’s something fundamentally wrong when, the more traffic engineering we do, the more likely we are to kill people.
“If we think the whole system is unsafe, we can prioritize within that, as opposed to waiting for bad things to happen.”
You point out that cities taking safety seriously can still end up being reactive. Would you talk a bit about what a proactive or systemic approach could look like?
Marie Kondo suggests you take all the clothes that you own and put them in one place so you can see the scale of the problem instead of repeating the same mistakes. Instead of playing Whac-A-Mole, we should think about one issue holistically and comprehensively.
In the book, I start off with kids. Well, where do kids go? Kids go to schools, kids go to parks. Where do kids live? We can design our streets and intersections to be safer for kids and where they’re going. We can do different things than we do now: we know kids don’t cross the street at the typical three-and-a-half feet per second, so we could give kids more time to cross. We could set the stop bar further back because kids are shorter and can’t be seen by people in bigger cars.
We could do these things proactively instead of waiting for a kid to get hurt or killed. That’s what I want to shift us to. If we think the whole system is unsafe, we can prioritize within that as opposed to waiting for bad things to happen.
“Traffic engineering is around 100 years old, and we’re killing more people than we save.”
A recent report found that Chicago loses an estimated $6.1 billion annually due to congestion. You raise a provocative point about the value of time saved in the book. Would you talk about that?
I understand why the federal government, insurance companies, and traffic engineers put a dollar value on a life or the time wasted in traffic, but I have a hard time with it. Maybe it’s a moral thing. Those numbers aren’t apples to apples. If you get to work two minutes faster, you don’t make more money.
If you think that way then you can say, “If we can save everybody one minute a day, we’re OK killing somebody,” because the value of that one minute multiplied by everybody is worth more money than what we say a life is worth. It doesn’t make any sense, and you wouldn’t want to do it, but if you think about it holistically, we’re building our transportation system around those numbers.
Anybody with a logical moral compass will say, “What? Are you sure we should prioritize this over that?” It’s shocking when you see it for the first time. But for engineers, adding numbers to everything removes us from moral questions and keeps us above the fray.
What are the most important things you want people to understand about the history of traffic engineering and where it’s at today?
Doctors and medicine have been around for 5,000 years, and you could argue doctors probably killed more people than they saved for the first thousand years. Traffic engineering is around 100 years old, and we’re killing more people than we save.
It’s not on purpose. We’re trying—we’re doing what we’ve been taught. We’re doing the best we can in a lot of cases, but we need to get back to being an empirical science so we can do better.
For further reading on traffic safety in Chicago…
???? Chicago Metropolitan Agency for Planning’s recent report Speed Management: Addressing our regional traffic safety crisis
???? May 1, 2024, Chicago City Council’s Committee on Pedestrian and Traffic Safety hearing on lowering the citywide speed limit.
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