Are traffic engineers asleep at the wheel?
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DENVER — Wes Marshall thinks traffic engineers could learn a thing or two from physicians.
Marshall, a professor of civil engineering at the University of Colorado Denver, opens his new book, “Killed by a Traffic Engineer,” by reflecting on the history of medicine.
“Doctors have been around for, like, 5,000 years,” Marshall told Rocky Mountain PBS. “In the first thousand, you could pretty easily argue that they probably killed more people than they saved. Right now, traffic engineering is only 100 years old.”
Marshall’s book, with its provocative title, argues that traffic engineering — not drivers, pedestrians or “human error” — is primarily responsible for the carnage on our roads. Colorado had a record high in pedestrian fatalities last year. In 2022, the state witnessed 764 traffic deaths, its highest number in history.
There is hope, however. Marshall explains that traffic engineering is still in its infancy, and that it’s not too late to change how we think about roads — or how we design them.
“I'm trying to kind of push us out of the dark ages and realize that we can do better,” he said.
Marshall recently sat down with Rocky Mountain PBS for an interview about his new book. The original interview had to be rescheduled because a driver crashed through this author’s fence just before the sit-down.
This conversation has been edited for length and clarity.
Rocky Mountain PBS: Thinking back to when you first got your engineering license, how early did you realize we could be doing things differently or better?
Wes Marshall: Very early. It's funny. I was at a luncheon yesterday and they were trying to do a get-to-know-you thing, and one of the questions was, “what's your biggest pet peeve?” And it's funny, my pet peeves kind of fueled my career.
Like, I grew up right near Boston. I could walk or bike all over town. That's sort of what I knew. I think none of this stuff bothered me until I finally moved to a place where I couldn't do that. I'm like, “Oh my God, I hate this. I see a corner store here and I literally can't get there in anything but a car.” And I would ask my neighbors about it and none of them cared or knew any differently. In my head, I was like, “they're missing out on so much.”
At work I started trying to figure out why we do what we do, and there was always sort of less behind it than I thought. So at that time, even though I was a professional engineer, I had only taken one transportation engineering course. And I thought I sort of knew everything. I thought all the books were telling me that and I finally went back to grad school and I took all these other courses and was like, oh my God, I knew nothing.
And like that's sort of how the process works. There’s a lot of fortuitousness, lucky stuff in there. But there's really just things that drove me crazy, led to my career, this book.
RMPBS: Speaking of pet peeves, what would you say is the biggest misconception about what leads to traffic crashes?
WM: That's pretty easy: “It's human error.” All our data tells us that almost every crash is a problem of the road user. Like somebody was jaywalking, somebody was speeding, like somebody didn't yield the right of way to somebody else. And that sort of makes you think that it's random accidents. But they're really systematic crashes. We can predict where they're happening and why.
So if you're on Colfax and you're trying to take a left turn onto one of the side streets, you have a green light that's telling you that you can go if you can see a gap in the traffic, right? So as a driver, you're looking for this gap in the traffic. You're trying to figure out when you can take a left turn. At that exact same time, we're telling pedestrians it's their turn to go and they get the white walk sign. So if that driver hits that pedestrian, then we blame it on the driver for not giving the right of way to that pedestrian.
I'm like, “Well, no. We put them in a bad situation.” He had the A pillar there. He can't even see where the pedestrian is. We distracted him with these cars coming at him. Then you have these people pressuring him from behind.
That's a systematic thing that we know that happens in all these urban arterials where there are pedestrians. And all the data tells us it's a human error problem, like “this driver wasn't paying enough attention.” So then we put more money into educating drivers to pay attention instead of designing our way out of it, which we could, but the data doesn't tell us we have a problem.
Other examples are jaywalking. Somebody will jaywalk, they’ll get hit, you blame it on them. But if you zoom out sometimes [and] try to figure out “why did this person jaywalk?” And you’ll see the nearest crosswalk is half a mile away and we have crappy sidewalks between there. So what they did is often a rational thing.
I mean, obviously, there are egregious examples and we're not trying to let human error off the hook, but [blaming human error] doesn't help us design anything better, doesn't help us improve.
RMPBS: I'm curious to hear your thoughts on this, but that kind of perspective strikes me as uniquely American in that things that are systemic problems are often treated as moral failures. I think of addiction, homelessness, even obesity. It’s almost easier to say, “well, that person shouldn't have been doing that” as opposed to asking “what led them to get in this position?” Do you think that’s fair to say?
WM: Well, it’s happening all over the world. I mean, there are some countries that are doing better than others, but you're right, it's easier. It's easier for traffic engineers. It's easier for the police, when they get to crashes, to figure out who's at fault. They're not trying to figure out what's wrong with the road. And that helps the insurance companies, right? They can blame one user, not the other. And again, for the traffic engineers, it lets them off the hook. So it's easier for everybody. And then we can just put money into enforcement education.
Actually, I was biking home yesterday and so out by the [Denver Rescue] Mission and there's a billboard way up in there that says [something like] “Eyes forward, keep your eyes on the road.”
RMPBS: When we talk about human error and the explanations for traffic crashes, drunk driving comes to mind and so does texting while driving. Do you think there's almost an overemphasis on those as the reason behind crashes?
WM: I think it lets the traffic engineers off the hook for — I mean, yes, there are things on the automotive side and technology side that we can do. I sometimes joke that my cell phone has more safety features than my car does.
I remember when Gmail first came to be, they had this one weird feature where if it was, like after midnight, they would ask you three math questions before you sent an email, just to make sure you weren't drunk-emailing somebody.
Our cars don't do that. We have the technology to sort of remove that. We have the technology to make it much harder to text and drive. We don't have to put, you know, 15-inch touch screens in cars. We allow all that stuff, but then we blame the person for using them. We could make it harder. We could kind of nudge them in the right direction.
But at the same time, we make our cars — I mean, what's the speedometer in your car go to? 140? 160?
RMPBS: 140.
WM: Yes, that's a problem, but we also design roads to allow speeds way faster than we want. A lot of these roads downtown, you have four lanes in one direction. If there's nobody around, you could drive 80 miles per hour even though we put a sign up that says you should be driving 30.
We’re sort of enticing people to drive faster and then we blame them when they do and when they crash.
We could also design [roads] to entice slower speeds. But sort of the way the whole system is set up, we want a data-driven approach to safety and the data is telling us we have an education enforcement problem. It's not telling us we have an engineering problem at all.
RMPBS: What are some intersections in Denver proper that are especially egregious in how they're designed?
WM: Well so many of them have that left turn. I don't know if you've heard of the high injury network. So a lot of the cities that are doing Vision Zero, they try to sort of map where the fatalities are and stuff. And for most cities like Denver, you find out that 5% of our streets have like 50% of our fatalities, right?
So it's like Federal Boulevard and Colfax Avenue and Colorado Boulevard — all those sort of big arterials. Those tend to have those systematic left turning issues that I'm talking about.
I biked in on Colfax one day because I was a masochist or something just to kind of see what it was like.
RMPBS: You’ve got a death wish?
WM: Yeah, [laughs] but there's so many jaywalkers and if you kind of take a step back, the intersection where they're supposed to cross is really dangerous. It kind of makes sense that they're trying to do what they're doing.
So, you know, it's easy for [traffic engineers] to just pawn it off on the driver not paying attention to this person who shouldn’t have crossed where they did. I mean, maybe it is uniquely American, but, you know, I think we also export a lot of our traffic stuff to other countries, like the way we do things here. So a lot of people try to follow our lead.
RMPBS: Are there any places in Denver that you think do a really good job in setting up how people can move around?
WM: Places are getting better in Denver. I mean, I think I've noticed that for sure. As I said, I've been here since ‘09 and a lot of stuff that I see in the streets today, I mean, 10 years ago would have been a moonshot.
So right here [pointing behind him] is 15th Street. I think it was around 2013, the city was trying to put in a protected bike lane. This was four lanes of one way traffic at the time. And the city was dragging their heels saying, “We can't take away parking. You can't take away a vehicle driving lane,” that kind of stuff. They eventually put in the bike lane. Over time, they took away two more car lanes. So there's two bus-only lanes and a bike lane. And 10 years ago I was like, “there's no way Denver would ever do that.” But they did. So there's things that are getting better.
And the other thing I appreciate about what they're doing, especially for walking and biking, is thinking more from a network perspective. Historically, we’d put in like one block of a nice bike lane.That doesn't really help very much if you're actually trying to get somewhere. And now, I mean, not just in downtown, but in a lot of the neighborhoods, you see how they're thinking more of a neighborhood greenways, where you can get kind of across a whole section of the city in a low-stress environment.
So I definitely see us heading in the right direction, but there's still a lot of fundamental problems, and that's why we still have so many deaths in this city, this state, this country.
The cover for Marshall's book, "Killed by a Traffic Engineer: Shattering the Delusion that Science Underlies Our Transportation System"
Photo: Island Press
Photo: Island Press
RMPBS: Do you think the pandemic impacted how people perceive mobility and using roads? I think about how many restaurants set up outdoor seating in what used to be parking spots.
WM: I think there's two things that I saw. One is [what you said] — it gave people a chance to see and think about what else the street could be for. Streets are not just for moving cars as quickly to a point as possible, especially in places where there's restaurants or bars or schools or whatever it is. There are social things. Streets themselves are places … and we can use them for so much else.
The other thing, so many more people were out there biking, walking. I think there is some level of empathy that is sort of built up.
If you've only driven, it's hard to understand what it's like to be a bicyclist and maybe to understand why a bicyclist might go through a red light when no one's around, as opposed to waiting for the green light and then fighting with the cars for their space.
I think people started to understand why people are doing what they're doing and having a little more empathy. It's not universal, but there's some of that.
RMPBS: What would you encourage people to do if they wanted to get more of that empathy?
WM: In my class, I've done things where we put a blindfold on students and see what it's like to cross at a crosswalk with no audible tone.
The town I grew up in is where the Perkins School for the Blind is–that’s where Helen Keller went to school. Every single crosswalk in my town had the audible thing. So growing up, I thought that was universal. I thought that everyone did that. I finally go to other places and realize that's not a thing. And you wonder, “Well, how does a blind person know when to cross?” Just that simple [exercise], it changes their mindset as an engineer and designer about what is important and what's not.
You could do the same thing — trying out a wheelchair might be too much — but I mean, push a stroller down some of the sidewalks that we have here that aren’t even two feet wide. You can't even fit a stroller on there. So imagine what it's like being in a wheelchair and having to actually roll in the street because the sidewalk is not good enough.
RMPBS: Do you think there's a changing school of thought around traffic engineering? One that centers moving people as opposed to moving vehicles?
WM: Yeah. I mean, there's definitely people interested in human factors and there's definitely a lot more enlightened engineers that are out there that are trying to do a better job. And even the reception to the book, most of the engineers I talked to were super positive, but there's a few digging in their heels in, like refusing to even read it.
But to me they're kind of proving my point. That's why people kind of see them as a religion more than a science is because they wouldn’t even read what I wrote. So yeah, the shift I hope to see is a shift from more of a theory base to an empirical base.
A lot of the research is telling us that those riders are less safe, but we're still relying on the old theories instead of the new results.
I've got like 75 papers that are published, and I feel like a lot of them just chip away at the tip of the iceberg of the problems that go, “Here's a problem and a way we can do better.”
The book is meant to be more foundational. Like, let's see what the foundation of this discipline is and — maybe not attack that — but show that it's shaky or it's not as strong as even the engineers think.
Despite the title of the book, I don't want to blame them. They're doing what they're taught. They think these 2,000 page books they’re given as manuals are based on science. And I thought the same thing.
I just felt something was wrong, but I didn't really know until I had a chance to dig into it all.
RMPBS: That seems counter to what you’d imagine about engineers — that they're relying on theories as opposed to what the numbers are telling them.
WM: I just couldn’t wrap my head around why I was being told to do these things that just, in the end, seemed worse. And when I finally got a chance to really dig in on all that stuff, there isn't really a reason. It was just more inertia. Like there was one study in the 1930s that said a 24 foot wide road is safer than 18 feet, and we just kind of took the mentality that wider means safer and extrapolated it to like 60, 80, 100 feet.
And it doesn't work. But nobody even knows the specifics of the original study because it's 90 years old, right? So I was trying to unearth that stuff and kind of pull the curtain back, like, hey, here's the guy and here's what he did. And it's not as scientific as any of us thought it was.
RMPBS: And even if it was, it’s 90 years old.
WM: Yeah, right. And maybe that theory is right! But let's see. Let's do it and find out for sure.
RMPBS: I used to live in an apartment on South Broadway and Mississippi Avenue. I would get off the light rail and then I would just have to cross Mississippi to get to my apartment. And when I had the walk sign, there was a green light for the right turn lane. People would take that turn at like 40 miles per hour, and if I wasn’t very vigilant about making sure they saw me…
WM: Right. So we expect kids to cross streets like that. To me, I think that's ridiculous. And then if a kid gets hit, you're just trying to figure out which of them to blame. We can do better. We know we can do better. But sometimes it's easier not to.
Type of story: Q&A
An interview to provide a single perspective, edited for clarity and obvious falsehoods.
An interview to provide a single perspective, edited for clarity and obvious falsehoods.
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References
Marshall, Wes. "Killed by a Traffic Engineer: Shattering the Delusion that Science Underlies our Transportation System" (Book). Published Jun 4, 2024.
Interview: Wes Marshall, professor of civil engineering at the University of Colorado, Denver. Interviewed June 14, 2024.