‘Where the Sidewalk Begins’: an excerpt from Wes Marshall’s Killed By A Traffic Engineer

We’re pleased to present an excerpt from Wes Marshall’s book, “Killed by a Traffic Engineer”, and we’re equally thrilled to be hosting Marshall as a keynote speaker at this year’s upcoming National Bike Summit. Learn more about the Summit and register on our Summit page!

From Killed by a Traffic Engineer by Wes Marshall. Copyright © 2024 Wesley Marshall.
Reproduced by permission of Island Press, Washington, D.C.

When we do have leftovers, the basic idea is to separate pedestrians and bicyclists from the drivers and their vehicles. We can do so either temporally or spatially.

Temporal separation is as simple as a walk phase on a traffic signal. The idea is for pedestrians to use part of the street at one time and drivers to use it at a different time. This approach rarely ensures safety because our de facto design allows drivers to, for example, turn right on red or take a permissive left at the same time we tell pedestrians it’s their turn to cross.

Spatial separation used to mean building something like an expensive pedestrian overpass over a terrible street. Whenever I see one or hear somebody propose one, I take it as an admission of failure. In other words, we can’t possibly make this street safe enough for humans to cross on foot. Instead, we need to spend millions building a bridge that is extremely annoying for people to use. It’s like lipstick on a pug.²

These days, spatial separation might mean protected bike facilities. In the words of our old pal Paul Hoffman on the first page of his 1939 book, protected bike facilities offer “a degree of safety that the white lines alone could never guarantee.”

Paul wasn’t talking about protected bike lanes, though. He was trying to bolster his argument for turning our streets into highways. Yet the same thinking applies here.

All protected bike lanes aren’t created equal, either. A flimsy plastic post isn’t going to protect anyone like a concrete barrier or steel bollard could. But the reason a plastic post isn’t good enough is because our streets aren’t good enough. It’s reasonably feasible to design a street that calms drivers down to a speed where we don’t need bike lanes or even sidewalks to safely walk and bike. It’s just not reasonably likely.

It wouldn’t be hard to argue that the humble sidewalk is the most fundamental of all transportation infrastructure. Yet when you ask most city traffic engineers about their sidewalks, they put their hands up as if they are trying to get away with an obvious foul in an NBA game.

My student Peyton Gibson interviewed traffic engineers from 16 different cities about their roadway asset management processes. Every city tracked its roadways and did so on a regular basis with hired consultants who drive the entire network using a vehicle mounted with high-tech sensors that collect high-quality, geo-located data.

We then asked the same questions about sidewalks. The most common response was a frustrated sigh and a warning that “it’s complicated.”

Five cities had no data whatsoever on their sidewalks. Ten cities knew where sidewalks existed but had no information on basics such as width. Only one city was collecting data in a similar ballpark to their roadway data.

Got a pothole? One city fixes 90 percent of them within 24 hours. Most cities do so within 48 hours. The longest was less than five days.

But if your sidewalk is falling apart, good luck getting the city to help. In fact, most cities will turn around and tell you to fix it yourself.

For whatever reason, “the fundamental value of sidewalks and the corresponding need to provide a safe walking path” are “often forgotten or deferred” and “viewed more as a luxury.” This 1978 Traffic Quarterly paper goes on to say, “While it is apparent that sidewalks serve an essential function, it is equally apparent that in many areas sidewalks are missing, discontinuous, or unsuitable for pedestrian use.”

That wasn’t news. Even AAA, in 1958, said that “adequate sidewalks are another responsibility of engineers.”

You could argue that AAA promoting sidewalks was more about getting the pedestrians off the street and out of the way. Whatever their motivation, it’s better than what the Urban Land Institute said at the time. Their 1954 Community Builders Handbook worries that when it comes to the safety of kids, sidewalks may do more harm than good: “It has been hinted that sidewalks actually tend to encourage playing in the street rather than in off-street areas such as rear yards or a playground.”

When asked for evidence, the director of the Traffic Operations Division of the National Safety Council admits that we just don’t know: “Unfortunately there is no good accident information available which would demonstrate the relationship between child safety in areas with sidewalks and without sidewalks.”

Why don’t we know? Well, we don’t collect the sidewalk or exposure data needed to answer such basic questions.³ That was true when said in 1957, and it’s true today.

The bigger issue is that this sort of thinking misses the point. Even if we had the data and found that not having sidewalks or bike facilities helped confine kids to their backyards and led to better road safety, is that really what we are looking for? Of course not.

In his book Bicycle Diaries, David Byrne of the Talking Heads says, “Being in a car may feel safer, but when everyone drives it actually makes a less safe city.” David Byrne is talking about crime—along the lines of Jane Jacobs’s eyes-on-the-street concept—but the same is true about road safety. Put everyone in a car, and your city isn’t going to be safe. But build the sort of infrastructure that gets people out walking and biking, and your city is going to be safer.

This result goes against the grain of conventional traffic engineering thinking. On average, you are about 20 times more likely to die when walking a mile than driving a mile. Bike a mile? That’s maybe 10 times more dangerous than a mile in a car. But guess what happens in cities with lots of people walking or biking? They end up as our safest cities, far safer than conventional cities where everyone is conventionally driving.

Safety isn’t the only benefit.

My cholesterol level was at 222 when my doctor said it was time for medication. When I asked what I could do exercise-wise instead, the answer was getting my heart rate up with cardio for at least 20 straight minutes every day. I was active before, but not quite like that. I figured that biking to work—about a half hour each way—would do the trick. Six months later, my cholesterol level was at 149.

It’s hard to say what exercise does for mental health, but the research suggests good things.

How much money does biking to work save me compared to driving and paying to park? It adds up over time.

It saves me time as well. The last time I checked, the average commuter in the Denver region spends about 40 hours each year stuck in rush-hour traffic. I spend zero.⁴

If I drove to work, I’d have to spend time looking for a parking space, paying to park, and then walking from one of the campus parking garages to my office. Instead, I park my bike in my office.

And whenever I couldn’t figure out how the puzzle pieces of this book fit together, they came together on those bike rides. I’ve also heard that walking and biking are good for the planet. But guess what? Most people aren’t going to risk their lives on dangerous streets out of the goodness of their environmental heart. It doesn’t matter if walking and biking save money, time, our health, and the planet if you feel like you are going to die the whole time.

So my second Kondo category is simple: focus on making your streets and intersections safe for walking and biking. We’ve already done so in and around where kids go; now do so for the rest of your city.

But how?

I could go through all the tools in the traffic engineering toolboxes. Some are simple, like the all-pedestrian phase Barnes Dance. Others get more complicated, like some of the protected bike inter- section designs. My favorite interventions tend to focus on slowing drivers down while also prioritizing those walking and biking. Australia’s wombat crossing, for instance, places a sometimes-colorful zebra crossing on top of a wide, raised speed hump. Even when there are no pedestrians around, the wombat humps slow drivers down to 20 or 25 mph.

Suffice it to say there are a lot of good—and bad—designs out there. But before focusing on those, let’s change our fundamental design approach.

Many safe street groups use an upside-down triangle diagram with a pedestrian icon at the top and a car icon at the bottom. In between, you see bikes, scooters, buses, and trains closer to the top with trucks and freight closer to the bottom. The idea is that safe street efforts, including Vision Zero, should prioritize the needs of the pedestrian first and those of cars last.

This doesn’t stop traffic engineers from doing what we always do: thoroughly designing for cars, leaving those walking and biking with the leftovers.

But what if we followed that mantra of the upside-down prioritization triangle and actually designed for pedestrians first? Instead of starting at the centerline of the street—as traffic engineers are taught—we design from the outside in. Start at the edges and figure out how much space the pedestrians need. Then do the same for bicyclists. And then transit. Whatever’s left over goes to drivers.

With this reprioritization, the de facto intersection designs could change as well. Making a right turn on red would be prohibited unless a traffic engineer signs off on a variance. The same goes for protected pedestrian signals; allowing permissive left turns becomes the exception, not the norm.

Make the intersections safe to cross and guess what? Pedestrians opt to use them instead of opting for jaywalking and giving us so-called human error to blame.

In 2017, the American Society of Civil Engineers asked me to give a presentation about the future of transportation. Going into that event, it was clear that the other two guys in my session were going to talk all about our amazing, electric, autonomous, high-tech future.

I rained on their parade. Why? Well, the future they laid out isn’t as simple as they were saying it was. Even if we get technology to work. Even if it works in all kinds of weather. Even if it does so without having to reboot at inopportune times. Even if we get all that right, we still need everyone on board. We don’t get all the benefits we’ve been promised—including many of the safety ones—without every car on the road being autonomous.

But guess what? People love driving. There’s a reason why The Fast and the Furious movie franchise made billions of dollars. While driving is not exactly a constitutional right, trying to force people to use autonomous vehicles—or even electric vehicles—might end up mirroring the US gun debate.

The real future of transportation isn’t that different than it was 20 or 200 years ago. That’s why some of our simplest streets and cities have worked for hundreds of years and continue to do so. The real future of transportation will always come back to the fundamentals of walking and biking.

So let’s start there and build in. Make your city safe for walking and rolling—and for kids to do so—and it will be safer for everyone.⁵ Let drivers and autonomous vehicles adapt to that future, not the other way around.

Until then, I have a hard time getting excited about this amazing, electric, autonomous, high-tech transportation future of ours while we live in a world where we can’t even get the sidewalks right. If a kid can’t safely sell lemonade on the sidewalk in front of where they live, we’re doing something wrong.

Let’s stop working harder on getting people to Mars and instead work harder on helping them cross the street. I think E.T. would agree.

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1. As mentioned earlier in the book, a sharrow is the common name for a shared-lane bike marking that we paint in the vehicle lane to remind drivers that bicyclists have the right to exist in the street. ↩︎
2. I meant to write “pig,” but I liked my typo and kept it. ↩︎
3. In the same report, the American Society of Planning Officials (precursor to the American Planning Association) said the research doesn’t matter because “sidewalks, like babies and cars, are here to stay.” ↩︎
4. The only exception was the Denver Broncos’ Superbowl parade. As a New England Patriots fan, I wanted no part of that nonsense and biking around it was a nightmare. ↩︎
5. Jeff Speck’s Walkable City books are a great resource for making that happen. It is interesting to note (at least to me) that my stepfather, Richard Bartley, was Jeff’s high school track coach. Once we figured out this connection, Jeff spoke so highly of him and told me that my stepfather instilled a confidence in him that he never knew he had. My stepfather recently passed away as I was finishing up this book. ↩︎

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