Slowing Traffic Flow by Dangerous Street Engineering?

[XLFD]

Strong Towns is a website and a 'movement' self-described as dedicated to making communities financially strong and resilient, it is also a favorite go-to website of several local policy-makers in Ludington .  The ST editors recently revealed that their most 'viral' post this year has been a January 2019 article entitled:  "2 Photos Reveal Why the Key to Slowing Traffic is Street Design, Not Speed Limits"  The article follows in its entirety, followed by an analysis of why I think it was Strong Towns' most-read post by almost a factor of 5.  Hint: it may be because the conclusion is controversial.

2 Photos Reveal Why the Key to Slowing Traffic is Street Design, Not Speed Limits

The cost of auto orientation—designing our towns and cities around the easy, fast movement of cars—is not just measured in dollars and cents. The number of U.S. traffic fatalities in 2017 topped 40,000 people. Nearly 6,000 of those people were on foot—a 25-year high. Each of those people had a unique story. Each of them had a family.

And after each high-profile crash, we all hear the same litany of advice from law enforcement and traffic safety professionals.

       “Be hyper-aware of your surroundings.”
       “Always obey the speed limit.”
       “Speed is a factor in 30 percent of crashes.”
       “Safety is a shared responsibility.”

And yet, we know that people are sometimes going to make mistakes. Even conscientious drivers make mistakes. People walking, going about their business, are going to make mistakes. No one is going to be hyper-vigilant every moment that they’re out in the world. And why should we have to?
We can't regulate our way to safety. We must design our streets to be safe.

Two simple photos reveal what it means to design a street to be safe, versus counting on the speed limit alone to do the job. This meme was created by planner Wes Craiglow of Conway, AR, and shared on social media by the "Transportation Psychologist," our friend, Bryan Jones. We first shared it back in 2015, but it remains timeless, so here it is again:

As Wes points out: "The meme is intended to help viewers consider how different street designs makes you feel as a driver, and ultimately affect how you behave behind the wheel. Generally speaking, as depicted by the lower photo, narrower travel lanes, shorter block lengths, and a tree canopy, all contribute to drivers traveling more slowly. Conversely, wide lanes, long block lengths, and open skies, as seen in the upper photo, communicate to drivers that higher speeds are appropriate.”

Look again at the two photos. Imagine yourself behind the wheel of a car on each street. On which street would you drive faster? On which street would you exercise more caution?

“Forgiving” Design is a Misnomer

The first photo looks like tens of thousands of suburban streets all over America. It’s entirely representative of something the transportation engineering profession calls “forgiving design.” The premise is simple: drivers will make occasional mistakes—veer a bit out of their lane, fail to brake quite hard enough—and if the street is wide, with high visibility in all directions, and free of immediate obstacles such as trees and fences, those mistakes won’t be catastrophic.

The problem: this street feels too forgiving to a driver. Too safe and comfortable. So drivers speed up. The engineers didn’t account for this aspect of human psychology.

This residential street is built like a four-lane highway, and so even though its legal speed limit is 20 miles per hour, it’s no surprise when somebody guns it up to 40 miles per hour or more down a street like this. It feels natural to do so. It feels safe. But it isn’t safe—because on a city street, unlike a freeway, there might be people around. People who will most likely be badly hurt or killed if a speeding driver hits them.

The Paradox of Street Design: If It Feels a Bit Dangerous, It’s Probably Safer

The second photo, on the other hand, represents the most basic, frugal approach to designing a street for slow speeds. It’s not perfect. It lacks sidewalks or bicycle facilities, which some of our readers might take issue with—and yes, many places ought to have those things.

But this “slow street” does something really profound and important. It causes drivers to slow down, whether or not there’s a posted speed limit or law enforcement is present, because of the uncertainty and sense of heightened risk.

The street is narrow. Visibility is limited—look at that front left corner of the intersection, where a red fire hydrant stands next to a white fence. The lack of visibility there is not a safety hazard: paradoxically, it’s probably the single biggest thing that promotes safety at this intersection. Because if you’re driving here, and can’t see whether a vehicle is approaching from the left, what are you going to do?

That’s right. You’re going to slow down.

Why 20 Miles Per Hour?

If we could keep most urban traffic to 20 miles per hour or less, we could eliminate the vast majority of deaths from car crashes in our cities and towns. We wouldn’t eliminate mistakes—people, both inside and outside vehicles, are going to make them—but those mistakes would rarely be deadly.

The place for wide lanes and “forgiving design” is on a high-speed road. City streets, on the other hand, should be places for people. We know how to design streets that will slow down traffic automatically, without the need for heavy-handed enforcement, and regardless of what the speed limit sign says. We just need to do it.

ANALYSIS:  

Traffic slowing was one of the big benefits of making a Ludington Avenue Road Diet (LARD) where five (and sometimes four) lanes would be pared back to three: one going each way and a dedicated turn lane.  Both officials and the public were agreed that traffic would be slowed down, but they primarily disagreed on the possible benefits that the disruption of traffic flow would cause.  Fortunately, the traffic study conducted by MDOT made it clear that any benefits would be outweighed by the problems that would be fostered. 

This article seems to be saying that engineering a road with features that 'psychologically' reduce speeds by drivers is a preferred method.  Some Ludington back streets have such features without needing any special re-engineering:  those features are called potholes.  

The first photo, enlarged above, shows what is considered a traditionally engineered suburban street.  The lanes are wide to allow for street parking or safer bicycle travel on the shoulder.  It also allows fire trucks and garbage trucks enough room to operate and turn around.  Sight lines are far, trees are away from the street, they allow a person to see people and objects well before they are passed.  One would believe that the safe 'natural speed' down this venue would be more than 20 mph.

The second photo, propped up as a great example to show the author's point, has a lot of defects that makes it undesirable and unsafe.  The intersection is rife with fences and vegetation in the 'sight triangles'.  A driver going down this street barely sees a stop sign to the right for that intersecting street, doesn't see it at all on the left, primarily because fencing and bushes are there; it's easy to believe a stopped car could be out of sight until you get to the intersection-- and they won't see you either.  

The lanes could not likely accommodate a fire engine or garbage truck and any other vehicle going in the opposite way without somebody getting off the street.  Further down you see vehicles parked alongside the street on the unpaved shoulder, they would surely slow drivers down when they are worried about hitting them or the vehicle coming from the other way.  You don't see that danger in the first street.

I just don't get this thesis proposed by the Strong Towns author, and how it greatly contradicts some of the basic tenets of complete streets by suggesting streets should include points of danger, in the hope of slowing traffic down, and making accidents with less chance of a fatality.  Can somebody either explain it so that I can understand it better, or agree with me that it's a bizarre notion and explain how you came to that decision?

[Willy]

I'm having a hard time understanding it myself.  "Points of danger" only makes things worse when there are distracted drivers which we have more of these days due to the cell phones. I'm a cautious driver anyway so I would navigate either street above in the same way because any neighborhood street can have pedestrians, cyclist and kids near the street or crossing at any time. Like the weather, there are to many variables to consider unless there are obvious dangers and as long as people are behind the wheel anything can happen. One major problem with the tree lined street are "hidden" driveways or at least they may not be obvious until you get to them. Then again on the open street a sun low in the sky can be a visual distraction, something not to be concerned with on the tree lined street.

The following video involving traffic flow is right up your alley X.