This Video Reveals the Not-so-Secret History of Deadly Street Design


Our streets are a slow-rolling emergency. Motor vehicles in the United States claim about 40,000 lives every year—that’s about 7,000 more than are killed by firearms in the US each year—and injure many times more people than that. And a big part of the blame belongs to an idea that has been conventional wisdom in the traffic engineering profession for several decades now.

A Disastrous Idea: “Forgiving” Design

Forgiving design is the principle that even city streets should be built like highways, with wide lanes, gentle curves, lots of visibility and broad “clear zones” so that if you veer off the road, there won’t be a tree or light post or brick wall right there for you to hit. This sounds like a great idea until you account for this problem of human psychology: “forgiving” streets simply induce drivers to speed up.

We’ve been beating this drum at Strong Towns for a decade, along with many of our peer organizations that advocate for safe, walkable streets. And we see the message catching on in a wider way than ever before.Case in point: a new video from streaming news and entertainment site Cheddar starts out with a meme that we helped popularize!

The video, which credits Strong Towns for inspiration, and which as of this writing has already been viewed nearly 700,000 times, adds some nice historical context to the debate. In it, the folks at Cheddar explain how a surge of concern for automobile safety in the 1960s (and a couple crucial pieces of testimony before Congress at the time) led to the widespread institutionalization of “forgiving” design standards—and even rules that prohibited nice, quiet, inherently slow streets like the one you see on the bottom of the photo pair at right.

We can’t help but detect some serious Strong Towns influence toward the end of Cheddar’s video too, when the narrator points out:

[The profiled] transportation engineers collapsed an important distinction. There's a difference between roads and streets. Roads are simply about connecting to places. They're designed to facilitate speedy, efficient movement. Streets are about building place and economic value.

We couldn’t have said it better. Here’s the video:

Transcript

(From YouTube’s Closed Captioning)

In 2015, an urban planner in Arkansas created this meme. Which street is safer? They're both residential streets with a 20 mile per hour speed limit. But while this street was designed to be more forgiving to drivers, this is actually the safer street.

So, why have we been building so many streets like this one over the past 50 years? In 2017, traffic deaths hit a 25-year-high of 40,000 fatalities. Six thousand of those killed were pedestrians. Cities across the country are trying to reduce traffic fatalities with safety campaigns. One of the keys to the whole problem might be a flawed mid century design philosophy.

There was a big transportation safety movement in the 1960s. This is when we saw the development of airbags and crash tests. In 1965, Ralph Nader published a book about the designed-in dangers of cars and roads. He accused car companies of resisting safety improvements in order to cut costs. The book was a best seller. It led to Senate hearings, which then led to the creation of the Department of Transportation, which eventually led to the creation of the National Highway Safety Administration.

There were two key testimonies during congressional safety hearings in 1966 that paved the way for a flawed approach to street design. One was Ralph Nader. Where our safety laws had previously been about enforcing safe driving behaviors like following the speed limit, Nader's testimony led to a shift in thinking. He said, "Even if people have accidents, even if they make mistakes, even if they are looking out the window or they are drunk, we should have a second line of defense for these people. The sequence of events that leads to an accident injury can be broken by engineering measures, even before there is a complete understanding of the causal chain."

The other key testimony came from a senior engineer at General Motors. Ken Stonex helped GM Design a so-called crash proof highway test site called "The Proving Ground". What happens when a front tire blows at 90 miles an hour? Let's find out. Perfect control, basic built-in stability. The proving ground had wide clearances, 100 feet on either side of the roadway, as a safety measure for drivers. Crash data from the proving ground showed that most cars that ran off the road came to a stop within 30 feet. The committee at the hearing seized on this data. One of the main sources of traffic fatalities at the time was single vehicles running off the road and colliding with a fixed object like a tree or light post. Stonex testified that we should operate 90 percent or more of our surface streets just as we do our freeways, and that we should convert streets to proving ground road and roadside conditions.

By 1967, the 30-foot clear zone was adopted into the official standard for road design. The Nader and stonex testimonies reflect a bigger idea called "Forgiving Design". The thinking goes,"No driver is infallible, mistakes will be made. So, let's design our roads and streets with that in mind to be as forgiving as possible when a driver does make inevitable errors, they've got plenty of room to regain control."

The critical flaw in this thinking: this design doesn't account for how drivers would adjust their behavior in a forgiving environment. A forgiving environment has wide clear shoulders, wide straight travel ways, high visibility. But when you drive on a street like this, something happens. Your brain perceives this as a safe environment. So, even if the posted speed limit is 20 miles an hour, that subconscious feeling of safety means your speed tends to creep up and up.

If you remember driver's ed, you remember: speed kills. When you're hit by a car going 20 miles an hour, nine out of 10 times you'll survive. But as speed increases, the numbers get pretty grim. So, urbanists and safety advocates are trying to get us to think about how we can slow drivers down when we're not on highways. Streets like this one with its tree canopy and narrow lanes were actually outlawed when The Forgiving Design Movement took hold. This street looks and feels more hazardous to a driver. You don't have great visibility, you have to weave around parked cars in a narrow lane, sensing the inherent risk in the environment, you tend to take things a little slower, no matter what the posted speed limit says.

Does this mean that Stonex's proving ground data was totally wrong? Not at all. But he and other transportation engineers collapsed an important distinction. There's a difference between roads and streets. Roads are simply about connecting to places. They're designed to facilitate speedy, efficient movement. Streets are about building place and economic value.

So, over the last decade, urbanists have begun to call into question the old forgiving design philosophy. Forgiving design is forgiving to drivers at high speeds on highways and arterial roads, but it's not the safest design for urban streets where you've also got to think about pedestrians and cyclists. It's a case of the design not matching up with the use. But now that Urbanists have pointed out the problem, we're starting to see a return to design elements that subconsciously encourage drivers to take it slow. Thanks so much for watching. Hit the comments to let us know if you have any examples of excellent or a terrible road design where you live, and hit the bell icon to be notified next time we post a video. See you next time.