Built for Speed

Roman Mars:
This is 99% Invisible. I’m Roman Mars.

[MUSIC]

Roman Mars:
I want you to conjure an image in your mind of the white stripes-

[MUSIC FROM ‘THE WHITE STRIPES’]

Roman Mars:
Not those white stripes, but the white stripes that divide the lanes of traffic going in the same direction on a major highway. How long are those stripes? You can spread your arms out to estimate if you want to. Over the course of many years, a psychology researcher named Dennis Shaffer at Ohio State asked students from many different parts of the country this question.

Dennis Shaffer:
The most common response was two feet.

Roman Mars:
So, if you’re like most people you estimated that those white stripes are two feet long. Maybe a little more. But if you did, you’d be very, very wrong. This is Tom Vanderbilt.

Tom Vanderbilt:
My name is Tom Vanderbilt. I’m a writer in New York and the author of “Traffic: Why We Drive the Way We Do (And What It Says About Us).”

Roman Mars:
Every three pages of Tom’s terrific book “Traffic,” I can probably turn into a 99% Invisible episode. But back to the highway.

Tom Vanderbilt:
Well, early on in my research, I was talking to a highway engineer-

Roman Mars:
And he said if your car is ever broken down on the side of the road…

[SOUND OF CAR PASSING ON HIGHWAY]

Tom Vanderbilt:
If you’ve ever been forced to get out of your vehicle on a highway-

Roman Mars:
Just take a moment to notice what a strange landscape it is.

Tom Vanderbilt:
If you happen to be standing near a road sign, these road signs are huge. I mean, they’re not meant to be experienced as humans on foot. They’re meant to be experienced at 75 miles an hour-

Roman Mars:
With that clear view typeface.

Tom Vanderbilt:
Perfectly visible, retroreflective.

Roman Mars:
And then, there are the white stripes.

Tom Vanderbilt:
If you actually got out of your car and were able to walk on a closed highway and walk from one end of those stripes to the other, you’d find that… I mean, years ago in the United States, the highway standard was 15 feet long which is longer than a car itself.

Roman Mars:
Current federal highway administration guidelines suggest a length of 10 feet with 30 feet between the dashes.

Tom Vanderbilt:
That’s something that is shocking to people.

Roman Mars:
And remember, most people in the Shafer study said that those stripes were two feet long.

Tom Vanderbilt:
That’s such a vast gulf between…It’s not like “they’re actually five feet, we thought they were two” margin of error kind of thing.

Roman Mars:
And it goes back to this fundamental point that when you’re in a car at high speeds, you’re experiencing only a sense of the landscape rather than the actual landscape.

Tom Vanderbilt:
This kind of sense of landscape has been presented to you, to essentially make you feel comfortable.

Roman Mars:
And to make a highway work at what are really evolutionarily ridiculous speeds for a human to travel.

Tom Vanderbilt:
You have this big flat wide open kind of stretch of road that even if you have a 65 mile an hour sign, the message of the road is telling you something entirely different. I think that’s really where a lot of our behavior comes from. Sometimes you have sort of willful speeding, willful kind of lawbreaking. But a lot of it is just people paying attention to the visual messaging on the road, not to their speedometer.

Roman Mars:
Long dividing lines and clear vistas give the illusion that you’re going at a reasonable speed. As soon as something encroaches into view, you get a sense of how fast you’re going. That’s one reason why those temporary concrete walls that crews put up right next to the road during construction are so unnerving. The air and perception of white stripe length is attributed to the fact that when we drive on the highway, we tend to look so far ahead that we usually only experience the dashes and gaps when they are very far away, at an angle where they look shorter. But there’s no consensus as to why people all over the country were so consistently wrong with the two feet estimate.

Tom Vanderbilt:
It’s become my favorite…one of my favorite cocktail party facts.

Roman Mars:
Mine, too.

Tom Vanderbilt:
Stump the driver with this white stripes information.

Roman Mars:
I don’t want to leave with the impression that the wide dividing lines are uniform, though.

Tom Vanderbilt:
You won’t find 10-foot highway lines on a, say, a boulevard in New York City.

Roman Mars:
And you probably won’t find 10 or 15-foot stripes on bridges or highway on-ramps.

Tom Vanderbilt:
Or let’s hope you don’t because that’s kind of an entirely inappropriate design language for that space.

Roman Mars:
Limited access highways are designed for a very precise purpose.

Tom Vanderbilt:
The highway is meant for uninterrupted fast-flowing traffic — get people from point A to Point B as quickly as possible with no interruptions. I mean, that sort of environment does not work in cities or suburbs.

Roman Mars:
The problem is when that approach is grafted into places where it doesn’t belong.

Tom Vanderbilt:
People are actually kind of paying the price for this right now in some suburban environments where you find these kinds of arterial highways that were built almost to a highway engineering standard with, again, these long sightlines, wide roads encouraging people to go fast. And then we went and built all kinds of development along those arterial highways which was never really supposed to be there.

Roman Mars:
But with so many people driving on these roads, they became absolutely irresistible to commerce.

Tom Vanderbilt:
This is kind of the new American “Main Street,” right? Where you have your Costco’s and your fast food and all sorts of in and out parking lots, driveways, drive thru’s; yet, people also going very fast. And a guy named Eric Dumbaugh does a lot of research suggesting that these are really some of the most dangerous places to currently drive in America. Not crowded urban cities, which is what a lot of people would think.

Roman Mars:
The whole approach is called the “forgiving road.”

Tom Vanderbilt:
The idea was to first try to minimize the potential that a crash could happen through, again, through lack of obstacles, generous sightlines, all these sorts of things. But then if a crash did happen, to kind of mitigate the effects of what would happen to not punish the driver for the mistake that he will inevitably make, this was– I’m quoting some of the language from the time. So, you see that nowadays in things like in California, you’ll have your guardrails that are sort of wire guardrails that if a car strikes that guardrail, it tends to catch on the guardrail rather than being bounced back out into traffic which causes another series of collisions.

Roman Mars:
So, this forgiving road is a positive thing in terms of good safety engineering.

Tom Vanderbilt:
But they were so seduced by it that the call was made to bring it into that even the surface street network. So, things like street trees began to be deemed hazards by engineers. Just outright hazards. And that makes sense on a high-speed country road. But if you’re talking about a residential street where you’re not supposed to be going more than 25 anyway, is the presence of a street tree on the side of the road where it’s providing shade and comfort to pedestrians. Is that the same sort of hazard? Is it even a hazard at all?

Roman Mars:
The conclusion many planners came to was ‘yes,’ trees are a hazard.

Tom Vanderbilt:
You find pre-war suburbs… You have a street, a set of trees, and then the sidewalk. Post-war, this sort of shift began to happen where the tree’s were moved on the other side of the sidewalk.

Roman Mars:
Suddenly pedestrians were put into the position of being the buffer between drivers and those menacing trees.

Tom Vanderbilt:
There was sort of a pernicious thing that happened here is that, as you move those trees away, the visual sensation of the road became wider. And if there’s one kind of iron law of traffic engineering that gets into this visual perception thing as well, the wider a road is or is perceived to be-

Roman Mars:
The faster driver speed tends to increase.

Tom Vanderbilt:
And, of course, the final… if you look at sort of 1990s-era suburbia, they just kind of eliminated the sidewalk and the trees altogether. So, that was sort of the final solution. Just eliminate any kind of hazard.

Roman Mars:
And Tom Vanderbilt says you can almost date a subdivision’s development based on that shift.

Tom Vanderbilt:
This points to one of the problems about road engineering is that humans tend to consume the extra engineering measures that have been built in for their safety. Much in the same way, I like to draw the analogy with some of the research that’s been done on food packaging by Brian Wansink at Cornell University. You’re doing experiments where if you give people, just a random group of people, large buckets of popcorn filled to the top with popcorn and give them a smaller amount of popcorn in a smaller package that they’ll just eat more of the larger package whether they’re… it has nothing to do with their level of hunger, it’s just the size of the package influences their behavior. And I think a lot of our road environments are sort of like that. They’re over-engineered for the safety and then we tend to consume a lot of the extras getting us back to this kind of homeostatic edge that we’re always kind of playing with, I think.

Roman Mars:
99% Invisible is Sam Greenspan and me, Roman Mars. It’s a project of 91.7 local public radio KALW in San Francisco and the American Institute of Architects in San Francisco.

You can find the show and “like” the show on Facebook. That’s where a lot of the discussion and interaction happens so join us over on Facebook. We’re getting pretty close to 10,000 likes which I would really enjoy. I tweet @romanmars and we have links to all the stuff we’ve been talking about in this episode at 99percentinvisible.org.