CategoryBooks

Why are children getting hurt in the street because of “looming”?

Adults are better than children at detecting the speed of a car that’s traveling faster than 20 miles per hour and are more likely to avoid crossing, thus not getting hit. 

Director of New York City-based Transportation Alternatives Paul Steely-White asked on Twitter for a plain English translation of this three-year old journal article about vehicle speeds and something called “looming”.

The article is called “Reduced Sensitivity to Visual Looming Inflates the Risk Posed by Speeding Vehicles When Children Try to Cross the Road”.

Skip to the end if you want the plain English translation, but I’ve posted the abstract below followed by excerpts from Tom Vanderbilt’s Traffic.

ABSTRACT: Almost all locomotor animals respond to visual looming or to discrete changes in optical size. The need to detect and process looming remains critically important for humans in everyday life. Road traffic statistics confirm that children up to 15 years old are overrepresented in pedestrian casualties. We demonstrate that, for a given pedestrian crossing time, vehicles traveling faster loom less than slower vehicles, which creates a dangerous illusion in which faster vehicles may be perceived as not approaching. Our results from perceptual tests of looming thresholds show strong developmental trends in sensitivity, such that children may not be able to detect vehicles approaching at speeds in excess of 20 mph. This creates a risk of injudicious road crossing in urban settings when traffic speeds are higher than 20 mph. The risk is exacerbated because vehicles moving faster than this speed are more likely to result in pedestrian fatalities.

The full text is free to download, but I think Steely-White needs to learn more now, so I pulled out my favorite book about driving, Tom Vanderbilt’s “Traffic”.

Page 95-97:

For humans, however, distance, like speed, is something we often judge rather imperfectly. Unfortunately for us, driving is really all about distance and speed. Consider a common and hazards maneuver in driving: overtaking a car on a two-lane road another approaches in the oncoming lane. When objects like cars are within twenty or thirty feet, we’re good at estimating how far away they are, thanks to our binocular vision (and the brain’s ability to construct a single 3D image from the differing 2D views each eye provides). Beyond that distance, both eyes are seeing the same view in parallel, and so things get a bit hazy. The farther out we go, the worse it gets: For a car that is twenty feet away, we might be accurate to within a few feet, but when it is three hundred yards away [900 feet], we might be off by a hundred yards [300 feet]. Considering that it takes about 279 feet for a car traveling at 55 miles per hour to stop (assuming an ideal average reaction time of 1.5 seconds), you can appreciate the problem of overestimating how far away an approaching car is – especially when they’re approaching you at 55 miles per hour.

[Here comes the keyword used in the journal article, “looming”]

Since we cannot tell exactly how far away the approaching car might be we guess using spatial cues, like its position relative to a roadside building or the car in front of us. We can also use the size of the oncoming car itself as a guide. We know it is approaching because its size is expanding or looming on our retina.

But there are problems with this. The first is that viewing objects straight on, as with the approaching car, does not provide us with a lot of information.

[…]

If all this is not enough to worry about there’s also the problem of the oncoming cars speed. A car in the distance approaching 20 miles per hour makes passing easy, but what if it is doing 80 miles per hour? The problem is this: We cannot really tell the difference. Until, that is, the car gets much closer — by which time it might be too late to act on the information.

[the topic continues]

Plain English translation

However, nothing I found in Traffic relates children and “looming”. The bottom line is that children are worse than adults at detecting the speed of a car coming in the cross direction and thus decide wrongly on when to cross the street.

Update: Based on Vanderbilt’s writing, it seems that humans cannot really be taught how to compensate for looming, to build a better perceptual model in the brain to detect the difference between cars traveling 20 and 80 MPH. If this is true, and I’d like to see research of pedestrian marketing and education programs designed for children, it may be that we should stop trying this approach.

Just bought some new books (bikes and urban planning stuff)

Two books: Buckminster Fuller’s Critical Path (haven’t finished) and Tom Vanderbilt’s Traffic (finished).

While I hurry and finish up this 900 page CIA spy novel (The Company by Robert Littell) that I bought for $1 in Richmond, VA, I bought a couple more books. I still have to finish Straphanger, too!

I ordered Genius of Common Sense: Jane Jacobs and the Story of The Death and Life of Great American Cities (book link) by Glenna Lang and Marjory Wunsch that I found on the blog Human Transit. I also ordered City Cycling by John Pucher and Ralph Buehler; this book won’t be available until October 19th. I applied for the Ph.D. program at the urban planning college at Rutgers University where both men teach. I was not accepted. Boo, hoo. But Pucher and Buehler are the foremost researchers on bicycling around the world (they mostly research bicycling in English-speaking countries and compare them to places in Europe).

Some more books that I want to read eventually:

1. Just Ride: A Radically Practical Guide to Riding Your Bike by Grant Peterson.

I flipped through this book at the Peggy Notebaert Nature Museum book store after viewing the Bikes! The Green Revolution exhibit on its last day. One of the features in the book was why you shouldn’t ride in a straight and predictable line in urban traffic (as the Chicago Bike Map and other resources articulate). Instead you should be controllably unpredictable, to demonstrate to drivers that you’re a little wobbly and they should give you more space. There’s also guidance on choosing and maintaining a bicycle. I’d like to know what Peterson has to say about that. This reminds me, I had a short discussion with a friend (who hasn’t biked in years) who’s reading Zen and the Art of Motorcycle Maintenance. There’s a lot in there that’s not instructions on fixing a motorbike that I’d like to peruse.

2. Pedaling Revolution: How Cyclists Are Changing American Cities by Jeff Mapes.

I probably won’t read this book; I feel it’s one of those books that will be full of everything I already know. Or it will be preaching to the choir. Or it will help me feel great about myself and my choices and inspire me to do something right this moment but I won’t because I’m busy with other stuff. And then I’ll tell everyone else to read it. But really, I just want others to read it and others to see how I (think) I am changing (one) American city (which involves me pedaling a bicycle and constantly living to tell about it). It’s really hard to change cities alone or with just a small group of people. We need more people who are willing to get involved. Bring your own ideas, act on your own ideas, or come borrow mine (or some of the ideas in the myriad sustainable transportation groups and communities I’m involved in).

When I’m not reading, I’m making the Chicago Bike Map app. Please buy it. Support a starving college student. Oh, wait, that was never really my style. But I do want an iPad…

What books are you reading?

I updated some formatting of this post. It’s ugly to have all these links to books with long titles. 

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