Tag: children

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.

CDOT’s response to helmet inquiry at MBAC

Waiting at a red light on Milwaukee Avenue at Western Avenue. 

Erica Salem of the Chicago Department of Public Health (CDPH) emailed me in February asking about data on children’s bike accidents (crashes) and any related data about ER visits and head injuries. I forwarded her to my friend Bill who is working on such data at UIC’s Urban Transportation Center (UTC).

She was looking for information to make the case for kids to use helmets while biking. And she brought this up at the June 2012 Mayor’s Bicycle Advisory Council (MBAC). She’s a member of the council under the new rules and format.

Here’s a paraphrased version of the discussion:

Erica Salem (ES): How do you quantify the increase in bike riders in the city?

Mike Amsden: That’s a huge challenge. Bike/ped data collection is very difficult. Right now it’s just work trips, and there’s even talk of eliminating that. We do before/after data collection of bikeway facilities. That’s where this Green Lane Project will come in and help with promotion and resources.

ES: The CDC released data showing 88% CPS middle schoolers and 94% of CPS high schoolers don’t wear a helmet when biking. Some of us think there should be an ordinance for helmet use in children. And some of us don’t.

Charlie Short: Safe Kids Program out of Children’s Memorial has done bike helmet giveaway. Targets low-income children. That seems to be where most initiative is coming from.

ES: The funds are drying up. I’ve talked to them already.

James Boratyn (of Illinois Department of Transportation): IDOT helps fund Children’s Memorial’s Safe Kids Program [also funds Bike Ambassadors]

Alex Wilson (of West Town Bikes): Major issue was storage concerning their move. We just filed a grant for 500 helmets.

Luann Hamilton (representing the Chicago Department of Transportation): We’ve always taken the position to provide education, outreach, and providing free helmets, as opposed to mandate. Of all the issues the police are dealing with, it doesn’t seem like a useful way to deal with the issue. [emphasis mine]

A cogent and welcomed response.

Mayor Bloomberg (of New York City) responds directly to a question about helmet laws:

It would be better if everybody wore a helmet. I think in a practical sense a lot of people won’t, and they’re better off taking a bike than driving or walking in the streets and getting pedestrian accidents (sic). The most important thing we can do is separate bicycles lanes from traffic, and that’s one of the things we’re really trying to do.

Infrastructure and traffic enforcement will do more to reduce injuries than helmets.

My friend Brian pointed me to this article about how a helmet law may make a killed child’s parents (somewhat) responsible for their own child’s death. A 14-year old boy was cycling and killed by a then-48-year old driver. The boy was not wearing a helmet but state law requires that children 15 and younger wear helmets while cycling. The lawsuit was filed by the driver, from prison, in 2010. I don’t know what the outcome is.

Updated June 19 at 13:34 to add Mayor Bloomberg’s response to a question about helmet laws. Updated June 28 at 20:31 to add link to child death article.