Call for more 20mph zones as research shows children "can't see" faster vehicles

Study shows children differ from adults in ability to accurately judge vehicle speed

by Simon_MacMichael   November 23, 2010  

20 sign.jpg

New research has found that children are unable to accurately see or judge the speed of vehicles traveling at more than 20mph, prompting calls from campaigners to introduce more 20mph zones in residential areas to protect youngsters from the dangers posed by traffic.

The study, which is due to be published in the journal Psychological Science, was conducted by vision scientists at Royal Holloway, University of London, and assessed the ability of children to see cars approaching them as they crossed the road.

It found that where vehicles were traveling at speeds above 20mph, children of primary school age, 6-11 years, might not be able to determine that a car was approaching them.

According to the 20’s Plenty for US campaign, the finding “strongly supports arguments for implementing and enforcing 20 mph speed restrictions in areas with child pedestrians such as residential streets.”

In the study, it was found that a “speed illusion” could cause pedestrians, whatever their age, as well as drivers at junctions, to underestimate the speed of vehicles that are traveling more quickly and in some instances not see them at all.

The researchers undertook a survey of the perceptual acuity of more than 100 primay school children to identify the level of speed of approach that they were able to detect. Unlike adults, who could accurately judge speeds of up to 50mph, it was found that children’s estimates became unreliable once 20mph was exceeded.

Professor John Wann, who headed the research team, commented: “This is not a matter of children not paying attention, but a problem related to low-level visual detection mechanisms, so even when children are paying very close attention they may fail to detect a fast approaching vehicle.”

Professor Wann maintained that the most straightforward solution to the problem was one of traffic regulation, saying: “These findings provide strong evidence that children may make risky crossing judgements when vehicles are travelling at 30 or 40 mph.

"In addition, the vehicles that they are more likely to step in front of are the faster vehicles that are more likely to result in a fatality. Travelling 1 mile though a residential area at 20 mph vs. 30 mph will only add 60 seconds to journey time. We encourage drivers to take a minute and save a child’s life”.

Anna Semlyen, Campaign Manager for 20’s Plenty for Us insisted: “We cannot address child road safety by simply teaching them to pay more attention. Child pedestrians can’t judge approach speeds as well as adults.

“It’s simplistic to blame children and suggest they “run out”, without checking. But this study suggests it’s drivers going too fast that create errors, as it is then impossible for children to make correct judgments. It’s up to adult society to protect families through 20 mph limits where people live and for drivers to obey the signs.“

The study was carried out as part of a wider project backed by UK research council ESRC to discover perceptual factors that can potentially cause pedestrian accidents. Recently, findings were published in the Proceedings of the Royal Society that used brain imaging research that determined that a key factor in assessing and anticipating collisions occurred at brain-stem level, acting in effect as “a low-level early detection system.”

7 user comments

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i'm all for 20mph across the board, but where i live its been 20mph since feb/march this year and still most people seem to be driving faster than 20mph. and no one seems to be policing or enforcing it.

much like mobile phone use whilst driving and jumping amber/red lights behavior, it just seems to be getting worse. or maybe im noticing it more?

Fringe's picture

posted by Fringe [1097 posts]
23rd November 2010 - 16:51

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I teach kids to ride bikes and have to say I would be all for this too 20mph in residential areas. Not an area of research I've considered before, but on reading this I will now be looking for any anecdotal evidence in line with the above findings.

There are definitely a growing number(in my experience) of drivers who won't even bare being held up for 5 seconds for the sake of anyone, no mater how vulnerable the other road user is.

Is this a symptom of the 24/7 society we have created? Thinking

for me - The ride is about adventure, camaraderie and the sense of accomplishment that comes after a long day in the saddle.

Mountain-Nic's picture

posted by Mountain-Nic [119 posts]
23rd November 2010 - 21:20


Meanwhile in Scotland a report just released highlights that 1 in 10 children have been injured last year in motor accidents. The research also highlighted that the children said that the cars were travelling too fast!!!

This surely should reinforce the cause for mandatory 20mph speed limits in all of our urban areas which no doubt raise the hackles of the motoring bodies and the drivers!

While young people need to be taught how to cross the road - bring back the Tufty Club I say!! The tuition of drivers - car, HGV, PSV, PCV needs to be radically overhauled to include the necessary skills of dealing with vunerable road users and hopefully make our roads safer.

giff77's picture

posted by giff77 [1185 posts]
23rd November 2010 - 21:54


It feels hellishly slow in a car but I'm all for a 20mph speed limit for most residential areas. Bring it on. There'll be lots of motorists bleating about 'speeding cyclists' travelling at over 20 mph though!

Silly me. You're probably right....

MercuryOne's picture

posted by MercuryOne [1218 posts]
23rd November 2010 - 23:56


As Fringe says though, not much point in having 20mph zones if they're not enforced and from what i've read lots of police forces aren't interested in enforcement - even less so after the Tories pretty much veto'd installing speed cameras on residential streets. Maybe what needs to happen is streets need to be reclaimed by their residents and the environment changed so that it forces drivers to slow down - not neccessarily with speed bumps and not necessarily at great expense, but in ways that get the message across that motorists have to share the roads with other people – Sustrans have done a lot of work on things like this and I saw something about a group of residents doing something along the same lines in, of all places, the Daily Mail

Tony Farrelly's picture

posted by Tony Farrelly [4201 posts]
24th November 2010 - 0:30


Worth also noting in addition that drivers field of perception narrows down as speed increases above 20mph at 50mph you become more focussed on the road in front and traffic in the distance. All down to evolution as we evolved to operate at running speeds (20mph is about the fastest a human can manage) and the ability to observe and crash into things at up to 20mph is surviveable for a normal standard issue body.

The kids ability to judge speeds and distances is also a well made point. Very few kids can co-ordinate to catch or hit a ball thrown across the street, on a consistent basis, until they get the hand/eye coordination bit sorted. No surprise then that they have difficulty judging traffic speeds and distances. For some adults the ability is more developed - compare the practised jay-walker with the rabbit in the headlights who freeze in horror and then step backwards into your path. Watch the couriers 'flow' through traffic, compared to the slow and steady riders.

47 years of breaking bikes and still they offer me a 10 year frame warranty!

A V Lowe's picture

posted by A V Lowe [560 posts]
24th November 2010 - 10:05


Most days I commute to work through a 20mph zone that passes two schools

It's on a downhill so I am doing 20mph+ on the bike. And every day cars overtake me. I have seen a group of hi viz wearing vigilantes using a hand held speed camera to enforce the 30 mph further up the same road but there is no enforcement in the 20mph zone

It is usually cars that overtake and not commercial vehicles or buses.

vorsprung's picture

posted by vorsprung [298 posts]
24th November 2010 - 11:38