30 mph traffic is too fast for children to judge accurately, study finds


Philip Langdon

New Urban Network


Adult pedestrians can accurately judge the speeds of vehicles traveling toward them at up to 50 mph, say researchers at Royal Holloway College, University of London, England. But for elementary school children, it’s a different matter. Children simply don’t have the perceptual ability to make an accurate judgment.

“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,”said John Wann, a professor in the university’s Department of Psychology.

Wann led researchers who measured the perceptual acuity of more than 100 elementary school pupils, the university said in a news release describing the study’s results. The judgments of children of primary school age “become unreliable once the approach speed goes above 20mph, if the car is five seconds away,” the university said.

“These findings provide strong evidence that children may make risky crossing judgements when vehicles are travelling at 30 or 40 mph,” Wann concluded. He emphasized that “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.”

Since completing the study, the researchers have begun looking at the potential for using virtual reality systems to make children more aware of their potential errors, the university noted. But the simplest solution, according Wann, lies in traffic regulation.

The study, published in the international journal Psychological Science, is part of a larger project sponsored by the Economic and Social Research Council aimed at understanding the perceptual factors than can lead to pedestrian accidents

The Environmental Transport Association (ETA), a British organization that raises awareness of transportation’s impact on people and the environment, said, “The fact that children find it difficult to judge the approach speed of vehicles traveling at over 25mph is yet another argument for 20mph limits in the streets where people live, work and play.” The City of London is currently considering whether to impose a 20 mph speed limit in much of its center.

Technology to the rescue?

In many places, enforcement of a 20 mph speed limit would be difficult. Consequently, ETA Director Andrew Davis argues for installing technology that automatically reduces a vehicle’s speed in certain conditions.

“Networks of average speed cameras would do the job, but lamp posts bristling with more cameras are hardly desirable,” Davis wrote in an commentary in March. He noted that more than ten years ago the ETA and likeminded organizations founded the Slower Speeds Initiative, one of whose aims was “to ensure that all road vehicles had variable speed limiters.”

Davis wrote:

Certain classes of road vehicles, like heavy goods vehicles and public services vehicles, have maximum speed limiters but we want limiters extended to all vehicles.

… we want the limiter to reflect not just the national maximum speed – currently 70mph – but the maximum speed in any locality. Therefore the speed limiter will ensure the driver could not drive faster than 30mph where that maximum speed applies.

A while ago I drove such a vehicle. The accuracy was stunning. I entered London via the M1 at 70mph and once the 50mph limit came into force the car slowed to 50mph. On moving onto local roads the speed reduced to 30mph. If you imagine a dual-carriageway with a parallel access road a couple of metres away I was able to travel along the dual-carriageway at 50mph but as soon as I moved to the access road I was reduced to 30mph.

The ETA has long held that all vehicles should have variable speed limiters fitted as standard by law. As with cruise control, the driver could press through the limiter to pass above the speed limit; allowing such a level of driver control would help its earlier acceptance. Every time the vehicle returned to below the speed limit the limiter would become active again.

A decline in walking

The United Kingdom has seen the number of children walking to school drop over the years, just as it has in the US. In a 2008 news release, ETA said, “The proportion of 7-10 year olds making their way to school independently fell from 19 per cent in 2003 to 15 per cent last year. Only 13 per cent of children are now allowed to cross the road on their own.” ETA blames dangerous vehicular traffic for some of the decline in the number of children walking to school.

Said an ETA spokesperson: “The fact that fewer and fewer children are allowed to cross the road or travel to school unaccompanied is a disturbing trend – everything else being equal children who get some exercise on their way to school are healthier and perform better academically than those driven to school.”