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.
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.
Read the whole article here: http://newurbannetwork.com/article/30-mph-traffic-too-fast-children-judge-accurately-study-finds-14515