Tom Vanderbilt says "Children At Play" signs don't "change driver behavior nor to do anything to improve the safety of children in a traffic setting." Vanderbilt says the bigger problem is residential neighborhoods with speed limits of 35 or higher:
It's not simply that fatality risks begin to soar at impact speeds of more than 20 mph, but that, as a study by John Wann and colleagues at Royal Holloway University in London has suggested, children, until well into their teens, are unable to detect during a normal crossing of the street the approaching speed and distance of cars above a threshold—also 20 mph.
The Dish 