Not what happened in that experiment, it’s in the article: “Over the initial three-day trial, almost 25,000 cars were caught on camera, according to the YouTub

Not what happened in that experiment, it’s in the article: “Over the initial three-day trial, almost 25,000 cars were caught on camera, according to the YouTube video. The average speed of cars travelling through the school zone was reduced from 32km/h before the trial to 25km/h during the experiment.” Enforcement of fines plus the possibility of losing one’s license i think would be enough to ensure the effectiveness, but maybe also displaying each driver’s speed visibly is a factor? In fact I imagine for the daycare experiment if they had combined fines + the possibility of having ones child dismissed from the program it also would have been more effective.