Whether or not the trial expands will depend on the effectiveness of the signs, and there's no certainty that they'll work. The whole problem is that people are buried in their screens -- will they look up for long enough to notice, let alone care? It's hard to imagine Seoul officials giving up on the idea quickly, though. While smartphones are popular in many places, South Korea is particularly obsessed given that both LG and Samsung call the country home. Even a cursory reminder to pay attention may have a tangible effect.