Seoul is installing 300 new street signs to warn pedestrians about the dangers of walking while engrossed in their smartphones - but not everyone's convinced they'll be noticed.

The first signs have been installed at five locations in the hope that they'll stop "smartphone zombies" in their tracks, the Korea Times reports . One sign at a major traffic intersection shows a person staring at a handheld device, oblivious to their imminent collision with a car.

While some signs are attached to traffic light poles, others have been plastered onto pavements in order to attract the lowered gaze of those distracted by their gadgets. But some locals aren't sure that signage is the solution. One man points out that "most people who are peering at their phones on the street aren't going to be able to see them".