TOKYO - When the lights change at the Shibuya crossing in Japan's capital, one of the world's busiest pedestrian thoroughfares, hundreds of people with their eyes glued to smartphones pick their way over the road.
Despite being engrossed in the latest instalment of Candy Crush or busy chatting with their friends on messaging app Line, most manage to weave around cyclists, skateboarders and fellow Tokyoites.
But the growing ranks of these cellphone addicts are turning cities like Tokyo, London, New York and Hong Kong into increasingly hazardous hotspots, where zombified shoppers appear to be part of vast games of human pinball.
"Hey, watch it!" barks a middle-aged salaryman as a hipster typing on his smartphone slams into him during one recent Friday evening crush hour.
"Incidents involving people walking or on bicycles account for 41 per cent of phone-related accidents," Tetsuya Yamamoto, a senior official at Tokyo Fire Department's disaster prevention and safety section, told AFP.
"If people continue walking around looking at their phones, I think we could see more accidents happening." It goes beyond being an innocuous inconvenience where both people apologise before continuing on their merry way.
Tokyo Fire Department, which runs the ambulance service in the megalopolis, says that in the four years to 2013, 122 people had to be rushed to hospital after accidents caused by pedestrians using cellphones.
As well as the vaguely comedic incidents of businessmen smacking into lamp-posts or tripping over dogs, this total also included a middle-aged man who died after straying onto a railway crossing while looking at his phone.
More than half of Japanese now own a smartphone and the proportion is rising fast, including children who customarily walk to and from school.
Research by Japanese mobile giant NTT Docomo estimates a pedestrian's average field of vision while staring down at a smartphone is just five per cent of what our eyes take in normally.
"Children wouldn't be safe in that situation," said Hiroshi Suzuki, manager of corporate social responsibility at the company. "It's dangerous and it's our job to make sure it doesn't actually happen." The company ran a computer simulation of what could occur in Shibuya if everyone crossing the intersection was looking at their smartphones.
The results, based on a fairly average 1,500 people swarming over the road at any one time, were alarming: 446 collisions, 103 knockdowns and 21 dropped phones. Only around a third get to the other side without incident.