Because – according to ER doctors – distracted walking leads to more injuries per mile than distracted driving. In fact, as many as 10% of ER visits are caused by accidents involving cellphones. The main problem is that people staring at a screen aren’t paying attention to what’s in front of them. So, they walk into walls, fall down stairs, and step out into traffic. That’s why city engineers in London have cushioned the light poles in high-pedestrian areas – and it’s dramatically reduced the number of walking injuries.