Did that mechanical voice just say it’s safe to cross the street? It’s a dilemma every blind person faces when they are about to step off the curb. What if the camera on the back of your mobile phone could assess the signals and your path to make a crossing safer? A small team of AI engineers at the startup AYES took on that challenge and created the OKO app, which uses computer-vision-based AI to “read” the signals and suggest when it’s safe to cross. How does the app work and just how safe is it?